The Sun
What process powers the Sun?
Nuclear fusion
Name the four terrestrial (rocky) planets.
Mercury, Venus, Earth, and Mars.
What force drives all planetary motion?
Gravity.
What shape are planetary orbits, according to Kepler’s 1st Law?
Elliptical.
How far is Earth from the Sun in AU?
1 AU (about 93 million miles).
What is the hottest part of the Sun?
Core
Name the four gas giants.
Jupiter, Saturn, Uranus, and Neptune.
How long does Earth take to rotate once on its axis?
24 hours.
What does orbital eccentricity measure?
How stretched out an orbit is (0 = circle, near 1 = elongated ellipse).
What is the “Goldilocks Zone”?
The habitable zone where conditions are just right for liquid water.
Which layer of the Sun is visible only during a solar eclipse?
Corona
Why are the inner planets denser than the outer planets?
They formed closer to the Sun with heavier, rockier materials.
What is Earth’s axial tilt, and why is it important?
23.5° — it causes seasons.
State Kepler’s 2nd Law.
Planets sweep out equal areas in equal times.
Name one way Earth’s atmosphere supports life.
Provides oxygen, blocks UV radiation, or traps heat with the greenhouse effect.
Why do sunspots appear darker than the rest of the Sun’s surface?
They are cooler areas caused by strong magnetic fields.
What is perihelion?
The point where a planet is closest to the Sun and moves fastest.
State Kepler’s 1st Law.
Planets orbit the Sun in ellipses with the Sun at one focus.
State Kepler’s 3rd Law.
The farther a planet is from the Sun, the longer its orbital period.
What generates Earth’s magnetic field?
Motion of liquid iron in the outer core.
What can solar flares and CMEs cause on Earth?
Auroras, satellite disruption, and power outages.
How is a comet’s orbit different from a planet’s orbit?
It is highly elliptical and irregular compared to nearly circular planetary orbits.
According to Kepler’s 2nd Law, how does a planet move at perihelion vs. aphelion?
Faster at perihelion (closer to Sun), slower at aphelion (farther from Sun).
How does Kepler’s 3rd Law explain why Neptune takes longer to orbit than Earth?
Neptune is farther from the Sun, so it moves slower and has a longer orbital period.
Why is Earth unique compared to other planets in the solar system?
It has abundant liquid water and the right conditions for life.