Astronomy Exam 3 Crash Questions!!!!
From the data given, which star in the table has the greatest luminosity?
58 Ori
Which of the following is the closest to the size of a white dwarf?
Earth
From the data given, which star in the table has the greatest surface temperature
HR 4621
According to Henrietta Swan Leavitt, the Capheid variable stars obey a beautiful relationship that allowed them to be used as "Standard Candles." Which of the following qualitatively describes that relationship?
The longer the period, the larger the luminosity
It is quite surprising to see the stunning images of Pluto that were taken when the New Horizons spacecraft flew past. Instead of being dead, we discovered all the following EXCEPT:
a surface ocean of liquid nitrogen
Which of the following stellar endpoints CANNOT have happened because the universe is only 13.3 Billion years old?
a white dwarf from 0.5 Msun star
The two most abundant elements in the sun are a. nitrogen and oxygen. b. hydrogen and helium. c. sulfur and iron. d. carbon and hydrogen. e. carbon and nitrogen.
b
When light escapes from a black hole, it appears to lose energy. This is known as a. Doppler blueshift b. Gravitational redshift c. Doppler redshift d. conservation of energy e. Gravitational blueshift
b
According to Einstein's theory of general relativity, the force that we perceive to be gravity is really just the warping of the fabric of spacetime. The presence of mass causes this fabric to be warped and the larger the mass, the more it warps spacetime. The strange thing is that time will not pass the same for people in different gravitational fields, according to an outside observer. The greater the warping of spacetime (the stronger the gravitational field) a. does not matter; clocks will always tick in the same way b. the faster the clocks will appear to tick c. the slower the clocks will appear to tick
c
In March 2011, a star which wandered in too close to a black hole was a. completely unaffected by the black hole b. pulled apart to make two smaller stars which now orbit the black hole c. completely ripped apart and briefly flared to be as bright as a trillion suns d. swallowed up in one quick gulp e. flung out of its ogalaxy into intergalactic space
c
Which of the following quantities change significantly during a stars main sequence lifetime?
core composition
If you were to fall feet first into a 10 solar mass black hole, the tidal forces would a. flatten you like a piece of paper b. affect your head more than your feet c. compress you into a tiny sphere d. spaghettify you e. squeeze you like a lemon
d
The magnetic field of the sun is smooth at times, but appears to get tangled over time before getting smooth again. What is the best explanation for this process?
differential luminosity
A "low mass star" has a mass less than **(1 solar mass = mass of our Sun)** a. 0.5 solar masses b. 0.33 solar masses c. 1 solar mass d. 5 solar masses e. 8 solar masses
e
A black hole with a mass between 3 solar masses and 12 (it could be more than this though) solar masses is considered to be a a. primordial black hole b. Kerr black hole c. supermassive black hole d. dwarf black hole e. stellar black hole
e
A kilonova is 1000 times as powerful as a nova and is a cataclysmic explosion from the merger of a. two white dwarfs. b. two black holes. c. two red giant stars. d. one white dwarf and one red giant. e. two neutron stars.
e
A neutron star has more mass than the sun, but is packed into an object only a. 100 miles wide. b. 1000 miles wide. c. 1 mile wide. d. 10000 miles wide. e. 10 miles wide.
e
Convection in the outer layer of Sun can be observed through the appearance of:
granulation
An astronomer observes a globular of stars and constructs an HR diagram like the figure below. What can he or she learn by identifying the spectral class of the region marked "X"?
the age of the cluster
When carbon fuses, it will produce all of the following EXCEPT a. aluminum (Al) b. neon (Ne) c. sodium (Na) d. magnesium (Mg)
a
The escape velocity of the Earth is about 11 km/s. The sun has an escape velocity of 600 km/s. A neutron star can have an escape velocity of 150,000 km/s. What is the escape velocity at the event horizon of a black hole? a. 150,000 km/s b. 300,000 km/s (the speed of light) c. 600,000 km/s (2x the speed of light) d. 450,000 km/s (1.5x the speed of light) e. 200,000 km/s
b
The gases expelled by a low mass star in its red giant phase don't get very far (about 1 light year or so) by the time the star collapses to form a white dwarf. When the radiation excites the gases, they glow and we call them a a. ionization cluster b. planetary nebula c. protostar d. neutron star e. black hole
b
The largest known star is 2 Billion km in diameter, and is known as a hypergiant. What is the name of the largest known star? a. Arcturus b. VY Canis Majoris c. Antares d. Betelgeuse e. Rigel
b
The new field of "multi-messenger astronomy" refers to the idea that we get information from both a. ultraviolet and infrared light. b. light and gravitational waves. c. sound and light. d. light and cosmic rays. e. sound and gravitationally waves.
