Astro exam 3
Saturn's rings
- large, bright - icy - very thin- 10 meters in height
How far away would a star with a parallax of 0.2 arcsec be from us? - 2 parsecs - 5 parsecs - 0.2 parsecs - 0.5 parsecs - we need more information to answer this question
5 parsecs
Jupiter's moons :
Io - Europa - Ganymede - Callisto
Why do astronomers today think that we have an asteroid belt and not a planet between Mars and Jupiter? - a planet exploded and broke apart - Io's volcanoes produced asteroids - Jupiter's gravity prevented material in that zone from getting together - the Sun's wind stops "blowing" there - the solar system needed fashion accessories
Jupiter's gravity prevented material in that zone from getting together
Which planets have rings?
Jupiter, Saturn, Uranus, Neptune
The telescope in space that allowed astronomers to find thousands of exoplanets and exoplanet candidates by making very careful measurements during a planet transit was called: - Kepler - Voyager - Transitor - New Horizons - InSight
Kepler
Which law do astronomers use to determine the masses of the stars in a spectroscopic binary system? - Wien's Law - Kepler's Third Law - Stefan-Boltzmann Law - Hubble's Law - Jenny Craig's Law
Kepler's Third Law
Between 1992 and today, astronomers using large telescopes have discovered many icy pieces that orbit in the same region as the orbit of Pluto. These are believed to be members of the - asteroid belt (which has escaped) - Kuiper belt - Oort cloud - ring around Pluto - the rock and roll band called Bill Haley and the Comets
Kuiper belt
The world in the solar system that is most active volcanically is: - Earth - Neptune - Io - Mars - Ganymede
Lo
Which of the following types of star is the coolest (has the lowest surface temperature)? - O - A - M - F - G
M
Which of the following worlds does NOT have a ring? - Jupiter - Saturn - Uranus - Pluto - Neptune
Pluto
When two objects in orbit have periods of revolution that are simple ratios of each other (such as 1 to 2 or 1 to 3) we say that we have: - an occultation - a conjunction - a resonance - a tidal stability limit - a traffic problem
a resonance
Two stars that are physically associated (move together through space) are called - double stars - main sequence stars - brown dwarf pairs - first contact stars - binary stars
binary stars
the sun's layer
core radiative zone convection zone photosphere chromosphere corona
When an astronomer rambles on and on about the luminosity of a star she is studying, she is talking about: - what color the star is - the total amount of mass in the star - the star's apparent size (the size seen from Earth) - how much energy the star gives off each second - the elements she can see in the star's spectrum
how much energy the star gives off each second
The most common element in the Sun is - helium - iron - hydrogen - water - nitrogen
hydrogen
A main difference between asteroids and comets is that asteroids are mostly made of rock and comets are mostly made of - metals - carbon compounds - ice - vapor (gas) - you can't fool me, astronomers don't really know what comets are made of
ice
Which of the following characteristics of a single star (one that moves through space alone) is it difficult to measure directly? - its apparent brightness - its temperature - its chemical composition - its mass - you can't fool me, all of these are quite easy to measure directly
its mass
Most of the stars we can see with the unaided eye from Earth are - intrinsically fainter than the Sun - very close to us (among the closest stars) - more luminous (intrinsically brighter) than the Sun - only visible to our eyes because they actually consist of three or more stars blending their light together - undergoing some sort of explosion which makes their outer layers unusually bright
more luminous ( intrinsically brighter) than the sun
Today we realize that the source of energy for the Sun is a process called - nuclear fusion - Kelvin-Helmholtz contraction - mechanical to thermal energy - conversion - radioactivity - dilithium crystal moderation
nuclear fusion
Today we realize that the source of energy for the Sun is a process called - nuclear fusion - Kelvin-Helmholtz contraction - mechanical to thermal energy conversion - radioactivity - dilithium crystal moderation
nuclear fusion
As astronomers use the term, the parallax of a star is - one half of the Doppler shift due to its radial velocity - always equal to 1 AU - one half the angle that a star shifts when seen from opposite sides of the Earth's orbit - the time it takes a Cepheid variable star to go through one cycle of its brightness changes - the time it takes for a star to move one second of arc of proper motion
