Alien World Final

What wavelength light does the Spitzer Space Telescope measure? A) x-ray B) gamma-ray C) alpha radiation D) beta radiation E) infrared light

E) infrared light

The burner on your stove reaches a temperature about 500K. Wein's law states that the wavelength of the peak of the black body emission is λ=0.3cm(1K/T). Using Wein's law, what wavelength light does this correspond to, expressed in cm?

0.0006cm 0.3cm * ( 1k/500K) = (0.3/500) cm = 6x10-4cm

If the planet emitted no measureable amount of light, as seen by an observer at Earth, how big would the secondary eclipse signal be? (Here secondary eclipse signal is the fractional drop in light from the system when the planet passes behind the star) A) 0 B) 1 C) infinity

A) 0 If the planet's light was so small as to not be detectable, then you would not observe a drop in light when the planet passes behind the star.

When all the sunlight is reflected back out into space, how much thermal emission is there from a planet? A) 0 Watt B) 1 Watt C) infinity Watts

A) 0 Watt If all the starlight is reflected back out into space, there is no energy absorbed (energy in), and there will be no thermal energy emitted (energy out=energy in).

Why did the discovery of 51 Peg b by the radial velocity method disagree with expectations from the nebular and condensation theories? A) 51 Peg b is very close to the star, and it was expected that gas giants must orbit outside the snow line according to condensation theory B) 51 Peg b's orbit is very eccentric, with e> 0.5, which disagrees with the idea that the planet orbits must be circular since the gas orbits are circular in nebular theory C) 51 Peg b's orbit is known to be perpendicular to the rotation of the star, which disagrees with nebular theory that says the orbits must align with the spin

A) 51 Peg b is very close to the star, and it was expected that gas giants must orbit outside the snow line according to condensation theory

Which lack of data (A or B) is probably real and which is probably due to those planets being hard to find with the RV method (due to small star velocity)? ( refer i A) A is a real (those objects don't exist in nature), B is because they give small signals B) B is a real (those objects don't exist in nature), A is because they give small signals

A) A is a real (those objects don't exist in nature), B is because they give small signals

As compared to a H/He gas giant planet with no solid core, a H/He gas giant planet with a large solid core, made of heavy elements, has A) A smaller radius B) A larger radius C) Exactly the same radius

A) A smaller radius The heavy element core takes up less space at the center than H/He gas would, and so the radius is smaller with the heavy element core. Basically this is because the scale height is smaller for a gas made of heavier particles.

If white light passed through a glass tube containing (cool) sodium gas, what kind of spectrum would result? A) Absorption spectrum B) Emission spectrum C) Thermal (continuous) spectrum

A) Absorption spectrum A continuous spectrum goes into the tube, and the atoms in the tube absorb at certain wavelengths, giving an absorption spectrum.

When measuring their radii during transit, why do exoplanets appear larger when observed at wavelengths near the center of the sodium D line? A) At those wavelengths, the light interacts with sodium atoms much more strongly, and the gas is more opaque to higher up in the atmosphere, making it seem like the radius is larger. B) When the observer looks at the planet in these wavelengths of light, the planet knows we are looking at it, and grows in size to make itself more easily visible C) aliens

A) At those wavelengths, the light interacts with sodium atoms much more strongly, and the gas is more opaque to higher up in the atmosphere, making it seem like the radius is larger.

The atmospheric scale height, H, is H=kT/(Mg), where T=temperature and M=mass of the particles in the gas. Let k and g be constants here.Is the scale height bigger for high temperature small particle mass, or low temperature large particle mass? A) Bigger H for large T, small M B) Bigger H for small T, large M

A) Bigger H for large T, small M T is in the numerator, so larger H for larger T M is in the denominator, so larger H for smaller M.

How is the transit method used to meaure the radius of the planet? A) By measuring the fractional drop in light from the star, having an independent means of knowing the stellar radius, and using the fact that the drop in flux is the ratio of planet area to star area. B) By directly measuring the radius of the star using a telescope image and using the knowledge that planet radii are 1/10 of the star's radius. C) By measuring the radial velocity of the planet. D) By measuring the radial velocity of the star.

A) By measuring the fractional drop in light from the star, having an independent means of knowing the stellar radius, and using the fact that the drop in flux is the ratio of planet area to star area. The drop in light is due to the planet blocking the star. If you measure the drop and know already the radius of the star (from it's measured spectrum and models of stars) you can derive the planet's radius.

With seismic waves, what is measured and what is inferred from the data? A) Distance and time measured, wave velocity inferred B) Time and velocity measured, distance inferred C) Velocity and distance measured, time inferred

A) Distance and time measured, wave velocity inferred From having many seismic measuring stations, each recording the arrival times of the waves, the position of the Earthquake can be determined, giving the distance. Given distance and time, divide to get velocity

Question about figure 3 in the article by Batalha. The most abundant planet (highest occurence rate, or number of planets per star) is A) Earth radius B) Jupiter radius

A) Earth Radius In the left plot, it shows that the occurence rate of 1 Earth radius planets is 0.1, while the occurence rate of 10 Earth radius (=1 jupiter radius) planets is roughly 30x smaller.

Just based on transit probability, is it more likely to find an Earth-size planet close to the star or a Jupiter-size planet far from the star? A) Earth close B) Jupiter far

A) Earth close In both cases the planet is much smaller than the star, and planet radius doesn't matter. Close has higher transit probability than far.

What planet is NASA's Juno satellite orbiting? A) Jupiter B) Saturn C) Mars D) Mercury E) Vulcan

A) Jupiter

What might have been a reason that initial radial velocity detections before 1995 were thought to be stars rather than planets? A) Only the minimum mass is measured, and if sin(i) is small, the true mass can be much larger, even up to the mass of a star B) Because some objects of 1 Jupiter mass can be stars and some can be planets C) Because it was well known that the only planets that can possibly exist in the universe are the ones in our own solar system

A) Only the minimum mass is measured, and if sin(i) is small, the true mass can be much larger, even up to the mass of a star

The first shaking you feel from an Earthquake is due to which wave? A) P-wave B) S-wave C) Raleigh wave D) Love wave

A) P-wave P (primary) waves travel the fastest, and get there first

Why might it make sense to call Pluto a big comet? A) Pluto orbits in the Kuiper belt, a reservoir of comets, and has a similar composition to other Kuiper belt objects B) Pluto orbits in the Oort cloud, a reservoir of comets

A) Pluto orbits in the Kuiper belt, a reservoir of comets, and has a similar composition to the Kuiper belt objects

the Marcy et al paper. What is more common, Jupiter-size planets (~10 Earth radii), or Super-Earth size planets (1-2 Earth radii)? A) Super-Earth's with R=1-2 REarth B) Jupiter-size planets with R=10REarth

A) Super-Earth's with R=1-2 REarth The small radius objects have occurence rate 10-20%, which the large radius objects have radius

In hot Jupiters, the H2O that is detected during transit is in what form? A) Vapor B) Solid ice crystals C) Liquid droplets D) Luxurious swimming pools of the squid creatures E) Ice 9

A) Vapor At the 1000's of Kelvin hot temperatures in planets near the star, water is in vapor phase, not liquid or solid.

A 1 Jupiter mass planet is found with a radius of R = 2 Jupiter radii. It's known that this planet circles a star which is younger than 1 million years old. Does this planet's radius agree with the simple cooling models? A) Yes B) No

A) Yes Very young planets are expected to have radii in the 1.5-2 Jupiter radii range. These planets are born hot, with a large radius, and then they cool and shrink over time

In the past, the moon was A) closer to Earth, and the "month" was shorter B) further from Earth, and the "month" was longer

A) closer to Earth, and the "month" was shorter

Is matter continuous, so that you can keep subdividing it and never find a smallest unit, or is it discrete, in that if you keep subdividing it you will eventually find a smallest piece? A) discrete B) continuous

A) discrete We call these smallest pieces "atoms"

Why do electrons exert a pressure (picture particles hitting a surface) even at zero temperature (where the random thermal motions are zero by definition). A) electrons are fermions. since no two fermions can be in the same quantum state, they must be moving even at zero temperature B) electrons are bosons. because no two bosons can be in the same quantum state they must move even at zero temperature C) this is a trick question. electrons are fermions. because fermions tend to all pile up in the same quantum state, they don't move at zero temperature.

A) electrons are fermions. since no two fermions can be in the same quantum state, they must be moving even at zero temperature

An emission spectrum is produced by A) emission of line photons by a tenuous cloud of gas B) removal of line photons from a continuous spectrum as it passes through a a tenuous cloud of gas

A) emission of line photons by a tenuous cloud of gas

The shortest wavelengh, highest energy photons are called A) gamma rays B) radio waves C) ultraviolet

A) gamma rays

For most of human history it was believed that Earth was at the center of the Universe. This idea is referred to as A) geocentric B) heliocentric C) egocentric D) eccentric

A) geocentric

Blue light has higher frequency than red light. Thus, blue light has: A) higher energy and shorter wavelength than red light. B) higher energy and longer wavelength than red light. C) lower energy and shorter wavelength than red light.