b
The sun will never be able to fuse carbon in the core, and the force of gravity will compress it into a small ball, only the size of the Earth called a a. red dwarf b. white dwarf c. brown dwarf d. neutron star
b
What makes the Las Cumbres Observatory better than most ground based telescopes? a. The telescope is at the top of La Cumbre peak. b. It is a network of telescopes around the globe that always has at least one telescope in the dark. c. The telescope is four times the size of the Keck observatory. d. They have the highest resolution cameras in the world. e. The cameras are sensitive to both infrared and x-ray light.
b
When multiple star systems are first formed, they may not be fully stable, causing one or more stars to eventually be ejected. Only the stable arrangements survive for a long period of time. Which of the following stars does Phil say "might have" had a companion but we will never really know a. Polaris b. Our sun c. Betelgeuse d. Rigel e. Arcturus
b
When the Las Cumbres Observatory (LCO) began looking for the kilonova, they had preprogrammed galaxies to look at. Which galaxy was the kilovova located in? a. second! b. fifth! c. fourth! d. first! e. third!
b
When the hydrogen in our sun's core runs out, it will begin to collapse and heat up. What will happen in the shell around the core as a result? a. It will get hot enough to fuse helium b. It will get hot enough to fuse hydrogen c. It will contract as well and heat up more d. It will turn to liquid under the extreme pressures
b
The surface temperature of a newly formed white dwarf can be about a. 6,000 K b. 1,000,000 K c. 10,000 K d. 100,000 K e. 10,000,000 K
d
A much larger, but cooler star than our sun would be a ____________________ star. a. red dwarf b. white dwarf c. red supergiant d. blue supergiant
c
According to Phil, the only way we know how to get accurate stellar masses is a. when they are incredibly bright b. when they have hydrogen absorption lines c. when they are in a binary system d. when they have iron absorption lines e. when they are incredibly dim
c
According to Phil, when compared to lower mass stars, higher mass stars go out a. with a whimper b. with a whisper c. with a bang d. silently e. with an explosion
c
After the main life of the sun, where it fuses hydrogen in the core, it will become a a. red dwarf b. blue giant c. red giant d. green dwarf
c
All of the following are layers within the sun EXCEPT a. core b. radiative zone c. conduction zone d. convection zone
c
If we study the light curve, we can see that the dips in brightness are not always the same "depth". What is the cause for a deeper dip? a. The larger star is hotter and is passing in front of the cooler, smaller star. b. The hotter star passes in front of the cooler star. c. The cooler star passes in front of the hotter star. d. The stars vary in brightness and the deeper dip corresponds to a decrease in the overall brightness of the system. e. The larger star is cooler and is passing behind the smaller hotter star.
c
Inside the core of a star, 4 protons (Hydrogen nuclei) join together to make a. two helium nuclei b. four helium nuclei c. one helium nucleus d. one lithium nucleus
c
Most of the elements on the periodic table are produced by the expanding shockwave from a type II supernova. This process is known as a. nuclear fission b. nuclear fusion c. explosive (supernova) nucleosynthesis d. stellar nucleosynthesis
c
Optical Double Stars are two or more stars that appear next to each other in the sky. Which of the following statements is true about them? a. They are always close together in space. b. They are never binary stars. c. They could be close together in space, but more carfeul observation is needed to determine if they are. d. They are temporarily bound together with a gravitational force. e. They are never close together in space.