one half the angle that a star shifts when seen from opposite sides of the Earth's orbit
Where in the Sun does the fusion of hydrogen occur? - only in the core - only near the photosphere (its visible surface layer) - pretty much throughout the entire body of the Sun - only in the layer where there is a lot of convection going on - nowhere
only in the core
The material inside the Sun is in the form of a - solid - liquid - plasma - a ball of iron atoms c. none of the above
plasma
Saturn's ring particles are composed mainly of: - silicate rocks - frozen carbon dioxide - droplets of very cold methane - carbon that has been - compressed until it is highly reflective - water ice
water ice
Callisto
- "classic" cratered iceball - no tidal heating, no orbital resonances - geologically dead
Icy moons
- ice melts at lower temperatures - tidal heating can melt internal ice, driving activity
Ganymede
- largest moon in the solar system - clear evidence of geological activity - tidal heating
Saturn's moon Titan
- only moon in the solar system to have a thick atmosphere - consists of nitrogen, argon, methane, and ethane - Huygens probe provided the first look at its surface in early 2005 - most earth-like environment in the solar system - has liquid hydrology and rocks made of ice
Neptune's moon Triton
- retrograde orbit ( backwards) - evidence of past geological activity
Rocky planets
- rock melts at higher temperatures - only large rocky planets have enough heat for activity
Io
- squishes and stretches as it orbits (heats its interior) - most volcanically active in the solar system
Europa
- young, crater-free but heavily cracked - has a massive subsurface ocean 2-3x the volume of earth's oceans
If everything in the solar system is moving around, why do the Perseid meteors repeat regularly around August 11th or so? - Because the Earth does not move relative to the meteor particles - Because the Earth in its orbit intersects the same swarm of meteor particles at the same time each year - Because the Perseids are not in space at all, but in the upper layers of the Earth's atmosphere - Because August 11th is when the Sun's rays are the warmest, and thus tend to move the meteor particles toward us at the fastest speed - Only astrologers can explain this regularity; astronomers do not understand it
Because the Earth in its orbit intersects the same swarm of meteor particles at the same time each year
After a lot of work, a group of graduate students has finally measured the wavelengths of many dozens of lines in the spectrum of a distant star. If a number of the lines come from molecules such as titanium oxide, the star is likely to be which spectral type: - O - B - A - M - we need more information; lines from molecules can be found in stars of every spectral type
M
The moon Triton orbits which of the planets? - Mars - Jupiter - Saturn - Uranus - Neptune
Neptune
What is the best reason astronomers have come up with to explain why sunspots are cooler and look darker? - Sunspots are holes (less dense regions) in the Sun's photosphere, through which we can see the darker regions of the Sun below - Sunspots are places where the strong magnetic fields in the Sun resist the upward motion of bubbling hot gases from underneath - Sunspots are regions where carbon clouds high above the photosphere gather and these dark clouds block the light from underneath them - Sunspots are regions in the upper chromosphere where there is a lot of coronium, which absorbs light - Sunspots are so mysterious and difficult to explain, astronomers really don't have idea what causes them
Sunspots are places where the strong magnetic fields in the Sun resist the upward motion of bubbling hot gases from underneath
A type of planet that our surveys of exoplanets are revealing around other stars, but we don't have any examples of around the Sun are: - terrestrial planets - jovian (giant) planets - Super-Earth's - dwarf planets - you can't fool me, we have examples in the solar system of all the types of planets our exoplanet surveys are revealing
Super-Earth's
A type of planet that our surveys of exoplanets are revealing around other stars, but we don't have any examples of around the Sun are: terrestrial planets jovian (giant) planets Super-Earth's dwarf planets you can't fool me, we have examples in the solar system of all the types of planets our exoplanet surveys are revealing
Super-Earth's
Which of the following statements about the Sun's photosphere is NOT TRUE? - The photosphere is significantly hotter than all the layers of the Sun beneath it (further inward) - The photosphere is not a solid layer; if a spaceship (that could withstand the heat) fell through it, it wouldn't feel anything when reaching the photosphere - The photosphere is much less dense than our Earth's atmosphere - The photosphere is the layer where the Sun becomes opaque (you can't see through it) - Through a telescope, the photosphere looks mottled or granulated
