Astronomy Test 5

What is Jupiter's mass?

1.9 × 10²⁷ kg, twice as much as all other planets combined.

What is Jupiter's radius?

71,500 km (11.2× Earth's radius).

What is Jupiter's density and what does it imply?

1300 kg/m³, meaning it cannot be rocky or metallic.

What is Jupiter's rotation period?

9 hr 55 min.

What are the layers of Jupiter's interior?

Molecular hydrogen outer layer, metallic hydrogen middle layer, rocky/icy core.

Why does Jupiter radiate more energy than it receives?

It is still cooling from gravitational compression (leftover heat of formation).

Why isn't Jupiter a star?

It would need 80× more mass to initiate fusion.

What are Jupiter's belts and zones?

Zones are bright, cooler, higher; belts are darker, warmer, lower.

What is Jupiter's atmospheric composition?

Hydrogen, helium, methane, ammonia, water vapor.

What causes Jupiter's fast winds?

Internal heat, not sunlight.

What is the Great Red Spot?

A storm at least 300 years old.

What causes Io's extreme volcanism?

Tidal forces from Jupiter and Europa.

What is unique about Io?

It is the most geologically active object in the solar system.

What is Europa's surface like?

Smooth icy surface with cracks and likely a subsurface ocean.

What is notable about Ganymede?

Largest moon in the solar system; mix of rock and ice.

What is notable about Callisto?

Heavily cratered; no evidence of plate activity.

What is Saturn's density?

700 kg/m³ — less than water.

What causes Saturn's flattened shape?

Rapid differential rotation.

What is special about Saturn's rings?

They are wide but extremely thin.

What are Saturn's interior layers?

Molecular hydrogen layer, metallic hydrogen layer, icy/rocky core.

Why does Saturn radiate extra energy?

Helium droplets form and fall ("helium rain"), releasing heat.

How does Saturn's atmosphere compare to Jupiter's?

Similar bands and zones but with more muted colors.

How many cloud layers does Saturn have?

Three, thicker than Jupiter's; only the top is visible.

Does Saturn have storms?

Yes, but fewer and shorter-lived; occasional huge ones.

Which planet has stronger coloration in its atmosphere?

Jupiter.

Which planet has faster winds?

Saturn.

Which planet has thicker cloud layers?

Saturn.

What is the energy source for Jupiter vs Saturn?

Jupiter: cooling from formation; Saturn: helium rain.

What is Titan's atmosphere like?

Thick, denser than Earth's, composed mostly of nitrogen and argon.

What hides Titan's surface?

A thick orange haze.

What revealed Titan's surface?

The Huygens lander.

What gives Uranus and Neptune their blue color?

Methane in the atmosphere absorbs red light.

What is unusual about Uranus's tilt?

Axis is tilted 98°, almost lying in its orbital plane, causing extreme seasons.

How does Neptune's appearance differ from Uranus?

Neptune has visible bands and had a 'Dark Spot' storm.

How do Uranus and Neptune differ internally from Jupiter and Saturn?

They lack a metallic hydrogen layer; instead have a 'slushy' ice layer.

What are their magnetic fields like?

Strong, tilted, and off-center — not produced by typical dynamos.

What does Triton's retrograde orbit indicate?

It was captured, not formed with Neptune.

What surface activity is seen on Triton?

Nitrogen geysers and possible ice volcanoes.

Describe Uranus's rings.

Narrow, dark, maintained by shepherd moons.

Describe Neptune's rings.

Five rings—three narrow, two wide—with clumpy structure.

How do these compare to Saturn's rings?

Saturn's rings are brighter, wider, more complex, and icy.

Where do most asteroids orbit?

Between Mars and Jupiter in the asteroid belt.

What are the main asteroid types?

C-type (carbon), S-type (silicate), M-type (metallic).

What are Apollo asteroids?

Asteroids whose orbits cross Earth's orbit.

What are Trojan asteroids?

Asteroids at Jupiter's L4 and L5 Lagrange points.

What are the main parts of a comet?

Nucleus, coma, hydrogen envelope, dust tail, ion tail.

How do comet tails behave?

Always point away from the Sun.

What type of orbit do comets have?

Highly eccentric.

Where do most comets come from?

Kuiper Belt (short period) and Oort Cloud (long period).

What is the Kuiper Belt?

Region beyond Neptune containing icy bodies (KBOs).

Why is Pluto a dwarf planet?

Orbits the Sun ✔, Is spherical ✔, Has NOT cleared its orbit ✘.

What is a meteoroid?

A small rocky/icy object in space, <100 m wide.

What is a meteor?

The streak of light when a meteoroid burns in the atmosphere.

What is a meteorite?

A meteoroid that reaches Earth's surface.

What causes annual meteor showers?

Earth passing through a comet's debris trail.