Cosmology

Describe The Doppler Effect

The change in frequency of a wave when the observer moves towards or away from the source.

Define a standard candle

An object of known absolute magnitude

How can we estimate the age of the universe?

1/Hubble’s constant

How do we know the universe is expanding?

Redshift of distant galaxies

How does CMBR provide evidence of the big bang?

The short wavelengths of gamma radiation have become stretched into longer wavelength microwaves.

How does the abundance of light elements provide evidence of the big bang?

They were produced in the first few moments of the big bang.

What is a quasar?

Active galactic nucleus

Describe the formation of a quasar

Material is pulled towards a supermassive black hole at the centre of a galaxy and swirls around in an accretion disc. Friction in the disc produces massive amounts of electromagnetic radiation which leaves as two jets.

What is an exoplanet?

A planet that orbits a star other than the sun.

How can we observe exoplanets indirectly?

Variation in Doppler shift and transit method

Describe the Doppler shift method

The star is influenced by the gravity of the planet causing it to wobble and create a variation in its redshift.

Describe the transit method

As the planet passes in front of the star, we can measure a variation in the brightness.