c
Our sun is "powered" by the fusion of hydrogen atoms into a. bigger hydrogen atoms b. carbon atoms c. helium atoms d. iron atoms
c
The most bizarre binary system that Phil knows about is 4U 1820-30 which orbit each other with a period of only 685 seconds (11.4 minutes) and is composed of a neutron star and a a. red supergiant b. yellow dwarf c. white dwarf d. red giant e. blue supergiant
c
A magnetar has incredibly powerful magnetic fields. as much as a quadrillion times the magnetic field strength of our sun. Occasionally these will have star quakes, like earthquakes that can release energy in a flare a trillion times stronger than a typical solar flare. The amount of energy released in one of these events is the same as the sun releases in a. 50 year b. 2.5 Million years c. 250 years d. 250,000 years e. 1,000 years
d
A neutron star packs a mass of more than our sun into the size of a. the North American Continent b. the state of Arizona c. the planet Earth d. a small city e. a basketball
d
A star with 8 Solar Masses will fuse hydrogen for a. about 10 Million Years b. about 5 Billion Years c. about 1 Million Years d. about 100 Million Years e. about 1 Billion Years
d
A star with a spectrum having a peak in the green part of the visible spectrum would appear ___________ to our eye. a. green b. blue c. red d. white e. black
d
How far away was the kilonova event? a. 130 trillion ly from Earth. b. 1.3 ly from Earth. c. 130 billion ly from Earth. d. 130 million ly from Earth. e. 130 ly from Earth
d
This force is what prevents a white dwarf from collapsing any further under the influence of gravity. a. neutron degeneracy pressure b. radiation pressure from nuclear fusion of helium c. radiation pressure from the nuclear fission of carbon d. electron degeneracy pressure e. proton degeneracy pressure
d
Two stars which are the same intrinsic brightness, but star A is twice as far away as star B. How do their brightnesses compare to our eyes? a. star A is twice as bright as star B b. star A is four times as bright as star B c. star A is 1/2 as bright as star B d. star A is 1/4 as bright as star B
d
When a high mass star finishes fusing the hydrogen in the core and begins fusing helium in the core it will become a a. red giant b. blue supergiant c. blue giant d. red supergiant
d
When the sun is a red giant, what will happen to the Earth? a. The Earth will freeze because the surface of the sun is cooler. b. The Earth may move to a larger radius because the sun will exert a weaker force of gravity, and will freeze because it is colder further out in the solar system. c. The Earth will fall into the sun because the force of gravity will increase. d. The Earth may move out to a larger radius because the sun will exert a weaker force of gravity, but will become a molten ball much like when it was formed. e. The Earth will very likely be ejected from the solar system, along with the matter being expelled by the sun.
d
It wont happen on its own, but in order to form a black hole with a star the mass of our sun, it would need to be compressed to a diameter of only a. 100 km b. 60 km c. 20 km d. 50 km e. 6 km
e
The brightest star in the night sky, Sirius, has a very faint companion star that can be seen with a telescope. Which of the following telescopes can see the binary actually appear as brighter than Sirius? a. Microwave telescope b. Visible light telescope c. Radio telescope d. Ultraviolet telescope e. X-ray telescope
e
The sun's magnetic field is evident in the looped shapes of a. solar flares. b. sunspots. c. the corona. d. granules. e. prominences.
e
What is the number of white dwarfs that have been found in our galaxy? a. nearly 500 b. slightly over 1000 c. slightly more than 100 d. only 1 has been found, about 9 light years from us called Sirius B e. over 10,000
e
What will happen to the Earth when the sun becomes a black hole? a. It will continue to orbit the black hole at its current radius b. it will get a little closer because the light from the sun will no longer be pushing on it c. It will be sucked in because of the sun's increased gravitational field d. it will drift away from the sun due to the weakening of the gravitational field e. Bad question. The sun will never be able to form a black hole
e
How can we tell that two stars are nearly identical? a. spectroscopy b. parallax c. transits d. eclipses e. doppler shift
a
At the exact same time that LIGO and Virgo had their detections, NASA's Fermi satellite detected a. sound waves. b. a neutrino pulse. c. gamma rays. d. radio waves.
