IGCSE Review - Astrophysics

Mars has a smaller gravitational field strength at the surface than the Earth. This is because...

• The mass of Mars is smaller than Earth.

• Mars has a very thin atmosphere.

• Mars has no water on the surface.

• Mars orbits the Sun at a slower speed than Earth.

Which of the following answers best describes the orbits of planets, moons and comets?

• A

• B

• C

• D

Which of the following gives the sizes of astronomical objects in order of increasing size?

• Solar system, universe, galaxy

• Universe, galaxy, solar system

• Solar system, galaxy, universe

• Galaxy, solar system, universe

Approximately how many stars are in a typical galaxy?

• Hundreds of stars

• Thousands of stars

• Millions of stars

• Billions of stars

What is the name of our own galaxy containing the Sun?

• The Andromeda galaxy

• The Milky Way galaxy

• The Orion galaxy

• The Hubble galaxy

Which of these statements is correct?

• Planets orbit moons, planets orbit stars

• Moons orbit planets, stars orbit planets

• Moons orbit stars, stars orbit planets

• Moons orbit planets, planets orbit stars

The formula above can be used to calculate the orbital velocity v of any object. It can be re-arranged to find the radius of the orbit.

Which of the following has been correctly re-arranged?

• 
• 
• 
• 

The radius of the Earth's orbit is about 150 million kilometres. In standard form, and given in metres, this is...

• 1.5 x 10⁸ m

• 1.5 x 10¹⁰ m

• 1.5 x 10¹¹ m

• 1.5 x 10¹² m

The Earth orbits the Sun in 1 year, which is 3.2 x 10⁷ seconds. The radius of the Earth's orbit is about 150 million kilometres. What is the orbital velocity of the Earth?

• 4.6 x 10³ m/s

• 29 m/s

• 4.6 m/s

• 2.9 x 10⁴ m/s

Astronomers make detailed observations of individual stars. Which measurement will lead to finding the surface temperature of the star?

• The colour of the star.

• The brightness of the star.

• The observed size of the star.

• The motion of the star.