A) higher energy and shorter wavelength than red light.

The light-bending angle A) increases with lens mass and decreases with closest approach distance B) decreases with lens mass and decreases with closest approach distance C) decreases with lens mass and increases with closest approach distance D) increases with lens mass and increases with closest approach distance

A) increases with lens mass and decreases with closest approach distance alpha = GM/(bc2), M is in the numerator, b is in the denominator

Which size telescope dish will both collect more light, making it easier to detect faint objects, as well as have better angular resolution, which makes sharper images? A) larger telescope dish B) smaller telescope dish

A) larger telescope dish

From Figure 4 in the Marcy et al paper, and the discussion in the text, what range of planetary radii seem to correspond to "rocky" planets with densitiy higher than Earth (5.5g/cm3)? A) less than 1.5 Earth radii B) 1.5-4 Earth radii C) 4-10 Earth radii D) greater than 10 Earth radii

A) less than 1.5 Earth radii

Which of the following extrasolar planets would be the most difficult to detect using the Doppler shift method? A) low mass planet far from its parent star B) a massive planet close to its parent star C) a low mass planet close to its parent star D) a massive planet far from its parent star

A) low mass planet far from its parent star

Habitable planets around which type of star are most heavily affected by flares? A) low mass stars B) high mass stars

A) low mass stars To be habitable, the planet must move close to the low mass star since it produces so little light/heat. But because it is so close the flares have a bigger effect on the atmosphere. Also, low mass stars tend to have more flares than stars like the sun.

What is the energy source for solar/stellar flares? A) magnetic fields B) nuclear fusion C) nuclear fission D) the e​nergizer bunny

A) magnetic fields Motions inside the sun pump energy into the magnetic fields outside the sun. This energy is suddenly released in "magnetic reconnection" events

For a light ray which passes by the sun near the surface, the bending angle is A) much less than 1 radian B) 1 radian C) much greater than 1 radian

A) much less than 1 radian except for neutron stars and black holes, the bending angle is always very very small

Which of these is NOT the role of an accretion disk? A) nuclear fusion reactions create heavy elements from hydrogen B) angular momentum has to be removed from the gas by friction in the accretion disk for the gas to be able to move in to the star C) magnetic fields have to be removed from the gas, otherwise magnetic forces would overpower gravity D) planets form in the disk

A) nuclear fusion reactions create heavy elements from hydrogen

How many times does our Moon rotate per month? A) once B) twice C) three times

A) once This is why we always see the same side of the moon

In regards to radiation, the opposite of transparent is A) opaque B) dense C) rarefied

A) opaque transparent means light is allowed to go through a medium. opaque means light is absorbed, and cannot go through a medium.

assume planets form around all different types of stars with the same frequency, and at all different orbital radii around the star. most of the planets in the galaxy which are in their habitable zone should be A) orbiting inside the Earth-Sun distance B) orbiting outside the Earth-Sun distance

A) orbiting inside the Earth-Sun distance

According to the nebular theory for the formation of the solar system A) planets should be rotating in the same direction as they orbit the Sun B) planets can be rotating in any random direction compared to the direction they orbit the Sun C) planets should be rotating in the opposite direction to the direction they orbit the Sun D) no prediction is made as to the directions fo rotations of the planets

A) planets should be rotating in the same direction as they orbit the Sun

You see the solar system planets in the night sky in A) reflected visible light B) thermal infrared emission

A) reflected visible light Our eyes cannot see infrared light, the thermal emission. We see reflected visible (optical) light from the sun.

What aspect of the collapsing nebula does conservation of angular momentum explain? As the gas cloud collapses, it.... A) rotates faster B) rotates faster AND heats up C) heats up D) cools down E) keeps the same amount of mass

A) rotates faster

Stellar parallax is the apparent A) shift in position of nearby stars as the Earth moves around the Sun B) westward motion of a planet with respect to the background stars C) shift in position of nearby stars as the Sun moves about the center of the galaxy D) shift in position of nearby stars as the Earth rotates on its axis

A) shift in position of nearby stars as the Earth moves around the Sun

In our solar system, terrestrial planets are A) small, made mostly of rock and iron with high densities, and found close to the Sun B) large, made mostly of gases and liquids and low densities, and found far from the Sun C) small, made of pure rock with high densities, and found close to the Sun D) large, made of pure gases with low densities, and found far from the Sun

A) small, made mostly of rock and iron with high densities, and found close to the Sun

The first objects to form in the condensation theory of planet formation are A) small, since dust particles hit and stick together to form larger objects B) large, since large planets were made in big bang, and they have been getting gradually smaller due to collisions ever since

A) small, since dust particles hit and stick together to form larger objects

A quake occurs in an extrasolar planet, generating seismic waves. A measuring station on the exact other side of the planet measures both P (primary) and S (secondary) waves. The center of this planet must be entirely A) solid B) liquid

A) solid For earth there is a shadow zone for S-waves since our planet has a liquid outer core. In order not to have this shadow zone you need an entirely solid planet.

Your spaceship's dilithium crystals (power source for warp drive) have run out of power and you need to land your ship and find new ones. You ship should try to land on A) terrestrial planet B) Jovian planet

A) terrestrial planet

If you heat a rock until it glows, its spectrum will be: A) thermal radiation spectrum. B) an absorption line spectrum. C) an emission line spectrum.

A) thermal radiation spectrum. Objects heated to a high temperature emit thermal radiation spectrum

When the planet blocks the star it's called a A) transit B) secondary eclipse C) waning gibbous phase

A) transit

Transit timing variations (TTV's) are A) variations in the time interval between transits B) variations of the duration of successive transits

A) variations in the time interval between transits TTV's are variations in the time it takes the planet going around the star, since the other planets can pull it forwrad or back or the orbit.

Is water expected to be observed in the atmospheres of extrasolar planets? A) yes, for solar composition and the temperatures and pressures of interest, water is among the most abundant molecules. Water is also very opaque to starlight at certain wavelengths, making it detectable during transit. B) no, the atmospheres of extrasolar planets are far too hot for water to be stable C) no, almost all stars have a high carbon to oxygen ratio, and so we expect all oxygen is in CO rather than H2O D) no, water is always very transparent to all wavelengths of light, making it hard to detect even when it is there

A) yes, for solar composition and the temperatures and pressures of interest, water is among the most abundant molecules. Water is also very opaque to starlight at certain wavelengths, making it detectable during transit.

Roughly, what are the angular size of the Sun and moon A) 1 radian B) 1 degree of arc C) 1 arcminute D) 1 arcsecond

B) 1 degree of arc Note sun and moon have same angular size => eclipse of sun by moon! Answer is about ½ a degree, comparable to size of your thumb

Jupiter-mass planets are born hot and then cool off and shrink over time. They should shrink down to roughly Jupiter's radius over what time period? A) 1 year B) 1 million years C) 1 billion years D) 1 trillion years

B) 1 million years this time is short compared to the age of the star, which is more like 1 billion years.

What is the largest transit depth possible for any known object in our solar system passing in front of the Sun? A) 0.01% B) 1% C) 100%

B) 1% The largest object we know of orbiting outside the Sun is Jupiter, which has a 1% transit depth. Recall the transit depth is dF/F = (Rplanet/Rstar)2. Since Jupiter's radius is 10x smaller than the sun's, it has a transit depth of 1%. The Earth would give a transit depth of 0.01%, since it's radius is 100x smaller than the sun. We don't know of any object orbiting in our solar system that could block off the whole sun.

From Figure 4 in the Marcy et al paper, and the discussion in the text, what range of planetary radii seem to correspond to Uranus-Neptune-type planets, with low density, and hence large "envelopes" of low density (H/He) gas? A) less than 1.5 Earth radii B) 1.5-4.0 Earth radii

B) 1.5-4.0 Earth radii

If the p-wave speed is v=6km/sec, and the wave travels straight through the center of the Earth, what is the travel time? Use •R = 6000km •Total distance traveled is 2R=12,000km •Time = distance/speed A) 1000 sec B) 2000 sec C) 3000 sec

B) 2000 sec 2R=diameter = 12,000km 12,000km / (6km/sec) = 2,000 sec which is about 1/2 hour

Question about the article by Batalha. The big question. What is the occurence rate (number of planets per star) for sun-like "G-dwarfs" with Earth-size planets orbiting around them in the habitable zone? A) 2.2% B) 22% C) 222%

B) 22%

An isotope of the element Manganese (Mn) has an atomic number of 25 and a mass number of 55. Assuming the atom is neutral, this means it has A) 55 protons, 55 electrons, and 25 neutrons B) 25 protons, 25 electrons, and 30 neutrons C) 25 protons, 30 electrons, and 25 neutrons D) 25 protons, 25 electrons, and 55 neutrons

B) 25 protons, 25 electrons, and 30 neutrons

What is the difference between asteroids and comets? A) Asteroids are made of hydrogen and helium gas, while comets are made of liquid water B) Asteroids are rocky, with little water, and orbit between Mars and Jupiter. Comets formed in the outer Solar System, and so are water rich. C) Asteroids have "tails", while comets do not

B) Asteroids are rocky, with little water, and orbit between Mars and Jupiter. Comets formed in the outer Solar System, and so are water rich. When far from the sun, comets don't have a tail. As they approach the sun, volatiles like H2O are heated and become gaseous. They flow off the comet creating the tail.

