Phobos and Deimos: Moons of Mars

Mars has two small moons, Phobos and Deimos, believed to be captured asteroids. Discovered by Asaph Hall in 1877, they are named after Greek mythological figures. Phobos orbits Mars closely, while Deimos is more distant. Both moons are small, cratered, and resemble asteroids. Phobos is slowly spiraling towards Mars and may eventually break apart, forming a ring around the planet.

Who discovered the moons of Mars, Phobos and Deimos?

• Nicolaus Copernicus

• Asaph Hall

• Isaac Newton

• Galileo Galilei

What are Phobos and Deimos thought to be?

• Comets

• Captured asteroids

• Artificial satellites

• Fragments of Mars

How does Phobos compare in size to Earth's moon?

• Twice the size

• One-third the size

• Same size

• Larger

What is the orbital period of Deimos around Mars?

• 30.35 hours

• 24 hours

• 12 hours

• 4 hours

What is the mass of Phobos compared to Deimos?

• They have the same mass

• Deimos is heavier

• Phobos is heavier

• Mass is unknown

What is the largest crater on Phobos called?

• Copernicus

• Aristarchus

• Tycho

• Stickney

What material are Phobos and Deimos primarily composed of?

• Silicon and oxygen

• Ice and carbon-rich rock

• Iron and nickel

• Hydrogen and helium

What is the fate of Phobos as it continues to orbit Mars?

• It will remain in stable orbit

• It will collide with Mars

• It will escape Mars' gravity

• It will form a ring around Mars

How long is Phobos expected to remain in orbit around Mars before breaking apart?

• 500 million to 1 billion years

• 100 to 200 million years

• 10 to 50 million years

• 1 to 5 million years

What is the primary reason Phobos is spiraling inward towards Mars?

• Tidal forces

• Phobos' high speed

• Solar winds

• Mars' gravitational pull