What primary mechanism drives the initial formation of stars and planets?

• Electromagnetic radiation
• Gravitational collapse
• Thermal expansion
• Magnetic field interactions

In the early solar system formation, what caused the interstellar cloud to become flattened?

• Solar wind
• Centripetal force
• Magnetic fields
• Cosmic radiation

Why did inner planets form as rocky and dense bodies?

• They were closer to the Sun
• They contained elements that resist vaporization
• They had more gravitational pull
• They cooled faster

Which planet was the first large planet to develop in the solar system?

• Saturn
• Mars
• Jupiter
• Neptune

What is an astronomical unit (AU) defined as?

• Distance between Mars and Jupiter
• Earth's diameter
• Earth's average distance from the Sun
• Diameter of the solar system

Who first suggested a heliocentric model of the solar system?

• Galileo Galilei
• Isaac Newton
• Nicolaus Copernicus
• Johannes Kepler

What mathematical relationship describes planetary orbital periods in Kepler's Third Law?

• P² = a³
• P = a²
• a = P³
• P² = 2a

What is retrograde motion?

• Planets moving faster than light
• Apparent backward movement of a planet
• Planets reversing orbit
• Solar system rotation

What are planetesimals?

• Tiny planets
• Space debris
• Solid particle objects that can form planets
• Asteroid fragments

What defines the eccentricity of an elliptical orbit?

• Total orbit length
• Distance between foci
• Planetary mass
• Orbital speed