What kind of planets do we expect to find with direct imaging? A) Bright planets very close to the star B) Bright planets very far from the star C) Dim planets very close to the star D) Dim planets very far from the star

B) Bright planets very far from the star Contrast: the brighter the planet, as compared to the star, the easier it is to detect. Angular resolution: the further the planet is from the star the easier to detect.

If you want to find transiting planets, why do you need to monitor a large sample of stars? A) Planets are intrinsically rare, and a large sample of stars must be observed before you can find even one star with a planet B) Even though planets are common around stars, only a small fraction have their orbits edge-on as viewed from Earth, and so a large enough sample of stars must be observed to make up for the low probability that any star-planet orbit is edge-on.

B) Even though planets are common around stars, only a small fraction have their orbits edge-on as viewed from Earth, and so a large enough sample of stars must be observed to make up for the low probability that any star-planet orbit is edge-on. Transit probability Ptransit = Rstar /d, where Rstar is the stellar radius and d is the star-planet orbital separation. For d >> Rstar , only a small fraction of planets will be viewed edge-on.

The Sun is perfectly stationary as the planets move around in orbit. A) True B) False

B) False

The detection of extrasolar planets was a complete accident as no one believed they existed and no one believed they could ever be detected A) True B) False

B) False

Which type of planet is easiest to find with the transit method? A) Gas giant planets far from the star B) Gas giant planets close to the star C) Earth-like planets far from the star D) Earth-like planets close to the star

B) Gas giant planets close to the star Large radius planets have a larger transit depth (drop in stellar brightness). Close-in planets have a higher probability of transiting.

Which types of planetary systems are expected to interact more strongly A) Low-mass planets on widely separated orbits B) High-mass planets on closely-packed orbits

B) High-mass planets on closely-packed orbits

Red light scatters better from A) Small molecules with size much smaller than the red light's wavelength B) Large water droplets, with size much larger than the red light's wavelength

B) Large water droplets, with size much larger than the red light's wavelength

What pieces of evidence support the Big Bang theory? A) Dark matter, dark energy and the Higgs boson B) Microwave background, galaxies moving away from each other, creation fo the elements H and He C) Stars for from collapsing gas clouds

B) Microwave background, galaxies moving away from each other, creation fo the elements H and He

The large moons around Saturn have densities near 1g/cc. They are likely composed of A) Mostly iron B) Mostly water

B) Mostly water the transit depth is (Rplanet/Rstar)2. so for a fixed Rplanet, if you decrease Rstar you get a bigger transit depth.

Earth orbits the Sun in 1 year, and Mars orbits the Sun in 1.9 years. Are Mars and Earth in an exact 2:1 mean motion resonance? A) Yes B) No

B) No For mean motion resonances, the ratio of the orbital periods must be very close to the ratio of two integers, e.g. 2:1 or 3:2. 1.9/1.0=1.9 is not exactly the ratio of two integers. 10% is not good enough. It is to be very close.

Is it possible that in our solar system, a gas giant was born beyond the snow line at the same time as the Earth, and then migrated all the way into the Sun and was destroyed? A) Yes B) No

B) No The Earth would have been in the way, so it would have either (1)been trapped in resonance and pushed into the Sun, or (2)been ejected from the Solar system.

The"month" must be at least 5 times shorter than the "year" for the moon not to be ripped away from the planet. Is our Moon in immediate danger of being ripped away from the Earth by the Sun's tidal gravity? A) Yes B) No

B) No The month (orbital period of Moon around Earth) is currently 12 times shorter than the year (orbital period of Earth around Sun).

Two gas giant planets were discovered in the habitable zone around the star HD 34445. Is life likely to have arisen on these two planets? A) Yes B) No

B) No No solid surface on gas giant planets! Objects heavier than the gas around them would fall down and be crushed by the pressure of the atmosphere!

Can rock planets have existed before stars existed? A) Yes, because the building blocks of rocky planets were made in abundance in the big bang B) No, because the elements required to make rock were created in stars C) Yes, we already observe such rocky planets in extremely young and distant galaxies D) No, because stars were created at the earliest moments of the big bang, and hence planets had to come later E) Yes, because this is seen in the documentary move "Contact"

B) No because the elements required to make rock were created in stars

Humans live inwhat sort of environment? A) Zero pressure B) Non-zero (finite) pressure

B) Non-zero (finite) pressure Standing on the surface of the Earth humans feel pressure due to the atmosphere. We would have problems surviving in environments that are much lower or higher pressure.

A supernova explosion of this star ejects the outside layers to space leaving only a neutron star at the center. A small amount of the inner layers falls back and forms an accretion disk in which planets form. What might the planets be made of? A) Hydrogen and helium B) Silicon and iron

B) Silicon and iron

The star TRAPPIST-1 is roughly the same size as Earth. Previously I had said that Earth-size planets could not be detected around Sun-like stars from the ground using the transit method. The reason was that the Sun has 100x bigger radius than Earth, giving a transit depth dF/F=10-4, and the "noise" due to the atmosphere (10-3) is far larger than this signal.But the Earth-size planets around TRAPPIST-1 were detected from the ground by the transit method. How is that possible? A) The country of Chile was launched into space B) TRAPPIST-1 is a smaller radius star than the Sun, making the transit depth larger C) TRAPPIST-1 is a smaller radius star than the Sun, making the transit depth smaller

B) TRAPPIST-1 is a smaller radius star than the Sun, making the transit depth larger The transit depth is how much of the light is blocked by the planet, and so is given by the ratio of the area of the planet to the area of the star. For fixed area of planet (Earth-size), if you make the star smaller, the planet will block a larger fraction of the star.

The key physical effect needed for tides to cause the moon to move away from the Earth is A) the GM/r2 component of the gravity that keeps the Earth and moon in orbit B) friction in t​he the tidally-forced water moving around in the Earth's oceans C) the GMR/r3 component of the tidal gravity that causes the up and down sloshing of the Earth's oceans

B) friction in t​he the tidally-forced water moving around in the Earth's oceans

Consider two planets with identical solid cores and the same surface pressure and temperature in the atmosphere. The only difference between the two atmospheres is composition. Their atmospheres are made of pure H2 molecules and pure CO2, respectively. Which atmosphere has density and pressure decreasing upward more rapidly? A) The H2 atmosphere B) The CO2 atmosphere

B) The CO2 atmosphere The pressure drops by a factor of e=2.71 for each scale height you move up. The scale height depends on temperature, gravity and the composition through the mass of the particle. Here the temperature and gravity are the same, but CO2 is much heavier than H2. So the scale height is smaller for the CO2 atmosphere and pressure and density decrease upward more rapidly.

From the Marcy et al article, a physical reason is given to understand the increase of density with radius for planets with R < 1.5 Earth radii. What is this physical reason? A) They are made of different elements, i.e. the composition is different B) The are made of roughly the same materials, but as the planet's mass and radius get bigger, the material becomes more compressed, increasing its density.

B) The are made of roughly the same materials, but as the planet's mass and radius get bigger, the material becomes more compressed, increasing its density.

"Starspots" appear as dark spots on the surface of stars, as they are cooler than the surrounding surface. Imagine a planet in the midst of transiting in front of its parent star. When the planet goes from blocking "normal" stellar surface to blocking a sunspot, how does the lightcurve change? A) The amount of light (the lightcurve) goes down, since starspots are cool B) The lightcurve goes up (more light), since now the planet is blocking a cool spot, which does not contribute much, rather than the rest of the stellar disk, which is hot and bright.

B) The lightcurve goes up (more light), since now the planet is blocking a cool spot, which does not contribute much, rather than the rest of the stellar disk, which is hot and bright. Imagine there are two flashlights, one bright and one dim. If you block the bright flashlight, you lose most of the light. If you block the dim flashlight, you only lose a little light

What is the difference between the S-wave and P-wave shadow zones? A) The p-wave shadow zone is due to refraction, while the s-wave shadow zone is due to the s-wave being a surface wave, unable to travel into the body of the Earth B) The p-wave shadow zone is due to refraction, while the s-wave shadow zone is due to both refraction and the inability to travel through liquid layers in the Earth

B) The p-wave shadow zone is due to refraction, while the s-wave shadow zone is due to both refraction and the inability to travel through liquid layers in the Earth Raleigh and Love waves travel on the surface, while S and P-waves travel through the body of the Earth. The "outer core" of the Earth is liquid, not the whole outer part of the Earth.

