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LIFE
In 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:
(1) Analysis of meteorites
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.
NASA was forced to admit
that it could be evidence
of an unknown Earth
bacteria from a few million
years ago!
(2) Sending probes to planets
We have already sent space-probes to most planets in
our solar system. Although there has been no life
discovered, there are encouraging signs:
• 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.
(2) Sending probes to planets
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.
(3) Listening to signals from space
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:
There was a brief attempt to
send signals into space, but
the USA quickly stopped this
(when Independence Day
became a hit!!!).
(4) Looking for Extra-Solar Planets
In the 1990’s, Astronomers were able to start looking
for planets around nearby stars.
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…