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 waves B. To collect samples – and the craft must return to earth C. 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 for 1. 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 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 this will drill into the ice-cap.

Life outside the solar system

Distances and times Mars km 2 or years by spacecraft Nearest star other than sun years by spacecraft 4 years at the speed of light

SETI The Search for Extra Terrestial Intelligence

The Drake equation There are alien races in the milky way galaxy Based upon large assumptions

Listening for signals 1. Microwaves are short radio waves 2. They can pass through the gas and dust clouds in space 3. They can be collected by radio telescopes 4. 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

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