Why was the discovery of the pulsar planets such a surprise? A) Pulsars are "dead" stars, and we expect the planets to "die"too when the stars die B) The pulsar planets orbit so close to the pulsar that they would fit inside the progenitor star, that exploded to form the neutron star C) The intense beam of radio waves from a pulsar is though to disrupt anything nearby D) When the progenitor star explodes to become a neutron star, the neutrinos leaving the star cause a chain reaction in all the nearby planets, making them explode too

B) The pulsar planets orbit so close to the pulsar that they would fit inside the progenitor star, that exploded to form the neutron star

Why are there no data points in the bottom right of this diagram? A) Small planets far from their star do not exist in nature B) These planets are small and far from their star, and our telescopes are not sensitive enough to detect them yet

B) These planets are small and far from their star, and our telescopes are not sensitive enough to detect them yet

Why are there no data points in the bottom right of this diagram? (y-axis = planet mass, x-axis = distance from the star) A) Small planets far from their star do not exist in nature B) These planets are small and far from their star, and our telescopes are not sensitive enough to detect them yet with the radial velocity method

B) These planets are small and far from their star, and our telescopes are not sensitive enough to detect them yet with the radial velocity method

How do solar/stellar flares affect planetary atmospheres? A) They increase the size of the atmosphere, since the particles released by the flare are absorbed by the planet B) They decrease the size of the atmosphere, since they heat the upper atmosphere causing atmospheric gas to be lost to space.

B) They decrease the size of the atmosphere, since they heat the upper atmosphere causing atmospheric gas to be lost to space.

A beam of light passes by a black hole and only feels a tiny deflection. How big was its point of closest approach (b) compared to the "event horizon" (Schwarschild radius rs) of the black hole? A) Very close, with b~rs B) Very far, with b>> rs

B) Very far, with b>> rs α = 4GM/(bc2) = 2rs/b Small defletction angle α means b>> rs The further away, the smaller the gravity of the black hole, the smaller the deflection angle.

A star is known to have no magnetic field. Is this star expected to have very strong or very weak flaring activity? A) Strong B) Weak

B) Weak Stellar flares are due to magnetic fields. No field, no flares.

Why would secondary eclipse not be regarded as "direct imaging" of a planet? A) You never see the light from the planets in systems where secondary eclipse occurs B) You don't see the light from the star and planet as separate in an image - you just see the combined light of the two bodies as a point in an image

B) You don't see the light from the star and planet as separate in an image - you just see the combined light of the two bodies as a point in an image You do see the light from the planet right before secondary eclipse and then it is blocked by the star. But they are usually too close together (for close-in planets) to see them as separate.

According to the nebular theory, as an interstellar cloud forms a new star and planetary system it A) expands, cools down, and spins slower B) contracts, heats up and spins faster C) expands, cools down and spins faster D) contracts, heats up and spins slower

B) contracts, heats up and spins faster

For an object supported by degeneracy pressure, the radius ____________ as the mass of the object increases A) increases B) decreases

B) decreases

The radial velocity method is best at detecting orbits A) face on B) edge on

B) edge on

Why can't the clouds on the hot Jupiter called Kepler 7b be made of water, like the clouds here on Earth? A) hot Jupiter atmospheres don't contain H2O B) hot Jupiter atmospheres do contain H2O, but it's too hot for it to condense into droplets C) aliens have advanced weather control systems to avoid cloud formation

B) hot Jupiter atmospheres do contain H2O, but it's too hot for it to condense into droplets

Denver, Colorado is at altitude of 1km. The atmospheric scale is is H=10km. What is the atmospheric pressure in Denver? A) 1 atm B) less than 1atm C) greater than 1 atm

B) less than 1atm The pressure is lower than 1 atm as you go up. The rough formula says P=1atm x e-1/10 =0.9atm.

Did Jupiter and all its moons form from a mini-nebula, similar to thee Sun and the planets? A) yes B) no

B) no

Is the Earth's atmosphere composed of the same gases that were in the protoplanetary nebula and which became the main gases in the Sun? A) yes B) no

B) no The sun, and hence the protoplanetary disk which formed our solar system, were dominated by hydrogen and helium. Our atmosphere is dominated by nitrogen and oxygen

It would an hour for your coffee cup to cool by emitting radiation.Is radiation the cooling mechanism responsible for your coffee cup cooling? A) yes B) no

B) no since it takes your coffee cup only minutes to cool off, it can't be radiation that's the cause and must be something else.

This question is based on Figure 2 from the Marcy et al paper. Does the planet occurence rate vary strongly with distance from the star? Let "strongly" mean vary by a factor of 10, let's say. A) yes, the planet occurence rate varies strongly with distance from the star B) no, the planet occurence rate does not vary strongly with distance from the star

B) no, the planet occurence rate does not vary strongly with distance from the star The plot shows the occurence rate is pretty constant. It drops a bit (by a factor of 2) near the star, by otherwise only varies by

You cannot see the Moon when it is close to the Sun in the sky because A) our eyes do not have sufficient angular resolution to separately see light from the Sun and Moon B) our eyes are not able to see the Moon due to the contrast in brightness of the bright Sun and dim Moon

B) our eyes are not able to see the Moon due to the contrast in brightness of the bright Sun and dim Moon The Sun and Moon are huge on the sky, so our eyes do have sufficient angular resolution to see them as separate objects. However,the Moon is so dim we can't detect it's light when it's too close to the Sun.

Sufficiently cold stars, brown dwarfs and planets are supported by A) thermal gas pressure of electrons and ions B) quantum mechanical degeneracy pressure from electrons

B) quantum mechanical degeneracy pressure from electrons

Electron degeneracy pressure is an effect due to A) classical mechanics B) quantum mechanics C) car mechanics

B) quantum mechanics

Line radiation is a consequence of which laws of motion? A) classical mechanics, e.g. the motion of particles which follow newton's laws of motion F=MA B) quantum mechanics, where objects behave as both particles and waves with a fixed number of wavelengths inside the atom

B) quantum mechanics, where objects behave as both particles and waves with a fixed number of wavelengths inside the atom

An absorption spectrum is produced by A) emission of line photons by a tenuous cloud of gas B) removal of line photons from a continuous spectrum as it passes through a a tenuous cloud of gas

B) removal of line photons from a continuous spectrum as it passes through a a tenuous cloud of gas

When the star blocks the planet it's called a A) transit B) secondary eclipse C) first quarter phase

B) secondary eclipse

The distortion of images due to atmospheric turbulence is called A) speckleorama B) seeing C) believing D) beliebering E) the Hanbury Brown and Twiss effect

B) seeing

In lecture 35, the movie of HR 8799 contains numerous white dots. They are A) planets. every single one of them B) some are real planets, and some are artifacts called "speckles", due to atmospheric turbulence and imperfections of the telescopes mirror C) background stars

B) some are real planets, and some are artifacts called "speckles", due to atmospheric turbulence and imperfections of the telescopes mirror Lecture 35. 4 of the white dots are planets, which show circular motion around the star. the rest of them are "speckles", which appear and disappear irregularly. they can't be background stars, as they would move very very slowly.

In microlensing one detects A) the spatially resolved images arising from lensing B) the increase in the amount of light from the source, for a finite time, and then the brightness goes back to what it started at C) only small lens masses, much smaller than the mass of the sun D) only lensing due to mini-sized black holes

B) the increase in the amount of light from the source, for a finite time, and then the brightness goes back to what it started at

What property of a spherical planet can you measure by taking gravity measurements outside the planet? A) the radius of the planet B) the mass of the planet C) the habitability of the planet

B) the mass of the planet

Where are most of the moons in our solar system? A) the inner, terrestrial planets B) the outer, giant planets

B) the outer, giant planets

Planets orbiting stars can be detected especially easily with microlensing for the special case that A) the star sits on the Einstein ring of the planet B) the planet sits on the Einstein ring of the star C) the planet and star both sit on the Einstein ring of the light source

B) the planet sits on the Einstein ring of the star The image is concentrated near the star's Einstein ring, and so if you put the planet there it has a bigger effect than if you put it elsewhere

Even if an Earth-sized planet had the same temperature as Earth, it could not have liquid water on the surface if A) the pressure is above the triple point of water B) the pressure is below ​the triple point of water

B) the pressure is below ​the triple point of water

Mars is red because A) it is made of the Romulan "red matter" B) the water in Mars' early oceans was broken apart by sunlight, the hydrogen was lost to space and the oxygen rusted the surface rocks C) Mars is a carbon-dominated planet and all the surface rocks have encorporated carbon rather than oxygen, giving them their reddish color

B) the water in Mars' early oceans was broken apart by sunlight, the hydrogen was lost to space and the oxygen rusted the surface rocks

Atmospheric pressure at sea level is determined by A) the weight of the Earth below you B) the weight of the atmosphere above you

