C25SunandtheUniverse

Which row shows the most common elements in the Sun and the regions of the electromagnetic spectrum in which most of the Sun's energy is radiated?

• A

• B

• C

• D

What is the meaning of a light-year?

• the distance light travels in space in one year

• the number of years it takes light to travel from the Sun to the Earth

• the speed that light travels in space

• the time it takes light to travel from the Sun to the nearest star

What is the approximate diameter of the Milky Way?

• 100 light-years

• 1000 light-years

• 10000 light-years

• 100000 light-years

Nuclear reactions is the Sun release large quantities of energy.

Which statement about this process is correct?

• It involves the fission of helium to produce hydrogen

• It involves the fission of hydrogen to produce helium

• It involves the fusion of helium to produce hydrogen

• It involves the fusion of hydrogen to produce helium

The Sun radiates most of its energy in three regions of the electromagnetic spectrum. In the pie chart, region 1 is infrared radiation and region 2 is visible radiation.

What is region 3?

• microwave

• radio

• ultraviolet

• X-ray

What are the three main types of radiation emitted by the Sun?

• infrared, radio waves and ultraviolet

• infrared, visible light and ultraviolet

• microwaves, visible light and X-rays

• radio waves, X-rays and ultraviolet

What is a light-year?

• the time for light to travel 1 km in space

• the time for light to travel from the Sun to the Earth

• the distance travelled in space by light in one year

• the distance travelled by light from the Sun to the Earth

What is the main process that powers the Sun?

• burning of helium and oxygen

• burning of hydrogen and oxygen

• nuclear fusion of hydrogen to form helium

• nuclear fission of helium to form hydrogen

A galaxy is 3.0 x 10²⁰ km from the Earth.

At which speed is the galaxy moving away from the Earth?

• 660 km/s

• 6600 km/s

• 660 m/s

• 6600 m/s

An astronomer observes a distant galaxy.

The table shows how the distance and the speed of recession of the galaxy are determined.

Which row is correct?

• A

• B

• C

• D