Red shift and the Big Bang: Space physics: Physics: GCSE (9:1)

Electromagnetic spectrum

A continuous spectrum containing all different types of electromagnetic radiation

Emission spectrum

A spectrum containing dark lines when the elements in a star absorb certain frequencies of light

What an emission spectrum tells us

Different elements absorb different frequencies of light to produce a unique pattern of dark lines on the spectrum

Galaxy

A cluster of billions of stars that is held together by gravity.

Emission spectra from different galaxies

The dark lines in the spectra from distant galaxies are further along the spectrum and show an increase in wavelength

Red shift

When the lines on an emission spectrum are moved or shifted towards the red end of the spectrum

What red shift tells us

The space between the Earth and distant galaxies is expanding

Relationship between amount of red shift and speed of galaxies

The more the light from a distant galaxy is red-shifted, the faster the galaxy is moving away from Earth

How red shift lead to the development of the Big Bang theory

Generally, the further away a galaxy is, the more its light is red-shifted which suggests that the Universe is, and has been, expanding since it was created

Big Bang Theory

The scientific theory that is used to describe the early stages of the Universe

When the Big Bang occurred

13.8 billion years ago

What happened during the Big Bang

There was a huge explosion which started the formation and expansion of the Universe from an extremely small, hot and dense region of matter

CMBR (Cosmic Microwave Background Radiation)

The remains of the heat energy released from the Big Bang which is now spread thinly across the whole Universe

How CMBR provides evidence for the Big Bang theory

Astronomers have discovered microwave radiation from all directions in space which is at a temperature of about –270 ºC

Dark energy

An unknown form of energy that could explain why the expansion of the Universe is accelerating

Dark matter

An unseen form of matter that could explain why galaxies rotate faster than their visible mass should allow