THE STORY OF THE UNIVERSENA
SA
The cosmic terms
you’ll need to know
to understand
the Big BangCOSMOLOGICAL
REDSHIFT
A s tretching of light , or other
electromagnetic radiation,
caused by the s tretching of
space between the galaxies as a
result of the expansion of the
Universe. This is not a Doppler
eff ec t , bec ause it does not
involve motion through space,
but is measured in units of
velocity. The cosmic
background radiation is light
from the Big Bang with a
redshift of 1,000.HUBBLE’S LAW
Actually first proposed by
Georges Lemaître, the law says
that the redshift ‘velocity’ of a
galaxy is proportional to its
distance. So a galaxy twice as
far away is receding twice as
f a s t , and so on. This does not
mean we are at the centre of
the Universe, however. The law
works the same way whichever
galaxy you observe from.MICROWAVES
Microwaves are radio waves
with wavelengths in the range
from 1-30cm. They’re used to
study the background radiation
left over from the Big Bang, and
in the study of interstellar
molecules. On Earth they’re
used in microw ave ovens , radar
and telecommunications. The
Universe is a microwave oven
with a temperature of -270.3°C.The light from Pandora’s Cluster- a group of galaxies in the
deepest realms of the observable
Universe – has been shifted to the
red end of the spectrum due to
the expansion of the Universe
another larger one had died in a
supernova, filling the cloud with gas
and dust. This debris gradually formed
a protoplanetary disc – a huge, flat
circle made up of hund reds of lumps
of rock and ice called planetesimals.
These planetesimals were the
building blocks of the Solar System.
After a few million years of crashing
and melding together, these bodies
began to resemble the planets as we
know them today.
Close to the Sun, temperatures were
too high for volatile chemicals, such
as water, to remain solid in a ny
quantity. The initial protoplanetary
disc contained only a small amount
of rocky solid material, so the four
planets that formed closest to the
Sun were comparatively small. But,
600 million kilometres from Earth,at what is now the outer edge of the
asteroid belt, temperatures were cool
enough for gases to form thick
atmospheres around rocky cores,
creating the gas giants – Jupiter,
Saturn, Uranus and Neptune.
It wasn’t just planets forming,
though; several moons did, too. Many
moons are former planetesimals
captured by a planet, but a few had a
much more violent beginning. When
the infant Earth collided with another
young planet, a huge plume of debris
was trailed behind. After a few
hundred million years, it melded
together to create the Moon.
By four billion years ago, the planets
and moons had formed, but the Solar
System still looked very different from
its current state. There were probably
many more planets than the eight 5“Planetesimals were the building blocks
of the Solar System. After a few million
years of crashing together, these bodies
began to resemble the planets”
NEED TO KNOW