c
A star spends most of its life on the Main Sequence a. fusing hydrogen into helium in the core b. fusing hydrogen to helium in a shell around the core c. splitting helium into hydrogen in the core d. splitting helium into hydrogen in a shell around the core e. burning hydrogen and oxygen to chemically form water
a
A star with a mass of about 8 solar masses will a. be able to fuse carbon in the core b. never be able to fuse helium c. collapse under the intense force of gravity until it forms a grey dwarf d. use all of its fuel in about 10 million years and then explode
a
According to Wikipedia - Stellar Nucleosynthesis, all of the following are produced in a kilonova explosion EXCEPT a. Aluminum (Al) b. Platinum (Pt) c. Gold (Au) d. Uranium (U) e. Silver (Ag)
a
As the Earth goes around the sun in orbit, we can measure shifts in the position of nearby stars relative to their background stars. This is called a. parallax b. Doppler shift c. star migration d. proper motion e. transient motion
a
Herzsprung and Russell created a chart which compared the Luminosity of a star to its ______________ and discovered that there was a pattern. a. Temperature b. Brightness c. Apparent Magnitude d. Absolute Magnitude
a
If a star has less than 20 Solar Masses when it collapses, then it will form a compact object about 20 km in diameter called a __________________ with part of the matter, and the rest of the matter will explode outward in a Type II supernova. a. neutron star b. white dwarf c. black hole d. red giant e. brown dwarf
a
If you could magnify an atom to be 100 meters across (the size of a football field), then the nucleus would be about the size of a. a marble b. a grain of sand c. a baseball d. a basketball e. a football
a
Mizar and Alcor (also called the horse and rider) have been known since ancient times. Which of the following statements is NOT true about them. a. One of the stars will be exploding (supernova) soon. b. They were once used as a vision test. c. They are held together with a force of gravity. d. They are a multiple star system with a total of six stars orbiting each other. e. They are found in the Big Dipper.
a
On August 17, 2017 the LIGO detectors in the US and the Virgo detector in Italy detected a. a disturbance in spacetime called a gravitational wave. b. a seismic wave on the Martian surface. c. a seismic wave on the lunar surface. d. a seismic wave beneath the Martian surface.
a
Our sun will become a white dwarf with a mass of about half its original mass and a size of about a. 1/100 its original diameter b. 1/2 its original diameter c. 1/20 its original diameter d. 1/10 its original diameter e. 1/4 its original diameter
a
Sunspots a. are cooler than their surroundings. b. are regions where material is rising from below the photosphere. c. are the result of convection. d. produce spicules. e. are generally found near the poles of the sun during sunspot maximum.
a
The brilliant astronomer Cecelia Payne Gaposhkin found that stars are mostly made of a. hydrogen and helium b. hydrogen and methane c. hydrogen and oxygen d. hydrogen and carbon e. helium and nitrogen
a
The mnemonic, Oh Be A Fine Guy/Girl Kiss Me gives the correct order of stellar classification as O,B,A,F,G,K,M. Which star is the hottest star in this classification system? a. O b. F c. A d. G e. M
a
What happens when a white dwarf steals enough mass from its companion to exceed 1.4 solar masses? a. it fuses nearly all of its carbon at once and becomes a supernova. b. It will collapse and form a black hole. c. It will split into two smaller stars, about 0.7 solar masses each. d. It will become a red giant. e. it releases a large amount of energy called a nova and then can collect more mass.
a
Which one of the following types of binaries would best be studied by watching the light curve of the system (the total light from the system). a. Eclipsing binary. b. Spectroscopic binary. c. Visual binary.
a
White Dwarfs emit ultraviolet and even x-ray radiation, but have low magnitudes because they do not produce a lot of light a. but curiously do not emit much visible light b. because they are relatively cool, similar to our sun c. and have large magnitudes because they produce a lot of light d. and they are also the brightest gamma ray sources in the galaxy
a
"Ionized" hydrogen gas means that a. the protons and the electrons are together making neutral atoms b. the electrons have been ripped away from their protons c. the electrons and protons combine to form neutrons d. the hydrogen atoms have fused to form helium nuclei
b
A "high mass" star is a star which begins with a. more than 12 Solar Masses b. more than 8 Solar Masses c. more than 3 Solar Masses d. about 5 Solar Masses e. about 6 Solar Masses
b
A parsec is a distance used by astronomers to describe distance. Theoretically a star which is one parsec away would have a parallax angle of one arc second. A parsec is also a. one light year b. 3.26 light years c. 4.2 light years d. 11.1 light years e. 2 light years
b
A star with a mass between 8 and 20 solar masses will undergo nuclear fusion in the core all the way up to iron (Fe) before exploding in a supernova explosion. If the remaining core mass is more than 1.4 solar masses and less than 2.8 solar masses then this incredibly dense object will form. a. a white dwarf b. a neutron star c. a proton star d. an electron star e. a black hole
b
As a graduate student, Jocelyn Bell Burnell (and her advisor Antony Hewish who ultimately received a Nobel Prize for this work in 1974) is credited with the discovery of the first rapidly rotating neutron star, which she detected with a radio telescope array. The rapid rotation, together with the powerful magnetic field produces twin beams of energy whcih radiate away from the object. We call this a a. spinor b. pulsar c. hydrodynamic engine d. rotator e. cosmic spinner
b
Because they are incredibly dense objects, 1 cubic centimeter of a white dwarf mass (about the size of a six-sided die) is about a. a million tons b. a million grams (one metric ton) c. 100 kg (0.1 metric tons) d. a billion grams (one thousand metric tons) e. 100 million grams (one hundred metric tons)
b
Einstein's formula E = mc2 relates how the matter in the sun is converted into pure energy to support the sun. The letter c is the a. Chandrasekhar limit b. speed of light c. cost of the energy d. charge of an electron
b
Eratosthenes was able to determine the size of the Earth by knowing that at noon on the Summer Solstice, that light hit the bottom of the well in the city of a. Alexandria b. Syene c. Rome d. Athens e. Cairo
b
In the 1960s, astronomers were able to bounce radar pulses off of ______________ to establish a precise value for the Astronomical Unit a. Mercury b. Venus c. Moon d. Mars e. Jupiter
b
Lower mass stars cannot ever achieve a high enough temperature and pressure to ignite Carbon fusion. What is the temperature needed to fuse carbon in a star core? a. 10,000,000K b. 500,000,000K c. 1,000,000K d. 100,000,000K e. 200,000,000K
b
Most of the visible light we see coming from the sun originates from the a. chromosphere. b. photosphere. c. corona. d. sunspots. e. magnetic field.
