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Stars
> The formation of a star occurs when a hydrogen cloud called a nebula contracts and heats up this leads to a formation of a protostar this heats up even more triggering nuclear fusion to begin, after this a main sequence star has been formed

> the star will eventually run out of hydrogen this means the star swells the thousands times it size forming a red giant, for a medium siz d star the red giant will drift off to form a new planters nebula however for a big star it will explode and form a supernova, the core is squashed and is made into a neutron star. Supermassive stars also go supernovae the core that remains collapses and forms a black hole which has so much gravity light can't even escape it.

The universe

The universe began with the Big Bang we have 2 pieces evidence of this-
-we can detect cosmic background radiation which was created during the Big Bang
-the universe is still expanding this means at one point the universe must have been squashed into a infinitesimally small space

We know the universe is expanding due to redshift
All stars and galaxies have a spectrum of light that shows what chemicals they are made from, when comparing light spectrums to different galaxies we notice they are shifted toward the red end of the spectrum this is because the galaxies are moving away from us
The further away the Galaxy is the more red shifted it is, the faster it's moving away.

Nuclear radiation
Alpha - smoke detectors, absorbed by paper,
Beta- tracers and paper thickness gauges, absorbed by 3mm of alliminum
Gamma- non destructive testing,treating cancers , tracers, absorbed by thick piece of lead.

These types of radiation…

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