Exploring the Universe

Modern telescopes:•Image is magnified•Star formations can be seen with EM waves other that visible light•Attached to computers – longer exposure = clearer pictures

Space probes and landers:• Space probes look for water and minerals•Landers analyse soil samples and bacteria, they have been to Mars, the Moon, one of Jupiter's moons and Mercury

Human spaceflight:• Humans are sent into space

Theories of the Universe

• Steady State Theory: The Universe has no beginning or end, it is expanding and new matter is being created as it expands.

• Big Bang Theory: The Universe started about 14 billion years ago in a huge explosion called the Big Bang. Since then the universe has been expanding and changing and may have an end depending on its density.

Whats the evidence?

The picture above shows the EM spectrum. Right in the middle we have visible light, which is what stars produce.

So what would happen to the light from a star if it was coming towards you?

Red Shift

Stars produce mainly yellow light. If a star was to move away from us, the wavelength of the light would increase.

This would make the light appear red!

Red Shift

Stars produce mainly yellow light. If a star was to move towards us, the wavelength of the light would decrease.

This would make the light appear blue!

LO: Understand what is meant by the Doppler Effect and how it affects light

Red ShiftLO: Understand what is meant by the Doppler Effect and how it affects light

http://www.youtube.com/watch?v=FhfnqboacV0

Doppler Effect• The Doppler effect can be used to

explain red shift.• As an emergency vehicle’s siren

passes you, its pitch gets lower. This is known as the Doppler effect.

• http://www.youtube.com/watch?v=h4OnBYrbCjY

Doppler Effect• What two things does pitch depend

on?

• Pitch depends on the Wavelength and frequency of the sound wave.

Doppler Effect• The sound waves behind a moving sound

source become ‘stretched’, making the frequency lower and the wavelength longer and so the sound becomes lower in pitch.

• The opposite happens in front of a sound source.

Doppler Effect

• This is the evidence for both theories, as they both state the universe is expanding. But what is the evidence for only the big bang?

The observation of red shift is a key piece of evidence for the Big Bang theory about the origin of the Universe.

The other key piece of evidence for the Big Bang theory is cosmic microwave background radiation (CMB).

This states that the Universe ‘began’ with a colossal explosion 13,700 million years ago and has been expanding ever since.

CMB is radiation remaining from the Big Bang explosion and fills the whole of the Universe.

This radiation has cooled as the Universe has expanded andis now slightly less than 3 degrees above absolute zero.

To know the Big Bang Theory and it’s evidence.