Life in the universe

The questions are

Is there life elsewhere in our solar system?

Is there life outside our solar system?

Ingredients for life

1. Liquid water

2. Atoms of C, O, H, N

3. Energy

The earth contains these ingredients

Recipe for life

1. The seas of the early earth – often called the primordial soup contain the atoms

2. The Energy may come from lightning, hot underwater springs and the sun

Basic life

1. Amino acids form

2. These join to make proteins and DNA

3. DNA can reproduce itself

4. Bacteria form

Life?

Life in our solar system?

Definite locations

The earth

Possible locations

Mars

Europa

Collecting evidence

Send a spacecraft A. To take pictures of the surface –

transmit back using radio wavesB. To collect samples – and the craft

must return to earthC. To examine the samples of

atmosphere – can be done and results sent back using radio waves

Only realistic in our solar system

What to look for1. Photos of organisms alive or dead or

their effects

2. Fossils in rocks – including fossilised bacteria

3. What the atmosphere is composed of

4. Changes to the atmosphere in a closed box

Atmospheric changes in a closed box- 1

Samples of moon rock

atmosphere

Atmospheric changes -2

1. If the amount of O goes up

2. If the amount of CO2 goes down

3. Then there is probably simple life in the rocks

Martian meteorites

1. A lump of rock from space that landed on earth was believed to be from Mars.

2. It was examined

Life on mars?

1. Fossilised bacteria were found in the rock

2. These bacteria were smaller than any found on earth

Some experts

are not convinced!

Life on Europa?

1. Surface temperature –170C – too cold for life

2. Europa is covered with ice but it may be liquid beneath the surface. OK for life.

3. A robot probe will be sent by NASA in 2008 - this will drill into the ice-cap.

Life outside the solar system

Distances and times

Mars 100 000 000 km 2 or years by spacecraft

Nearest star other than sun 200 000 years by spacecraft 4 years at the speed of light

SETI

The Search for

Extra Terrestial

Intelligence

The Drake equation

There are 10 000 alien races in the milky way galaxy

Based upon large assumptions

‘Listening’ for signals

1. Microwaves are short radio waves2. They can pass through the gas and

dust clouds in space3. They can be collected by radio

telescopes4. Hundreds of amateurs have dishes

connected to PCs these collect and display microwave signals

Signals from space - 1

Regular

Actually emitted by a pulsar – a rotating star

Signals from space - 1

Irregular

314 sent out by eti

Read P212/213