B) the weight of the atmosphere above you

The gas giant planets have a mean density (mass/volume) of about 1 g/cc because A) they are mostly made of water, and water always has a density of roughly 1g/cc B) they are mostly gaseous objects made of hydrogen and helium, and the density of these objects depends on how much they have been compressed by overlying material. This just happens to be 1g/cc for giant planet size objects

B) they are mostly gaseous objects made of hydrogen and helium, and the density of these objects depends on how much they have been compressed by overlying material. This just happens to be 1g/cc for giant planet size objects

Compute the density of a solid in which atoms are packed together so much that they are touching.An atom has mass m=10-24g, and radius r=10-8cm. Let's make it simple and say volume V=r3, so mass density ρ=m/r3 . A) ρ=10-24 g/cm3 B) ρ=1 g/cm3 C) ρ=1024 g/cm3

B) ρ=1 g/cm3 density = (10-24g)/(10-8cm)3 = 10-24+3x8 g/cm3 = 1 g/cm^

A moon that gets too close to its planet gets turned into A) a pumpkin B) a star C) a ring system, like Saturn D) a black hole

C) a ring system, like Saturn The tidal force from the planet can break the moon apart, and it will get ground down to small chunks like we see in Saturn's ring system.

how do we know that light contains energy? A) light can drive electrical currents in solar panels B) light can heat the o​bject it hits C) all of the above

C) all of the above

The mass of a sphere of mass density ρ and radius R is M=4πR3ρ/3, which is just the mass density times the volume. If the Earth, Jupiter and the Sun all had the same mass density, what would be their relative masses, written as Earth mass: Jupiter mass: Sun mass. (Hint: these three radii are compared to each other in lecture 16). A) 1 : 10 : 100 B) 1 : 100 : 1000 C) 1 : 1,000 : 1,000,000

C) 1 : 1,000 : 1,000,000 The masses scale as the radii cubed. Jupiter's radius is 10x bigger than Earths and the Sun's radius is 10x bigger than Jupiters. 103=1000, so they are Earth mass : Jupiter mass : Sun mass = 1 : 1,000 : 1,000,000.

What is the transit probability for planet in a 1AU orbit around a Sun-like star (with radius Rsun=1AU/200)? A) 1/2 B) 1/20 C) 1/200 D) 1/2000

C) 1/200 For planet radius much smaller than star radius, the transit probability is Probability = Rstar / separation = 1/200

Question about the article by Batalha. According to the article, the Kepler mission continuously monitored A) 1 star for 1 night B) 1 billion stars for 13.7 billion years C) 190,000 stars for 4 years

C) 190,000 stars for 4 years

Heart-shaped surface features on Mars are probably due to A) Martians looking for love in all the wrong places B) NASA technician using the Mars rovers to build huge, heart shaped dirt mounds to send a special valentine's day message to their significant other C) A combination of impacts, erosion and volcanic activity over time

C) A combination of impacts, erosion and volcanic activity over time

What color is the sky(looking away from the Sun)on a planet with no atmosphere? A) Red B) Blue C) Black

C) Black The sky would be black, or like the night sky. No atmosphere means no light scattered in your direction means you don't see anything from that part of the sky.

The finding of extrasolar planets by NASA's Kepler mission was A) complete surprise. Everyone was shocked B) Lucky. NASA really gambled on this one. C) Expected. We already knew extrasolar planets existed, and we had been detecting them by many different methods before Kepler was launched

C) Expected. We already knew extrasolar planets existed, and we had been detecting them by many different methods before Kepler was launched

Imagine a small body with no atmosphere in the outer solar system, beyond the ice line. Not only does it contain a lot of iron and rock, but also H2O in ice form. We expect the surface of these bodies to be composed of nearly pure A) Iron B) Rock C) H2O ice

C) H2O ice Light things float, heavy things sink. Iron should sink to the center as it has the highest density (8 gram / cc), then rock on top of iron as it has an intermediate density (3 gram / cc), then H2O ice at the surface, since it has the lowest density (1 gram / cc) .

When does the star + planet system give the highest brightness, as seen by the observer at Earth? A) Transit B) Secondary eclipse C) In between transit and secondary eclipse, when neither the star nor the planet is being blocked

C) In between transit and secondary eclipse, when neither the star nor the planet is being blocked Both the star and planet give off light. The maximum you can get is when you get all the light from both. If either one is blocked you get less light.

As an observational field, the study of cosmic sources of high energy gamma-ray radiation began A) In pre-history. Humans have always been able to see the gamma-ray sky B) Once the Wright brothers invented the airplane in 1903 C) In the 1960's, when the first gamma-ray telescope was launched into space, above the atmosphere

C) In the 1960's, when the first gamma-ray telescope was launched into space, above the atmosphere gamma-rays from space are absorbed high in the atmosphere. they could not be observed before gamma-ray telescopes were sent into space.

If a giant star had a luminosity of 104 Lsun, how far away would the Earth have to move to remain at the same temperature?(Tplanet ~ (L/a2 )1/4 ) A) Stay at 1AU B) Move in to 1/100 AU C) Move out to 100 AU D) Move out to 104 AU

C) Move out to 100 AU To keep Tplanet the same, when L increases by a factor of 104, then a2 must increase by 104, which means a must increase by 102 => Must move out to 100AU

A M=Mjup planet is found at 5AU from its Sun-like star, on a nearly circular orbit. What aspect of the condensation or nebular theories of planet formation are in disagreement with this discovery? A) The nebular theory states that planets should be on eccentric (elliptical) orbits since B) that's the shape of orbits in the gas disk The condensation theory states that small rocky planets should be found outside the snow line at 3-4 AU C) None of the above

C) None of the above Nebular theory says orbits should be circular since the gas in the nebular disk is in circular orbits. the condensation theory says gas giants should form outside the ice line at 3-4au. so these are both consistent.

Why was Pluto demoted from planet status? A) The New Horizons mission found that it is "potato shaped", and hence cannot be a planet B) It was found that Pluto's moon Charon was actually bigger than Pluto C) Pluto's gravity was not strong enough to clear the neighborhood of it's orbit of other bodies D) Pluto was found not to orbit the Sun, rather it orbits Jupiter.

C) Pluto's gravity was not strong enough to clear the neighborhood of it's orbit of other bodies

By what method were the pulsar planets discovered? A) Since these planets emit pulsed radio beams, they can be detected as "pulsars" by radio telescopes B) The planets created a gigantic supernova explosion that could be seen all the way across the universe C) The Doppler method, but applied to the time interval between radio pulses rather than the frequency (color) of an electromagnetic wave D) Luck. Pure luck. E) the Greek god Kronos created pulsars and they have been known about in myths since the dawn of recorded history

C) The Doppler method, but applied to the time interval between radio pulses rather than the frequency (color) of an electromagnetic wave

What is a possible scientific explanation for the rise and fall of the oceans due to tides? A) The Earth is a real living animal, breathing water in and exhaling it out twice per day B) The god Thor drinks from a horn that he thinks is filled with wine, but is actually connected to the oceans C) The force of gravity (as described by Newton's theory) from the Moon and Sun exerts a pull on the water.

C) The force of gravity (as described by Newton's theory) from the Moon and Sun exerts a pull on the water.

With the radial velocity method, we can measure A) Maximum planet mass and amount of the surface covered by oceans B) The amount of oxygen in the planet's atmosphere emitted by living matter, as well as the radius of the planet C) The minimum mass of the planet and the size and shape of the orbit D) The minimum mass of the planet and the composition of the planet

C) The minimum mass of the planet and the size and shape of the orbit

Why do the eccentricities of the planets found by the radial velocity method contradict expectations of the nebular model of planet formation? A) Gas giant planets were not expected so close to the star B) The extrasolar planets mostly have very small eccentricity, and this was not expected since the nebular gas disk was very eccentric C) The nebular theory says that planets are formed from gas on circular orbits, so we expect the resulting planets to be on circular orbits too D) Very close-in orbits were expected to be highly eccentric due to tides

C) The nebular theory says that planets are formed from gas on circular orbits, so we expect the resulting planets to be on circular orbits too

Where do free floating planets come from, most likely? A) They all form directly from the collapse of gas clouds, just like stars B) They form like other planets, in the gas disk surrounding the newly forming star. But then the star explodes and the planet is free C) They form like other planets, in the gas disk surrounding the newly forming star. But then a near collision with another planet kicks it out of the solar system, and it is no longer bound to the star D) Rocky planets were created created in the big bang, so they have always been floating around in the universe

C) They form like other planets, in the gas disk surrounding the newly forming star. But then a near collision with another planet kicks it out of the solar system, and it is no longer bound to the star

The cloud of dust orbiting the Sun today gives rise to what observable effect? A) the dust covering my living room floor B) the formation of the planets C) Zodaical light D) significant absorption of the light from the sun, blocking it out during "Zodaical eclipses"

C) Zodaical light

Why doesn't the Earth's atmosphere explode or implode? A) god B) aliens C) a balance of the outward pressure force and the inward gravity force D) the atmosphere is squeezed between the pressure from the ground pushing up and the pressure of space pushing down

C) a balance of the outward pressure force and the inward gravity force

For a planet plus star binary lens, especially large microlensing amplification occurs when the source crosses A) the road to get to the other side B) the galaxy C) a caustic D) well outside the star's Einstein ring

C) a caustic caustics are special positions on the sky, relative to the star and planet, that if the blackground light sources crosses them an especially large amplification occurs.