The photosphere is significantly hotter than all the layers of the Sun beneath it (further inward)
What do astronomers think is the origin of the many irregular moons around the outer planets (irregular meaning they are orbiting backwards and/or have eccentric orbits)? - These moons were likely formed elsewhere and captured by the giant planets - These moons are fragments of a much larger moon around each planet that exploded - These moons were expelled by volcanoes on the surfaces of the giant planets - These moons had an early interaction with the rings of the giant planets and were moved to strange orbits as a result - Astronomers have no idea about why these irregular moons exist; it's a complete mystery
These moons were likely formed elsewhere and captured by the giant planets
How can astronomers measure the age of a meteorite that fell from the skies? - Just like for planets, we measure the age by counting the number of craters on the meteorite - Meteorites all contain metals and the metal conducts electricity better and better as it ages - They measure the amount still left of radioactive materials in the meteorite, and how much has turned into decay products - The age of a meteorite can be found from the angle at which it enters the Earth's atmosphere; so scientists can only get the ages of meteorites they observe falling - There is no way to measure the age of any meteorites
They measure the amount still left of radioactive materials in the meteorite, and how much has turned into decay products
Some objects in space just don't have what it takes to be a star (just like many hopefuls in Hollywood don't.) Which of the following is a "failed star", an object with too little mass to qualify as a star? - a brown dwarf - an M type dwarf - an O-type star - the Sun - any star with high proper motion
a brown dwarf
According to the formula E=mc2, - mass has to travel at the speed of light before it can produce any energy - energy can travel much faster than light (in fact its speed can be the speed of light squared) - a little bit of mass can be converted into a substantial amount of energy - when two masses collide, we always get a lot of light - Einstein was a male chauvinist twice over
a little bit of mass can be converted into a substantial amount of energy
The typical meteor is - about the size of a small one-family house - made of evaporated ices - a small solid particle, no bigger than a pea - visible only from above the Earth's atmosphere - the result of magnetic activity in the upper atmosphere of the Earth
a small solid particle, no bigger than a pea
Which of the following looks the brightest in the sky? - a star with magnitude 10 - a star with magnitude 1 - a star with magnitude 6 - a star with magnitude -1 - you can't fool me, all of the above look equally bright from Earth
a star with magnitude -1
If there are at least a million asteroids, how did spacecraft like Galileo survive their trip through the asteroid belt? - NASA sends its spacecraft above and below the orbits of the asteroids in the belt to avoid collisions - spacecraft use a magnetic repulsion tool to make sure asteroids do not come too close - although there are many asteroids, they are widely spaced (there is lots of space between them) - the known asteroids are typically less than a centimeter across, so they do not represent a danger to spacecraft - you can't fool me, NASA has lost over a dozen spacecraft to collisions with asteroids
although there are many asteroids, they are widely spaced (there is lots of space between them)
Which of the following statements about spectroscopic binary stars is FALSE? - visually we can only see one star - some of the lines in the spectrum are double, with the spacing changing over time - an analysis of the ways the lines in the spectrum change allows us to calculate the star's distance directly - we can use the spectrum to determine the sum of the masses of the two stars - we can often use the changes in the positions of the spectral lines to measure the radial velocity of the stars in the system
an analysis of the ways the lines in the spectrum change allows us to calculate the star's distance directly
Which of the following is NOT a way that the moon Titan probably resembles the Earth? - it has a thick atmosphere - the main constituent of its atmosphere is nitrogen - sunlight interacts with the chemicals on the moon to create a rich mix of organic molecules - it has clouds in its atmosphere - at its surface, the temperature and pressure are just right for water to exist in all three phases (gas, liquid, and ice)
