Overview and Formation of the Solar System

1. What do we mean by the Solar System?
A)..The planets and their moons.
B)..The Sun, the planets, and their moons.
C).. The Sun, the planets, their moons, and the minor objects like comets and asteroids.

2. What holds it together?
A)...Magnetic forces
B)...Electric forces
C)...Gravity

3. What is the largest object in the Solar System?
A)... The Sun.
B)...Jupiter.
C)... The Earth.
D)...Saturn.
E)...Pluto.

4. What do we call the large objects that move in orbit around the Sun?
A)...moons.
B)... planets.
C)... planetesimals.
D)... microtesimals.
E)...Macrotesimals.

5. How do the planets near the Sun differ from those farther out?
A)... The ones nearest the Sun are generally biggest.
B)...The ones nearest the Sun are generally smallest.
C)... The ones nearest the Sun spin fastest.
D)... The ones nearest the Sun contain more hydrogen.
E)... The ones farthest from the Sun contain a higher proportion of iron.

6. About how old is the Solar System?
A)... 10 million years.
B)... 10 thousand years
C)...5 billion years
D)...5 trillion years.
E)...50 million years.

7. How do we know how old the Solar System is?
A)... Astronomers exploring the Moon have found tablets left by aliens that tell us.
B)... Products of radioactive decay in old rocks.
C)... The amount of water in old rocks.
D)...The size of a planet.
E)... Both C and D.
8. From what did the Solar System form?
A)... A comet captured by the Sun.
B)...The debris from two colliding stars.
C)...An interstellar cloud.
D)... Debris from two colliding galaxies.
E)...Material that fell into a black hole and which was then ejected in a narrow beam.

9. What are interstellar clouds made of?
A)...Sugar and spice and everything nice.
B)...Swarms of uranium atoms that gradually decay into water.
C)...Iron and carbon atoms, mostly.
D)...Mostly hydrogen and a small amount of dust grains.
E)...Mostly helium and mercury droplets.

10. What component of the clouds became the inner planets?
A)...The gaseous hydrogen.
B)... The ice.
C)...The dust grains.
D)... The uranium atoms.
E)...The gravitons.

11. How did the Solar System's shape develop?
A)...Gravity was stronger in the north/south direction.
B)...Rotation slowed collapse perpendicular to the spin axis.
C)...The black hole at the core pulled more strongly in one direction.
D)... The Moon's gravity pulled it out in one direction.
E)... A neighboring star's gravity elongated the cloud into a cigar shape.

12. Do all the planets orbit the Sun in the same direction?
A)... Yes.
B)...No.

13. Why do all the planets orbit the Sun in the same direction?
A)...Trick question. Uranus orbits the Sun opposite to the other planets.
B)...The Sun's spin exerted a gravitational force that drags them.
C)... A passing star's gravity pulled them into paths all moving in the same direction.
D)...They formed from material all circulating in the same direction in the Solar Nebula.
E)...They were flung out of the spinning Sun and retain that motion.

14. What is meant by the Solar Nebula?
A)... A cloud of hot gas in the Sun's atmosphere.
B)...The cloud surround the Sun from which comets come even today.
C)...The rotating disk of dust and gas from which the Sun and planets formed.
D)...The glow of light we see around the Sun at a total solar eclipse.
E)...None of the above.

15. Were all parts of the Solar Nebula the same temperature?
A)...Yes.
B)...No.

16. Which part of Solar Nebula was hottest?
A)...The inner part.
B)...The outer part.

17. What heated the inner part of the Solar Nebula?
A)...Friction as it spun.
B)... Heat and light from the Sun.
C)...Light from other stars focused by the Sun's gravity.
D)...TAn orbiting blackhole.
E)...None of the above.

Animation showing how compression heats a gas
Animation showing Sun heating up in Solar Nebula
18. What are planetesimals?
A)...A collection of small objects orbiting the Sun just inside Mercury's orbit.
B)... The solid chunks of material that accumulated into the planets.
C)... A swarm of solid particles in orbit perpendicular to the Earth's orbit that cause meteor showers.
D)... The objects believed by the ancient Greeks to cause sunspots.
E)...None of the above.

19. How did planetesimals form?
A)...By the accumulation and sticking of dust and solid particles in the solar nebula.
B)... By the collision of two stars. The resulting spray of debris became planetesimals.
C)...They are leftover from the formation of the Universe.
D)... From matter ejected from Jupiter's volcanoes.
E)... From matter ripped off a passing star.

20. What evidence can we see today of planetesimals?
A)...The asteroid belt.
B)... The Oort Cloud and Kuiper Belt.
C)...The many craters seen on the ancient surfaces of Solar System objects.
D)... All of the above.
E)...None of the above.

21. What is meant by accretion?
A)...The sinking of heavy material to the core of a planet.
B)... The ejection of gas from a rapidly spinning planet.
C)...The collection of material together to form a planet.
D)... The blasting apart of one planetesimal by collision with another one.
E)...The outflow of gas from the Sun sweeping the system clean of debris.

22. What had to happen to planetesimals to turn them into planets?
A)...They had to change their composition from ice to iron.
B)... They had to get hot enough to melt.
C)... They had to collect together into larger objects.
D)... Sunlight had to push them together into bigger objects.
E)...The Coriolis force had to make them spin faster.

23. What process made this occur?
A)...Magnetic forces.
B)... Sunlight pushing on them.
C)...Gravity.
D)... Collisions and sticking.
E)...both C and D.

24. Why are objects like Mercury and the moons of Saturn and Jupiter so heavily cratered?
A)...Intense volcanic activity at their birth.
B)... Intense bombardment by asteroids and planetesimals at their birth.
C)...They were bombed heavily by aliens during the first intergalactic war.
D)... Subsidence of the crust as they cooled led to "sink" holes.
E)...None of the above.


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