An object that appears black in reflected light absorbs A) reddish wavelengths of light B) blueish wavelengths of light C) all wavelengths of light

C) all wavelengths of light black is the absence of light. if an object looks black it means it's absorbing all wavelengths of light

The directly imaged planets are made more easily detectable due to A) their large distance from the star means large angular separation, making them easier to resolve with a telescope B) they are young, self-luminous planets, which are much brighter than they would be if they only received heat from the star C) both A and B

C) both A and B

Why does the same astronomical object (e.g. a star, or a planet, or a gas cloud) look so different when observed using different parts of the electromagnetic (EM) spectrum? A) the object can be made of many types of atoms or molecules which radiate at their own specific frequencies of EM radiation, and so you see different atoms/molecules in the different wavelength bands B) at different positions in the object the particle energies (i.e. temperature) can be very different, and the spectrum depends on the temperature of the particles doing the emitting C) both of the above

C) both of the above

Which of these astrophysical phenomena has a light curve resembling that from microlensing? A) planet transit B) exploding star) C) classical nova

C) classical nova planet transit goes down instead of up. exploding star goes up, but doesn't return to where it started (as star no longer there, as it exploded). classical nova goes up for a while, then returns to original brightness

terrestrial planets inside the ice line are formed by A) coagulation of hydrogen and helium gas B) coagulation of solid water (H2O), ammonia (NH3) and methane (CH4) C) coagulation of rock and metal D) he god Zeus. They emerged from his head fully formed. E) pieces of the sun breaking off

C) coagulation of rock and metal

The Juno mission found that which theory for forming gas giant planets is correct? A) the jolly green giant theory B) the direct collapse theory C) condensation ("core accretion") theory D) the theory that planets are formed early in the universe, at the time of the big bang

C) condensation ("core accretion") theory

The process by which heavy elements sink inward and light elements float upward, creating a layered planetary structure, is called A) floatification B) integration C) differentiation

C) differentiation

The process of planetesimal formation starts by what bodies hitting and sticking to each other, forming larger bodies A) hydrogen atoms B) charm quarks C) dust from the interstellar medium D) million solar mass black holes E) kilometer-size asteroids

C) dust from the interstellar medium

(think about this one. I didn't discuss this in class) The astrometric method is best at detecting orbits A) face on B) edge on C) either orientation can be detected

C) either orientation can be detected in the astrometric method, the star moves. it doesn't matter if it's edge on or face on, you can see it move on the sky, and so either one is ok

A transiting planet has mass = 1 Jupiter mass, but radius 1.5 Jupiter radii. This planet is likely made out of​ A) Whiskers on kittens B) turkish delight C) hydrogen-rich gas, but with additional heating to "inflate" the radius D) elements much heavier than hydrogen, but with cooling to "deflate" the radius

C) hydrogen-rich gas, but with additional heating to "inflate" the radius inflated hot jupiters have roughly 1 jupiter mass but radius bigger than jupiter. these planets are thought to be made of light elements, to make their radius as big as possible, but then to also have heating, maybe due to tides, to keep the radius big and prevent cooling and shrinking.

The main chemical building blocks of life, carbon, oxygen, and nitrogen were formed A) inside interstellar gas clouds during star formation B) in the center of the Earth and then ejected onto the surface via volcanism C) in the nuclear burning cores of stars and then ejected into space when they died D) in the Big Bang that created the universe

C) in the nuclear burning cores of stars and then ejected into space when they died

Which wavelength range is best to observe thermal emission from an exoplanet, underneath the glare of light from the star? A) x-ray B) ultraviolet C) optical D) infrared

C) infrared relative to the star, the planet emits the most light in the infrared. The reason is that thermal emission cuts off rapidly for photons with energy greater than the thermal energy (kT), and since the planet has a lower temperature than the star, the planet emits much less light in at shorter wavelengths.

The possibility of other worlds was first considered A) after the invention of the telescope B) only during the past few decades C) many thousands of years ago during ancient times D) at the turn of the 20th century

C) many thousands of years ago during ancient times

On the hot Jupiter called HD 209458b, it is claimed that there is methane (CH4) in the atomsphere. What is the basis for this claim? A) it's just a hunch B) it is written in the ancient texts C) models for light passing through an atmosphere containing both water and methane agree better with the transmission spectrum than models only containing water D) it's known that hot Jupiters have cows, and cow flatulence contains methane E) chemistry tells us that all gas phase carbon must be in methane at the relevant temperatures and pressurs

C) models for light passing through an atmosphere containing both water and methane agree better with the transmission spectrum than models only containing water

How do we know the universe is expanding? A) the summers seem to be getting longer as the universe gets bigger B) the Earth-Sun distance is gradually increasing, causing a pause in global warming C) more distance galaxies move faster away from us D) Jean Grey is driving the expansion of the Marvel universe with her telekinetic powers E) because the night sky is dark

C) more distant galaxies move faster away from us

Asteroids are made of A) H and He B) fluoridated water C) mostly rock and metal with very little ice D) asteroids orbit in Thor's belt, and so they are made of the Asgardian metal uru E) Rock, metal, and also lots of ice

C) mostly rock and metal with very little ice

Microlensing is especially good at detecting A) any mass planet, as long as its very close to the staR B) any mass planet, as long as its very far from the star C) planets near the Einstein ring of the star, which happens to be near the snow line around the star D) hot Jupiters, since they are so big and close to the star

C) planets near the Einstein ring of the star, which happens to be near the snow line around the star

Which part of the electromagnetic spectrum can be detected from the ground (i.e. you don't need to use a space telescope)? A) gamma rays B) ultraviolet C) radio

C) radio

What are the three main reservoirs of small bodies orbiting in the solar system? A) the Sun, the Earth and the Moon B) Io, Europa and Ganymede C) the asteroid belt, the Kuiper belt and the Oort cloud D) Jupiter, Saturn and Uranus

C) the asteroid belt, the Kuiper belt and the Oort cloud

Which of these ideas may explain Juno's findings on the size Jupiter's heavy element core? A) there is no core as Jupiter must have formed by direct collapse B) the core is smaller (in radius) than expected since all the heavy elements floated upward to the surface and were eventually lost to space C) the core was eroded over time by the overlying gas and heavy elements were mixed outward over a larger region D) a giant impact hitting Jupiter (by a doomed planet in the early solar system) was able to mix up the core into a much larger region

C) the core was eroded over time by the overlying gas and heavy elements were mixed outward over a larger region D) a giant impact hitting Jupiter (by a doomed planet in the early solar system) was able to mix up the core into a much larger region

Measurement of the true mass and radius of a planet, as long as it has a thin atmosphere, allows one to infer A) the precise run of density as a function of position over the entire planetary interior B) the number of aliens living on that planet and their intentions toward Earth C) the mean density of the planet (mass/volume), which allows constraints on the bulk composition D) the presence of a thin liquid water ocean like we have here on Earth

C) the mean density of the planet (mass/volume), which allows constraints on the bulk composition

This question is based on the Marcy et al paper. The radii of the planets are measured using the transit method. How are the masses measured? A) the transit method B) the gravitational lensing method C) the radial velocity method D) the transit timing variation method

C) the radial velocity method D) the transit timing variation method

Why can't you see the stars during the daytime? A) the stars cease to exist during the daytime, and pop back into existence at nighttime B) aliens C) the stars are very faint compared to the sun, as seen from Earth D) the finite age of the universe

C) the stars are very faint compared to the sun, as seen from Earth The CONTRAST between the light from the sun and stars is too big for your eye to be able to see the stars under the glare of the sun.

Which if the following discoveries of astronomy suggests that enormous numbers of planets may exist in the universe? A) the laws of physics are the same everywhere B) the universe is very old C) the universe is very large, with huge numbers of galaxies, each containing huge numbers of stars D) there is more dark matter than normal matter

C) the universe is very large, with huge numbers of galaxies, each containing huge numbers of stars

Rogue planets are given that name because A) they are rampaging through the galaxy, destroying everything in their path, like an out of control elephant encountering a fruit stand B) they were in the Star Wars movie "Rogue One" C) they exist apart from their star, like an elephant leaving the herd D) they are scoundrelous, as they are really brown dwarfs trying to confuse us into believing they are planets

C) they exist apart from their star, like an elephant leaving the herd rogue planets are also called free floating planets, since they have escaped from their star and orbit alone in the galaxy

What is the Einstein ring? A) The ring of power wielded by Einstein to control elves, dwarves and men B) The ring from Einstein's high school football team, which he always wore C) A physical collection of mass in a ring shape surrounding a star or planet. This ring of mass is huge, and it bends the light, not the star or planet itself D) The shape of the image produced by the lensing mass, when the light source and lens are well aligned

D) The shape of the image produced by the lensing mass, when the light source and lens are well aligned

Question about the article by Batalha. The average number of small (roughly Earth size) planets in the habitable zone around a small "M-dwarf" star is A) 0.0000005 B) 0.000005 C) 0.005 D) 0.5

D) 0.5 1 out of every 2 M-dwarfs has a habitable Earth-like planet!

