life in the universe… since the late 1960’s, scientists have seriously begun to look for life on...

LIFEIn the Universe…

Since the late 1960’s, scientists have seriously begun to look for life on other planets apart from the Earth.

These efforts have fallen into 4 main areas:

Scientists study

meteorite samples

that have landed

on Earth. Some of

them originally came

from other planets, such as Mars.

They may contain the chemical traces for life, or even fossil traces of bacteria.

(1) Analysis of meteorites

In 1996, NASA announced that these were fossilized Martian bacteria, found on a meteorite that hit Earth from Mars over 15 million years ago.

(1) Analysis of meteorites

NASA was forced to admit that it could be evidence of an unknown Earth bacteria from a few million years ago!

We have already sent space-probes to most planets in our solar system. Although there has been no life discovered, there are encouraging signs:

(2) Sending probes to planets

• Mars once had water flowing on it

• Many planets have atmospheres

• Some of Jupiter & Saturn’s moons (e.g., Titan) may have warm, liquid seas under their ice covered surfaces.

The Viking probe was sent to Mars to look for life in the late 1970’s, but found none. It sampled the soil to look for bacterial life.

(2) Sending probes to planets

Large radio telescopes, such as the one at Arecibo in Puerto Rico, detect faint radio signals from outer space.

(3) Listening to signals from space

Project SETI (The Search for Extra-Terrestrial Intelligence) has found a few possible signs of a signal:

(3) Listening to signals from space

There was a brief attempt to send signals into space, but the USA quickly stopped this (when Independence Day became a hit!!!).

In the 1990’s, Astronomers were able to start looking for planets around nearby stars.

(4) Looking for Extra-Solar Planets

Large planets can cause starts to ‘wobble’ due to the gravitational pull between them.

Currently, over 100 planets have been discovered in this way, and it now seems that most stars may have their own system of planets.

(4) Looking for Extra-Solar Planets

With more sophisticated telescopes and satellites, astronomers can search for smaller planets around stars that are further away.

CONDITIONS FOR LIFE

We think that for life to develop on another planet it would need:

• LIQUID WATER

• A SUITABLE TEMPERATURE

• A SUITABLE PRESSURE

• A SUITABLE ATMOSPHERE

LOTS OF PLANETS?

In the universe, there are:

• Billions of Galaxies ....

• ...each containing 100 billion stars..

•...each star having several planets

If only 1 in a billion planets developed life, that still means a vast number of possible alien civilisations...

EARTHLINGS…

We have come to conduct unpleasant experiments on you & your bovine life-forms, and mess up your agricultural produce sites with unusual circular

shapes…

..HA..HA..HA…