at its surface the temperature and pressure are just right for water to exist in all three phases (gas, liquid, and ice)
Why did it take astronomers until 1838 to measure the parallax of the stars? - because most stars are too faint to see without a good telescope - because the stars are so far away that their annual shift of position in the sky is too small to see without a good telescope - because detecting parallax requires measuring a spectrum, which only became possible in the 1830s - because cepheid variable stars had not been discovered earlier - because no one before then could conceive of the Earth moving around the Sun
because the stars are so far away that their annual shift of position in the sky is too small to see without a good telescope
The rings of the outer planets consist of - sheets of ice that stretch in round planes millions of miles wide around each planet - billions of chunks (of various sizes) that all orbit the equator of each planet - many large moons, about the size of Jupiter's moon Io, all crowded together - subatomic charged particles, all kept in line by each planet's magnetic field - millions of alien spacecraft, some of which occasionally make it to the Earth and pick up humans to experiment on
billions of chunks (of various sizes) that all orbit the equator of each planet
Today, astronomers can measure distances directly to worlds like Venus, Mars, the Moon, or the satellites of Jupiter by - bouncing radar beams off them - using x-ray telescopes - using the Hubble Space Telescope to triangulate with - using Cepheid variable stars that lie behind the planets - sending graduate students out with very long tape measures
bouncing radar beams off them
How did Henrietta Leavitt "calibrate" her period-luminosity relationship for Cepheid variable stars? In other words, how did she make the general idea into a numerical rule? - by finding cepheids in star clusters whose distance was known in another way - because the star closest to us is a Cepheid variable and we know its distance - by noting that the period was related to the luminosity in all stars - by measuring the Doppler shift in the spectral lines of Cepheids as they pulsated - by assuming that the Cepheids that appeared the brightest in the sky were closest to us
by finding cepheids in star clusters whose distance was known in another way
How were the rings of Uranus discovered? - They were seen through a small telescope at the same time the planet was - They were discovered with the Hubble Space Telescope - They were discovered by the Voyager 2 spacecraft when it flew by Uranus - Through the radio waves given off as they interact with the magnetic field - by using the Kuiper Airborne Observatory (the telescope aboard an airplane) to observe Uranus moving in front of a distant star
by using the Kuiper Airborne Observatory (the telescope aboard an airplane) to observe Uranus moving in front of a distant star
More than 75% of the known asteroids: - cross the Earth's orbit at least once as they revolve around the Sun - are made of icy material that is highly reflective - were once part of a planet as large as Jupiter - lie farther out from the Sun than the orbit of Saturn - can be found in a belt between Mars and Jupiter
can be found in a belt between Mars and Jupiter
Coronal Mass Ejections from the Sun have many serious effects on or near the Earth. Which of the following is NOT one of these effects? - disrupting the electronics of satellites - heating the ionosphere and thus expanding the extent of our planet's atmosphere - causing power surges and power outages in parts of the Earth near the poles - causing huge cyclones around the equator of the Earth - exposing astronauts and airplane passengers to increased amounts of radiation
causing huge cyclones around the equator of the Earth
Which part of the Sun's atmosphere is the hottest? - chromosphere - transition region - corona - just above the photosphere - you can't fool me, all these regions are at roughly the same temperature
corona
One of the best proofs that our theory of how the solar system formed is correct is that astronomers now observe - Pluto's orbit, which is not in the plane (or disk) that the other planets orbit in - disks around other stars which show evidence of gaps where - planets may be forming planets that are called "hot Jupiters" - no water in the inner solar system - UFO's with alien astronomy textbooks inside, discussing the same theories
disks around other stars which show evidence of gaps where planets may be forming