If half of all stars ever born in our galaxy had already been turned into white dwarfs, roughly how many white dwarfs are there in our galaxy today? A) 0 B) 1 C) 100 million D) 100 billion E) 100 trillion F) infinity

D) 100 billion The number of stars in our galaxy is ~100 billion, so that's the closest answer.

If the distance between the moon and Earth was suddenly halved, the height of our ocean tides would increase by a factor of A) 2 B) 4 C) 6 D) 8 E) 10

D) 8 The tidal force scales as r-3, where r is the earth-moon separation. So if r becomes smaller by a factor of 1/2, this is putting a 1/2 in the denominator, and (1/2)-3 = 23 = 8

Clouds on Kepler 7b might be made of A) rock B) iron C) water D) A and B

D) A and B

Stars A and B have temperatures of 10,000 K, and 5000 K respectively. If the two stars have the same size, how much energy per second does star A give off compared to star B? A) A gives off 2 times as much as B B) A gives off 4 times as much as B C) A gives off 1/4 times as much as B D) A gives off 16 times as much as B E) A gives off 1/16 times as much as B

D) A gives off 16 times as much as B

Stars A and B have temperatures of 10,000 K, and 5000 K respectively. If the two stars have the same size, how much energy per second does star A give off compared to star B? A) A gives off 2 times as much as B B) A gives off 4 times as much as B C) A gives off 1/4 times as much as B D) A gives off 16 times as much as B E) A gives off 1/16 times as much as B

D) A gives off 16 times as much as B

What factors influence the opaqueness of a gas? A )Gas density B) Distance the light travels through the gas C) Line versus continuum photon D) All of the above

D) All of the above

Why does the radial velocity method only give the minimum planet mass and not the true planet mass? A) The planet mass is smaller when the star is moving toward you than away from you B) Einstein's theory of Special Relativity says that moving objects have a larger mass than objects at rest C) Because the star moves less than the planet D) Because the orbit may not be perfectly edge-on, and only line-of-sight motion causes a Doppler shift

D) Because the orbit may not be perfectly edge-on, and only line-of-sight motion causes a Doppler shift

As discussed in lecture, NASA's Juno mission will be able to test a key piece of condenstation theory: if gas giant planets like Jupiter have a solid core at the center. Other competing theories would have no solid core at the center. How will Juno do this test? A) by measuring aurora from Jupiter's south pole B) by measuring the "whistler waves" created by Jupiter C) by monitoring the great red spot to see if it moves across the surface D) By measuring the gravity field Jupiter

D) By measuring the gravity field Jupiter

What might be evidence that the Earth is round, not flat? A) When the Sun passes between the Earth and the Moon, the Sun's surface looks round as it blocks out the moon B) the Moon's surface has craters on it, and hence the heavens are not perfect as the ancient Greeks believed C) Galaxies are composed of huge numbers of stars D) If the Sun is directly overhead at one latitude, and at the same time not directly overhead at another latitude

D) If the Sun is directly overhead at one latitude, and at the same time not directly overhead at another latitude

As the Sun gets hotter, which rocky planet that is NOT habitable now could become habitable in the future? A) Mercury B) Venus C) Earth D) Mars E) Jupiter

D) Mars All planets from Earth inward will become non-habitable. Mars is exterior to Earth, it's too cold now, but would become warmer as the Sun gets brighter. Jupiter is a gas giant, not a rocky planet.

Fomalhaut's "eye of Sauron" is actually A) Sauron. The real Sauron. Biding his time. Waiting for the precious to reappear. B) a ring of planets surrounding the star C) an alien megastructure D) The equivalent of our zodiacal light

D) The equivalent of our zodiacal light The ring is light from the star reflected off dust grains orbiting the star, just like zodiacal light in our solar system

Why might brown dwarfs not be good hosts for habitable planets? By habitable planet, I mean here that the surface temperature of the planet, which is set by the light from the star, must stay constant within a certain range. If it fell out of that range, then water would freeze (if too little light) or evaporate (if too much light). A) Brown dwarfs burn deuterium, and hence the planet would not have any heavy water B) Brown dwarfs have a much weaker gravity, too weak for planets to orbit around them C) Newton's law of gravity does not apply to brown dwarfs D) The luminosity of brown dwarfs decreases with age E) Brown dwarfs only emit infrared light, and so everyone on the planet would be in the dark all the time

D) The luminosity of brown dwarfs decreases with age

What is the name of the long phase of nuclear burning where hydrogen is converted to helium in the star's core? A) The green giant branch B) The vertical branch C) The convergent giant branch D) The main sequence E) The title sequence

D) The main sequence

Newton's theory of gravity says the gravitational acceleration g measured a distance r from a sphere of mass M is given by the formula g(r)=GM/r2. By measuring orbital motions of a body orbiting this planet, what information can we hope to measure about this planet? A) The total mass of living things on the planet B) The color of the oceans and plant life C) The favorite TV shows of the aliens living on the planet D) The mass M of the planet

D) The mass M of the planet That's all you get from the measured motions if the planet is perfectly spherical. It's the only thing related to the planet in the formula, since G is a constant of nature and r is the orbital radius, which can be any radius outside the planet.

Why don't we see Mercury or Venus block the Sun once per orbit? A) They are always on the opposite side of the Sun from Earth B) It happens too fast for us to notice C) The drop in light is too small for us to measure D) Their orbits are misaligned, and so they go above or below the Sun, as seen from Earth

D) Their orbits are misaligned, and so they go above or below the Sun, as seen from Earth when the orbit is not edge on, the planet will appear to go above or below the star

What is the physical origin of the swirly clouds seen in the Juno missions optical images of Jupiter? A) They are "crop circles" made by Jovian farmers in the crops they planted on the surface of Jupiter B) Surface features created by winds acting on mountain ranges over billions of years C) Bioluminescent algae in Jupiter's vast H2O oceans D) They are weather patterns seen in the cloud layers in Jupiter's upper atmosphere

D) They are weather patterns seen in the cloud layers in Jupiter's upper atmosphere

The Earth's temperature decreases A) When it's dark B) When the moon is not full C) When Helios' chariot has sunk back down into Oceanus D) When cooling by infrared radiation is larger than heating by sunlight

D) When cooling by infrared radiation is larger than heating by sunlight it doesn't have to be dark for the temperature to decrease. this can happen before sundown, when cooling beats heating.

If Mars had no atmosphere at all, how big would the greenhouse effect be on Mars? A) larger than Earth's B) larger than Venus's C) larger than the Sun's D) zero E) infinity

D) Zero The greenhouse effect is where an atmosphere contains certain molecules that trap heat near the ground. So you need an atmosphere for this.

In the news recently there have been discussions of the "9th planet." They are referring to A) Pluto B) the Sun, which has been reclassified as both a planet and a star C) he asteroid Ceres, which is known to have water on its surface and hence to harbor life D) a hypothetical planet, out very far in the solar system, the gravity from which would align the orbits of certain Kuiper belt objects

D) a hypothetical planet, out very far in the solar system, the gravity from which would align the orbits of certain Kuiper belt objects

The Milky Way has about 100 billion stars. Suppose you tried to count these stars at a rate of one per second. .How many years would it take you? Assume there are 10 million seconds per year. A) about a week B) about a month C) about a yer D) about ten thousand years

D) about ten thousand years

What is evidence that there are strong winds going from the day to night side on hot Jupiters? A) As measured by thermal emission, the night side is much hotter than you would expect from just the heat coming out of the hot center of the planet, implying some heat is transported from the day side near the surface. B) The point of maximum thermal emission is not at noon, but is slightly in the afternoon, implying the gas is moving from morning to evening. C) During transit, blue-shifted absorption due to carbon monoxide molecules was observed, implying gas motion from the day to the night side. D) all of the above

D) all of the above

Based on the size and composition of planets in our solar system, where was the "snow line" when the planets formed? A) between Mercury and Venus B) between Venus and Earth C) between Earth and Mars D) between Mars and Jupiter E) between Jupiter and Saturn

D) between Mars and Jupiter

The two classes of fundamental particles in the universe are A) photons and quarks B) electrons and protons C) lords and commoners D) bosons and fermions E) leptons and mesons

D) bosons and fermions Bose-Einstein (boson) and Fermi-Dirac (fermions) are the two types. They differ in how many particles are allowed in each quantum state.

