Planets in the Solar System - Lecture Notes Review

A set of practice questions in Q&A format covering key facts about the planets, their properties, and related concepts from the notes.

What is the closest planet to the Sun?

Mercury (approximately 57.9 million kilometres away).

Which planet is the smallest in the solar system?

Mercury.

Mercury’s diameter is smaller than Earth’s by what percentage?

40% smaller.

Why does Mercury’s sky appear dark in outer space?

Because Mercury lacks an atmosphere to scatter light.

Which is the largest planet in the solar system?

Jupiter.

How much more massive is Jupiter than Earth?

Almost 320 times the mass of Earth.

Why is Jupiter considered the protector of the Earth?

Its strong gravity deflects large objects away from Earth.

Which planet is known as the greenhouse planet due to CO2?”

Venus.

Which direction does Venus rotate, and what is the sunrise effect?

Venus rotates from east to west, so the Sun rises from the West.

What is the approximate surface temperature of Venus?

Approximately 460°C.

Which planet has a prominent ring system?

Saturn.

How many moons have been found orbiting Saturn?

62.

Which is Saturn’s biggest moon (among its moons)?”

Titan (noting that Ganymede is larger than Titan).

What is Earth’s position from the Sun and its uniqueness?

Third planet from the Sun; the only planet known to harbor life.

What percentage of Earth’s surface is covered by water?

More than 71%.

What does Earth’s atmosphere do for the planet?

Protects the surface from solar wind, harmful UV rays, and radiation.

What is Uranus known for regarding its axis?

Its axis is tilted almost parallel to its orbit; it rotates on its side.

How long does Uranus take to orbit the Sun?

84 years.

What is Mars commonly called and what are its two moons?

The Red Planet; Phobos and Deimos.

How are planets like Jupiter, Saturn, Uranus, and Neptune classified?

As 'giant gas' planets.

What is an astronomical unit (AU) and what is 1 AU in kilometers?

The average distance from the Sun to a planet; 1 AU ≈ 1.5 x 10^8 km.

What is a light year and its approximate distance in kilometers?

Distance light travels in one year; about 9.5 x 10^12 km.

How does distance from the Sun affect a planet’s orbital time?

The further a planet is from the Sun, the longer it takes to orbit (e.g., Mercury ~88 days, Neptune ~164.8 years).