When a chunk of cosmic material the size of a golf ball or a baseball hits the Earth's atmosphere it makes a - meteor shower - radiant - fireball - meteorite which breaks into pieces when hitting the ground - trail so faint, there is no chance of our seeing it on the ground
fireball
Which of the following statements about the violent events on the Sun called flares is FALSE? - flares happen more often during solar maximum, and sometimes during those periods, there can be several in one day - a flare can release energy equivalent to a million hydrogen bombs - flares originate in the upper part of the corona, in the regions called coronal holes - astronomers think that flares are connected with sudden changes in the magnetic field of the Sun - the visible light we see from a flare is only a tiny fraction of the energy it releases
flares originate in the upper part of the corona, in the regions called coronal holes
When astronomers say that Ganymede is a differentiated body, they mean that it: - has a northern hemisphere which is different from its southern hemisphere - has more of the larger crater types than the smaller ones - has a magnetic field that is not centered on its axis of rotation - has a heavier core, surrounded by a lighter, icy mantle and crust - has a color that is surprising among outer solar system satellites
has a heavier core, surrounded by a lighter, icy mantle and crust
What features are abundant on Callisto and Ganymede and almost absent on Europa and Io? - volcanoes - markings that show the surface is made of ice - impact craters - lakes and pools of liquid ammonia - rings
impact craters
Astronomers now realize that active regions on the Sun are connected with - the dark regions between the bright granulation cells on the photosphere - loops of magnetic field emerging from the surface of the Sun - the absence of sunspots during a solar minimum - great tropical storm systems in the Earth's atmosphere - changes in the gravitational pull of the Sun over different parts of its photosphere
loops of magnetic field emerging from the surface of the Sun
Stars that lie in different places on the main sequence of the H-R diagram differ from each other mainly by having different: - compositions - internal structure - masses - radial velocities - ways that they formed
masses
The first technique that allowed astronomers to find exoplanets involved: - photographing the planets using infrared waves - looking for the decrease of light from the star during a transit of the planet across its disk - sending a very small spacecraft to the exoplanet to take close-up images - measuring changes in the radial velocity (Doppler shift) of the star caused by the pull of orbiting planets - simply taking a visible light photo of the planet around the nearest star; it wasn't that hard
measuring changes in the radial velocity (Doppler shift) of the star caused by the pull of orbiting planets
Chunks of solid material that survive passing through the Earth's atmosphere and are found on the Earth's surface are called - meteorites - asteroids - meteors - meteor showers - comets
meteorites
Astronomers estimate that about 25 million meteors strike the Earth's atmosphere each day. How come we haven't run out of meteors in the long history of the Earth? - meteors come from dust from the Earth's surface that winds have blown high into the atmosphere; the Earth is so big it has lots of dust - meteors are pieces of dirt left over from the formation of our solar system and from old comets; there is a huge supply of small dirt particles from both sources - meteors are caused by electrical sparking in the Earth's atmosphere and there is a lot of static electricity up there - meteors have only been hitting the Earth's atmosphere recently; they are the result of human pollution of space - this is an unsolved problem in astronomy that has a lot of astronomers mystified
meteors are pieces of dirt left over from the formation of our solar system and from old comets; there is a huge supply of small dirt particles from both sources
Which element plays the same role on Titan as water does on Earth (existing as gas, liquid, and solid)? - carbon dioxide - methane - ammonia - hydrogen cyanide - propane
methane
Where on the H-R Diagram would we find stars that look red when seen through a telescope? - only near the top of the diagram and never near the bottom - only near the left side of the diagram and never near the right - only on the right side of the diagram and never on the left - only near the bottom of the diagram and never near the top anywhere in the diagram
only on the right side of the diagram and never on the left
The Murchison meteorite that was found in Australia in 1969 is important to scientists because it contained - organic materials, such as amino acids - more metal than any other meteorite - large flecks of gold - radioactive elements which we do not have on the Earth - the decomposed bodies of small yellow aliens who were clearly intelligent