A transiting planet has mass = 1 Jupiter mass, but radius 0.5 Jupiter radii. This planet is likely made out of A) Brown paper packages tied up with strings B) nougat C) pure hydrogen D) elements much heavier than hydrogen

D) elements much heavier than hydrogen

A red chair appears red to the eye because A) it emits red light. B) it transmits red light. C) it absorbs red light. D) it reflects red light. E) all of the above

D) it reflects red light most objects around you (aside from the sun and lightbulbs) only reflect light. if white light hits an object and the reflected light looks red, it's because red light was reflected and other wavelengths were absorbed.

The secondary eclipse depth is smaller than the transit depth by the ratio of star and planet A) radii B) diameters C) orbital separation D) temperatures

D) temperatues In the secondary eclipse measurement, we compare the thermal emission from the dayside of the planet to the star. The thermal emission, for long wavelengths, is proportional to temperature

Which specific aspect of condensation theory is being tested by NASA's Juno mission? A) dust particles hit each other and stick to make larger solid particles B) stars and planets form from collapsing gas clouds C) solid planet cores are made of rock and iron inside the snow line, and are made of rock, iron and water outside the snow line D) that gas giant planets form by first forming a large terrestrial planet core and then bringing gas in on top of it from the nebula (accretion disk)

D) that gas giant planets form by first forming a large terrestrial planet core and then bringing gas in on top of it from the nebula (accretion disk)

An early experiment which confirmed Einstein's theory of general relativity was that A) the Sun emits light B) the Sun absorbs light C) the Sun bends the path of light, so that background stars would appear to be closer to the Sun than they actually are D) the Sun bends the path of light, so that background stars would appear to be further away from the Sun than they actually are

D) the Sun bends the path of light, so that background stars would appear to be further away from the Sun than they actually are

The Kepler data which indicated that terrestrial planets were losing their atmospheres was A) transit lightcurves B) changing radius from one transit to another C) the reflected and thermal emission from Kepler 7b as a function of orbital phase D) the measured radii of many planets which shows a lack of planets in a certain size range near ~1.5 Earth radii, and the presence of planets with slightly larger and smaller radii E) the large and changing transit depths seen from the Tabby's star and the exoplanet ring system

D) the measured radii of many planets which shows a lack of planets in a certain size range near ~1.5 Earth radii, and the presence of planets with slightly larger and smaller radii

What is the definition of a star's habitable zone? A) the range of distances from the star where planets with life have been detected B) the range of distances from the star where rocky planets can form C) the range of distances from the star where organic molecules can be stable on the surface of a suitable planet D) the range of distances from the star where liquid water can be stable on the surface of a suitable planet

D) the range of distances from the star where liquid water can be stable on the surface of a suitable planet

If the transit probability is P=1/100, how many stars will have to be searched before 1000 transiting planets are found, on average? A) 10 B) 100 C) 1,000 D) 10,000 E) 100,000

E) 100,000 number found = probability of finding around each star times number of stars searched

Which of the following may cause the measured spectrum of a star to change with time? A) Orbital motion toward or away from the observer B) "Thermal noise" in the telescope C) Hot fluid elements rising and cold fluid elements falling near the surface of the star D) Sound waves ringing around in the star E) All of the above

E) All of the above see slides for c and d. radial velocity produced by orbital motion is what we're mainly interested in. "thermal noise" was discussed in chapter 2 of Johnson's book.

What sets the planet's surface temperature? A) Nuclear fusion reactions within the planet B) Nuclear fission reactions within the planet C) Neutrinos from the star hitting the planet D) Heat from decay of dark matter particles E) Heat from the star's light, which depends on the power output of the star, and the distance from the star to the planet

E) Heat from the star's light, which depends on the power output of the star, and the distance from the star to the planet Recall Energy in (from starlight) = energy out (from radiating infrared light) "Equilibrium temperature" Tplanet = Tstar (Rstar / 2d )1/2, Where Tstar is the temperature of the star, Rstar is the radius of the star, and d is the star-planet distance

A Jupiter mass planet makes a star orbit the center of mass with velocity as given by the formula below. Here P is the orbital period. If the smallest radial velocity that can be detected is 1 m/sec, over what range of orbital periods can this planet be detected? A) P less than 3 years B) P greater than 3 years C) P less than 27 years D) P greater than 27 years E) P less than 19683 years

E) P less than 19683 years If P=19683 years, then 19683^1/3 = 27, and the 27 in the denominator cancels the 27 in the numerator to make 1 m/sec.

9 Question about the article by Batalha. A "planet candidate" is defined as an system that looks like it has a planetary transit (decrease in light when the planet passes in front of the star), but has not been confirmed by some other method (e.g.the radial velocity method). The reason it's not called a planet right away is that there are other signals ("false positives") that look like a planetary transit. One example is in "eclipsing binary" star systems, where one star can just barely block the edge of the other star, giving a small transit depth, like a planet would have. Which of the following are listed in the article as astrophysical false positives? A) grazing eclipse of binary stars B) eclipse of a giant star by a main-sequence star C) eclipse of a fore- or background binary near the target as projected on the sky D) transiting planet orbiting a nearby (projected onto the sky) fore- or back- ground star; E) all of the above

E) all of the above

The Greeks had a thought experiment: cut a rock in half, and in half again, and continue this on until eventually you will reach a smallest indivisible piece of matter that can no longer be broken up. What was the name of that smallest possible chunk of matter, that can no longer be broken up? A) mote B) jot C) corpuscle D) speck E) atom

E) atom

If the "nebular theory" of star and planet formation is applied to the first objects forming after the big bang, what would be different due to the fact that the only elements that exist then are hydrogen and helium? A) the gas cloud cannot contract to form the star B) the gas cloud does not conserve angular momentum as it shrinks, so that it does not spin up C) the star that is formed cannot have nuclear fusion reactions as only hydrogen and helium are there D) there is no friction in the accretion disk since heavy elements cause the friction. hence the disk cannot accrete and the star cannot form E) no rocky planets can form

E) no rocky planets can form

Question about figure 1 in the article by Batalha. Comparing the pre-kepler planet discoveries (left) and the kepler discoveries, Kepler was better able to find what kind of planet? A) planets far from the star B) planets with voracious, squidlike creatures C) planets with blue skies and oceans D) big planets E) small planets

E) small planets The big clump of yellow points in the right hand figure are at smaller radius than the pre-Kepler discoveries

The sodium D transit spectrum showed that the planet has temperature increasing upwards. On Earth, the equivalent region of the atmosphere is called the A) troposphere B) stratosphere C) mesosphere D) microsphere E) thermosphere

E) thermosphere On Earth, the temperature increases upward in the stratosphere and thermosphere. It is thought that the layer being observed on hot jupiters is like our thermosphere. This is the layer where x-ray and ultraviolet light from the star is absorbed, making the temperature increase.

Blue light has wavelength smaller than red lightby a factor 2/3 : λblue = (2/3)xλred .How are the frequency(f) and energy(E) of blue and red light related? Hint: E = hf=hc/λ f = c/λ A) Eblue = (3/2)Ered and fblue = (3/2)fred B) Eblue = (2/3)Ered and fblue = (2/3)fred C) Eblue = (3/2)Ered and fblue = (2/3)fred D) Eblue = (2/3)Ered and fblue = (3/2)fred

Eblue = (3/2)Ered and fblue = (3/2)fred Eblue /Ered = λred/λblue=3/2 fblue /fred = λred/λblue=3/2

Briefly explain how the combination of radial velocity and transit observations gives the true planet mass.

For transit observations, you can measure the ratio of planet to star radius, but more importantly here, the inclination of the orbit from the shape of the lightcurve. The inclination, combined with radial velocity, allows you to get the true planet mass, not just the minimum mass.

What is the angular size of your thumb at the end of your outstretched arm?Θ(degrees)=(360/2π)x(size of thumb in cm)/(length of arm in cm)

Me: size of thumb = 2cm length of arm = 3ft x 12inch/ft x 2.5inch/cm = 90 cm Θ(degrees)=(360/2π)x(2)/(90) = 1.3 degrees

In lecture 30 slide 5, a movie was shown of the time-variation of the infrared emission from Earth. Does this Earth look the same in this infrared image as it does in optical images? Why or why not?

The infrared image does not look the same as an optical image. While the atmosphere is transparent in optical light, the lower atmosphere near the ground is opaque in infrared light, and so we see the infrared light emitted from much higher up. The movie resembled the motions of clouds driven along by winds in the atmosphere.

Question about the article by Batalha. What is the primary mission objective of the Kepler mission?

The primary mission objective is to determine the prevalence of potentially habitable, Earth-size planets in the galaxy.

Which spectrum is from an "emission line nebula" (a gas cloud out in space), and which is the absorption line spectrum from a star?

Upward spikes are emission lines. Downward dips are absorption lines

How are planets found using the microlensing method?

When the planet (lens) passes between the background star (light source) and the observer, it deflects light to Earth that we otherwise would not have received, causing an amplification of light for a short time. So we detect the presence of a planet by watching the light from a star and looking for these brightening events.