What percentage of the solar system's total mass is contained within the Sun?

• 50%

• 75%

• 98%

• 100%

Which ancient Greek astronomer proposed a sun-centered model of the universe, but was largely ignored?

• Ptolemy

• Aristotle

• Aristarchus of Samos

• Eratosthenes

What significant discovery did Johannes Kepler make about planetary orbits?

• Planets are flat

• Planets move in perfect circles

• Planets move in elliptical paths

• Planets do not orbit the Sun

How much wider is Jupiter compared to Earth?

• 5 times

• 8 times

• 11 times

• 15 times

What is a key difference between the inner planets (Mercury, Venus, Earth, Mars) and the outer planets (Jupiter, Saturn, Uranus, Neptune)?

• Inner planets are larger and gaseous

• Outer planets are smaller and rocky

• Inner planets are rocky and smaller

• Outer planets have no atmospheres

What is the Oort Cloud?

• A spherical cloud of icy objects far beyond the planets.

• A flat disk of rocky asteroids between Mars and Jupiter.

• A region of hot gas surrounding the Sun.

• A collection of dust and debris orbiting within the inner solar system.

What event is believed to have initiated the collapse of the cloud of gas and dust that formed our solar system?

• A sudden increase in the cloud's internal heat.

• The gravitational pull of a passing black hole.

• A shockwave from an exploding star or a passing cloud.

• A spontaneous decrease in the cloud's angular momentum.

As the initial cloud of gas and dust collapsed, it began to spin faster and flatten into a disk. What physical principle explains this phenomenon?

• Conservation of energy.

• Newton's Third Law of Motion.

• Conservation of angular momentum.

• The Doppler effect.

What term describes the small, growing clumps of dust and other matter that eventually combined to form planets?

• Protoplanets

• Asteroids

• Planetesimals

• Comets

What was the primary reason that planets closer to the Sun became rocky, while those farther away became gas giants?

• The inner planets had stronger magnetic fields.

• The outer regions of the disk contained more heavy elements.

• The inner regions were too hot for light gases to condense and be retained by smaller planets.

• The Sun's radiation pushed all the rocky material to the outer solar system.