organic materials, such as amino acids
You are out on the beach, enjoying the warm sunshine with friends. As you glance up at the Sun (only briefly we hope), the part of the Sun that you can see directly is called its: - corona - photosphere - chromosphere - core - heliopause
photosphere
Which of the following worlds does NOT have a ring? - Jupiter - Saturn - Uranus - Pluto - Neptune
pluto
Loops of ionized plasma that connect sunspot pairs are called - coronae - spicules - plages - flares - prominences
prominences
When energy is first produced by fusion deep in the core of the star, that energy moves outward mostly by what process? - convection - radiation - conduction - theoretical modeling - none of the above
radiation
One way to find a new meteorite is to: - patrol the block on which you live carefully each night for a few years - look for a bright comet in the sky and look where its tail is pointing - search the area beneath or close to the point where a bright fireball was seen to burn out - look near the Earth's equator where our planet's magnetic attraction is the greatest - taste the meatloaf in the college cafeteria late in the week
search the area beneath or close to the point where a bright fireball was seen to burn out
The majority of the moons orbiting the outer (jovian) planets are: - large moons, roughly the size of Pluto or Mercury - small moons orbiting in the same direction that their planet turns - much warmer than the planet they orbit - small moons orbiting in a retrograde direction (opposite to the direction their planet turns and orbits) - not in good working order, since they were made in Bayonne, New Jersey
small moons orbiting in a retrograde direction (opposite to the direction their planet turns and orbits)
The majority of the moons orbiting the outer (jovian) planets are: - large moons, roughly the size of Pluto or Mercury - small moons orbiting in the same direction that their planet turns much warmer than the planet they orbit - small moons orbiting in a retrograde direction (opposite to the direction their planet turns and orbits) - not in good working order, since they were made in Bayonne, New Jersey
small moons orbiting in a retrograde direction (opposite to the direction their planet turns and orbits)
When two light elements collide to undergo nuclear fusion, - the total mass involved increases - the positive charges in the nuclei attract, pulling the nuclei together faster and faster - some of the energy in their mass is released - only one survives; the other turns into a release of pure energy - the result is always to make nuclei of iron
some of the energy in their mass is released
An H-R Diagram plots the luminosity of stars against their: - mass - diameter - surface temperature - age - location in the sky
surface temperature
Astronomers now believe that the differences in composition among the planets reflect what characteristics in the early solar system - orbital speed - temperature - whether or not a planet had rings - the age of the material - none of the above
temperature
Which of the following is not a characteristic that worlds in our solar system have in common: - that the planets all revolve around the Sun in the same direction - that most of the planets spin in the same direction that they revolve - that many of the larger moons go around their planets in the same direction - that the planets' orbits lie in roughly the same plane - that all the planets have solid surfaces on which we can see impact craters
that all the planets have solid surfaces on which we can see impact craters
One region on Earth that has become a rich source of new meteorites in recent decades (including the meteorite from Mars that got famous because some scientists claimed they had found evidence for the building blocks of life on Mars) is: - the Yucatan peninsula of Mexico - Bayonne, New Jersey - the Great Salt Lake - Australia - the Antarctic
the Antarctic
A type of star that has turned out to be extremely useful for measuring distances is - the eclipsing binaries - the Cepheid variables - the main sequence stars - the white dwarf stars - the stars that lie in the constellation of Orion
the Cepheid variables
The large reservoir of comet nuclei far beyond Pluto, from which we believe new long-period comets come into the inner solar system, is called: - the Lowell reservoir - the Oort Cloud - the Kohoutek Cloud - the Alvarez belt - Bayonne, New Jersey
the Oort Cloud
