P3 Revision Notes:Space

Just some notes on Space


HideShow resource information
  • Created by: Lauren
  • Created on: 26-03-12 16:40
Preview of P3 Revision Notes:Space

First 429 words of the document:

Introduction to Galaxies
Around 13 billion years ago, the Universe was created by the Big Bang. The Big Bang created
space, radiation and time, and at first, our Universe was just a hot glowing ball of radiation and
matter ­ but as it expanded, its temperature fell and it is now cold and dark, except for certain hot
spots we call stars. The stars we can see at night are all in our Milky Way galaxy (our home
galaxy). The Sun is just one of billions of stars in the Milky Way galaxy, which we can see, along
with others using a telescope ­ as well as certain other individual stars in other galaxies. We know
that there are billions of different galaxies, all with empty space in between them. Light has taken
billions of years to finally reach us from distant galaxies.
The photograph here on the left shows Andromeda, the nearest large galaxy to the Milky Way
galaxy. The photograph on the right is a Protostar.
The Universe became transparent as it expanded, and radiation passed through the empty space
between its atoms. This is the stage at which background microwave radiation was created ­ we
call this the Dark Age of the Universe. Over a few billion years, the Universe was just a dark empty
space of hydrogen and helium ­ but then stars and galaxies formed, lighting up the Universe.
Gravity in the Universe
Although uncharged atoms don't repel each other ­ they can attract each other. During the Dark Age,
the force of gravitational attraction was at work without any opposition from repulsive forces. As
the Universe expanded, denser parts became more common, and gravity pulled more and more
matter into the denser parts ­ forming larger clumps of space matter. Eventually, the force of gravity
turned the clumps into stars and galaxies. A few billion years after the Big Bang, the Dark Age ended
­ stars had lit up the Universe.
Star Birth, Life and Death
A star forms from a cloud of gas and dust. This matter joins together using its own gravitational force
­ and as the clouds merge together, it becomes denser and denser ­ until it is a protostar (a star in
the making). A protostar becomes denser and gets hotter until the point where it becomes hot
enough for the hydrogen nuclei (and nuclei of other light elements) to fuse together. Energy is

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

released in this process, causing the core to get hotter, bigger and brighter and eventually it begins to
shine ­ a star has been born.
Due to hydrogen fusion in the core, stars (including the Sun) radiate energy. This is the main part of
a star's life, as it can continue to do it for billions of years until it runs out of hydrogen nuclei to fuse
together.…read more

Page 3

Preview of page 3

Page 4

Preview of page 4

Here's a taster:

Heavy elements only form when the big stars collapse and explode as supernova. This happens
because the immense pressure of the collapsing causes smaller nuclei to fuse into larger nuclei ­ but
this time larger than iron. The explosion scatters the star into space, and the debris from the
supernova contains every known element ­ from the small, light ones, to the heaviest ones.
Eventually a new star will form when gravity brings the debris closer together.…read more


No comments have yet been made

Similar Physics resources:

See all Physics resources »See all resources »