b
Much of the red color in planetary nebulae comes from hydrogen. The green color in nebulae was originally thought to come from an unknown element, named Nebullium, but in the end it turns out it comes from ordinary a. mercury (Hg) b. oxygen (O) c. carbon (C) d. nitrogen (N) e. neon (Ne)
b
One of the primary reasons that kilonvoae have not ever been seen is that they fade very quickly in only a. a few years. b. a few days. c. a few minutes. d. a few months. e. a few hours.
b
One possible explanation for the weird, beautiful and fantastic shapes of planetary nebulae is that they a. spun faster at first then slowed as material was ejected b. swallowed some their planets which then stirred the interiors of the stars c. rotate faster at the equator than the poles, causing material to be flung away from the equator faster d. are affected somehow by the intense magnetic field of their star e. are caused by the precession of the axis of the star
b
Planetary nebula typically glow for a. about 100 years b. about 1000 years c. about a million years d. about 10 million years e. about 100 million years
b
Stars were initially classified in terms of the strength of their a. Carbon lines b. Hydrogen lines c. Helium lines d. Nitrogen lines e. Argon lines
b
The brightness of a star follows in inverse square law in relation to the distance from the star, very similar to the formula for a. blackbody radiation b. Newton's Universal Law of Gravitation c. Wien's Displacement Law d. Kinetic Energy
b
The density of neutron stars matter, neutronium, is about 400 million metric tons per cubic inch. Phil tells us this is like squishing _________________ into one single six-sided die. a. all of the automobiles on the entire Earth b. all of the automobiles in North America c. all of the people on Earth d. all of the water on Earth e. all of the automobiles in China
b
Which of the following statements is true about high mass stars a. They have a higher mass, and fuse at a higher rate as lower mass stars but they still live longer. b. They have a higher mass, but fuse at much higher rate than lower mass stars so they have shorter lives. c. They have a higher mass, but fuse at slower rate than lower mass stars so they have longer lives. d. They have a higher mass, but fuse at about the same rate as lower mass stars so they have longer lives.