Some years some meteor showers, such as the Leonids, feature many more meteors than at other times. What is the cause of these "meteor storms"? - the dust freed from some comets is clumpy and not evenly distributed along its orbit - how many meteors we see in a given year depends on one which side of the Sun we are on - we get meteor storms at the same time and for the same reason we have more hurricanes on Earth - meteor storms happen when Halley's Comet is near the Earth in its 76-year orbit - no one has any idea about why meteor storms happen; they are a mystery
the dust freed from some comets is clumpy and not evenly distributed along its orbit
Comets change as they approach the Sun in their orbits. Which of the following statements about a comet approaching the Sun is FALSE? - the solid water ice in a comet begins to evaporate just beyond the orbit of Mars - comets close to the Sun can evaporate enough material to become as large or larger than Jupiter - the gravity of the comet nucleus holds onto the evaporated material, and it all eventually freezes back into the nucleus - when the ice evaporates, some dust frozen into the ice is freed up to join the comet's coma and tail - the evaporation is not always even but can occur in spurts (where jets of material are seen moving away from the comet nucleus)
the gravity of the comet nucleus holds on to the evaporated material, and it all eventually freezes back into the nucleus
The measurement of cosmic distances was helped tremendously by the discovery, in the early part of the 20th century, that in Cepheid variable stars, the average luminosity was related to: - their radial velocity - the abundance of hydrogen in their atmospheres - their distance from the Sun - the length of time they took to vary - their parallax
the length of time they took to vary
Ninety percent of all stars (if plotted on an H-R diagram) would fall into a region astronomers call: - the supergiant region - the main sequence - the white dwarf region - the visual region - the twilight zone
the main sequence
Which part of a comet is the DENSEST? - the nucleus - the atmosphere (coma) - the dust tail - the gas tail - the hydrogen cloud
the nucleus
Which of the following pieces of observational evidence does our modern "solar nebula" theory of the formation of the solar system NOT explain directly? - the fact that all the planets revolve around the equator of the Sun in the same direction - the difference in the composition of the terrestrial and jovian planets - the ages of the oldest rocks on Earth, the Moon, and meteorites - the plane of the orbit of Pluto - the existence of comets in the outer solar system made mainly of frozen gases
the plane of the orbit of Pluto
The apparent brightness of stars in general tells us nothing about their distances; we cannot assume that the dimmer stars are farther away. In order for the apparent brightness of a star to be a good indicator of its distance, all the stars would have to be: - at the same distance - the same composition - the same luminosity - by themselves instead of in binary or double-star systems - a lot farther away than they presently are
the same luminosity
Halley's Comet was given that name because Edmond Halley was - the first person to ever see that comet - the scientist who pointed out that the orbit of the comet was such that it should return every 76 years or so - the chief scientist who designed the probe that flew by the comet - the first person to be hurt by pieces falling off the comet - prime minister of England at the time the comet was discovered
the scientist who pointed out that the orbit of the comet was such that it should return every 76 years or so
Astronomers call the vast, rotating cloud of vapor and dust from which the solar system formed: - the Oort Cloud - the Kuiper Belt - the proto-Sun - the solar nebula - Bayonne, New Jersey
the solar nebula
In the formula E=mc2, the letter c stands for - the speed of sound - the speed of an electron around the nucleus - the amount of energy contained in one hydrogen nucleus - the energy of a neutrino emerging from the Sun - the speed of light
the speed of light
Sunspots are darker than the regions of the Sun around them because - they consist of different elements than the rest of the Sun - they are located in the corona and not in the photosphere - they move much faster around the Sun than other materials and thus heat up - they are the shadows of the planets and asteroids seen on the bright surface of the Sun - they are cooler than the material around them (although still very hot compared to Earth temperatures)
they are cooler than the material around them (although still very hot compared to Earth temperatures)
A light curve for a star measures how its brightness changes with - time - distance - mass - radial velocity - age
time
