Astronomy and Cosmology A Level

Light Year

• distance from Earth to Sun-used to measure distances within our solar system (ex. distance between Mars and Jupiter)

• distance light travels in one year-used to measure distances outside our solar system (ex. measuring distances between stars/galaxies)

• Theory of early astronomers. Earth is at the center of the universe. The sun and planets would revolve around the Earth.

• Sun is at the center of the solar system.

Sirius and Canopus are the 2nd and the 3rd brightest stars after the Sun.

Canopus has a much greater luminosity than Sirius but is it is dimmer than Sirius. This is because Canopus is much ___________.

Sirius and Canopus are the 2nd and the 3rd brightest stars after the Sun.

Canopus has a much greater luminosity than Sirius but is it is dimmer than Sirius. This is because Canopus is much ___________.

Which of the following is the correct relationship for Wein's displacement law?

The peak of the distribution of wavelength of the electromagnetic radiation emitted by the Sun is in the region of ________.

• infrared

• X-rays

• visible light

• microwave

What phenomenon leads to the idea that the Universe is expanding?

• redshift

• greenshift

• blueshift

• purpleshift

Light from almost all galaxies are red-shifted. This means that the galaxies _____ .

• are not moving

• are moving away from us

• are moving towards us

• are moving around us.

One absorption line observed from a distant star has a wavelength of 722 nm. This line has a wavelength of 705 nm in the lab. What is the speed of the star?

Hubble's law states that ......

• the recession speed of a galaxy is not related to the its distance from the Earth

• the recession speed of a galaxy is directly proportional to its distance from the Earth

• the recession speed of a galaxy is inversely proportional to its distance from the Earth

• the recession speed of a galaxy is inversely proportional to the square of its distance from the Earth

Which of the following statements is true according to the Big Bang theory? (Select all.)

• The universe started from a single point.

• Galaxies are moving away from each other because of the expansion of

• The universe will continue to expand in size forever.

• The early universe is much smaller and hotter.