b
As the high mass star fuses one fuel, the "ash" of the fusion reaction will accumulate in the core, and fusion in the core will stop. What happens to the core at that point? a. the core expands because of the fusion taking place outside the core b. the core material will begin to circulate and bring fresh fuel to the core c. the core shrinks and heats up until the ash is finally able to fuse d. the core shrinks and cools until the ash solidifies
c
At the core of nearly every galaxy is higher mass black hole. The first one that was conclusively observed is the one at the center of the Milky Way with a mass of more than 4 million solar masses. These black holes at the centers of glaxies are known as a a. dwarf black hole b. stellar black hole c. supermassive black hole d. primordial black hole e. Kerr black hole
c
Every second, the sun is converting 700 million tons of hydrogen gas into a. 700 million tons of hot hydrogen plasma b. 700 million tons of helium c. 695 million tons of helium d. 695 million tons of hot hydrogen plasma
c
For a short while, astronomers were unsure of the source of regular radio pulses from space and gave them the name LGMs. What does LGM stand for? a. Laser Green Medallions b. Light Guided Missiles c. Little Green Men d. Light Generated Minutia e. Lower Generation Manifestation
c
Hotter stars tend to put out more __________ light than __________ light. a. red, green b. red, blue c. blue, red d. blue, violet e. infrared, ultraviolet
c
The reason a low mass star can live so long is that a. it fuses its hydrogen fuel more quickly b. the fusion takes place throughout the star c. it fuses hydrogen fuel slowly and the region outside the core is convective so the fuel can make it back to the core where it will eventually be used d. it gets new fuel from neighboring stars e. it does not mix very well so it only uses a small fraction of its mass
c
The stellar classification system has each letter broken down into 10 different classifications. The precise classification of our sun is a. G0 b. G3 c. G2 d. A6 e. A0
c
These are small but hot stellar remnants found in the lower left of the H-R diagram. a. red dwarf b. red giant c. white dwarf d. red supergiant
c
What happens when protons and electrons are pushed together under extreme pressures? a. they annihilate each other and release light energy b. they form a positron electron pair plus two neutrinos c. they merge and form a neutral neutron d. they merge and form a negatively charged neutron e. they form a positively charged prion
c
When a neutron star is formed, this force is strong enough to oppose the incredibly strong force of gravity trying to collapse it further. a. electron degeneracy pressure b. proton degeneracy pressure c. neutron degeneracy pressure d. neutrino pressure e. radiation pressure
c
When the sun begins fusing helium in its core, the process is highly unstable and Phil says the sun will go through a series of a. orgasms b. reflexisms c. paroxysms d. unfortunate events
c
Which of the following is closest to the core temperature of the sun? a. 5800 Kelvin b. 1,000,000 Kelvin c. 15,000,000 Kelvin d. 300,000 Kelvin e. None of the above
c
With higher pressure, the nuclear fusion process occurs more frequently, releasing more energy. The lower the mass of a star, the a. shorter its life will be b. hotter its core will be c. longer its life will be d. more energy will be released by fusion in the core e. greater the pressure will be in the core
c
According to Phil, the method of measuring parallax angle allows us to determine the postions of stars out to about a. one light year b. ten light years c. 100 light years d. 1000 light years e. 1000000 light years
d
Conservation of momentum is a law of physics that says that if a star is rotating before it collapses, then when it collapses it will a. rotate slower after the collapse b. continue rotating at the same rate c. stop rotating d. rotate faster after the collapse e. change its axis of rotation after the collapse
d
If a pair of binary stars are so close together that we cannot see them as separate even with the largest telescope, then we can use spectroscopy to determine that two or more stars are present. Spectroscopic binaries rely on which of the following principles to distinguish the two stars. a. The light of the brighter star is dimmed when the other star passes in front of it. b. Take a photo of it and use digital zoom until we can finally see them as separate. c. The light of the dimmer star is blue-shifted when it is behind the brighter star and red-shifted when it is in front of the brighter star. d. The Doppler effect. One of the stars will be moving away and its light red-shifted, while one will be moving toward us and its light will be blue-shifted. e. The Doppler effect. Both of the stars will be red-shifted or blue-shifted depending on how the Earth is moving.
d
If a supernova remnant core has a mass greater than 2.8 solar masses, then what force will be able to stop gravity from collapsing the core? a. electron degeneracy pressure b. radiation pressure c. neutron degeneracy pressure d. nothing; it is not possible to stop gravity in this case e. neutrino degeneracy pressure
d
In order to determine (indirectly measure) the distances from the other planets to the sun, first required us to know the a. exact size of the Sun b. exact size of the Earth c. time it takes the Earth to go around the sun d. distance between the Earth and the Sun e. speed of light
d
Instead of releasing energy, the fusion of _________________ absorbs energy and causes the core to collapse completely. a. argon (Ar) b. oxygen (O) c. carbon (C) d. iron (Fe) e. silicon (Si)
d
The precise value of the Astronomical Unit is a. 148,510,000 km b. 150,205,000 km c. 149,000,000 km d. 149,597,870.7 km e. 148.237.410 km
d
The sun is more than 100 times the size of the Earth, over 300,000 times the mass of the Earth and able to fit more than 1 million Earths inside its volume. The Sun is made of a. solid b. liquid c. gas d. plasma
d
A really low mass red dwarf can live as long as a. a billion years b. 5 billion years c. 10 billion years d. 100 billion years e. a trillion years
e
