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Space GapFill
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4-5
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Stars are formed in huge clouds of gas and dust called
. These clouds are much denser than the vast majority of space, but are still much less dense than even the best vacuums ever created on Earth! Over time, these clouds can come together via
to create large masses such as asteroids, planets, moons and stars. If large enough, these large masses can become stars - but they are only protostars until the pressures and temperatures at their centres become high enough for the stars to start releasing energy via
. Once a star begins shining, it is considered a
, where it spends most of its lifetime - our Sun is in this stage of its life cycle.
The next stage in a star's life cycle depends on the star's . Some, like our Sun, will become red giants, where they expand massively - when our Sun becomes a red giant billions of years in the future, it will become large enough to swallow Earth. Eventually these red giants shed their outer layers, leaving behind their hot core, known as a - eventually these will cool down and stop glowing, but they are so hot that this takes longer than the current age of the universe, so no cooled-down cores like this yet exist!
Other stars become red supergiants, which are significantly larger than red giants. When these run out of all fuel, they collapse and then explode in what are known as - these are the brightest objects in the universe, and the source of all the elements with throughout the universe. The objects left over can be either , which are so dense that protons and electrons are forced together in their cores, or , which have such high gravity that nothing can escape them - not even light.
All of the objects in our solar system - suns, planets, moons and artificial satellites - move around each other in patterns known as , which are dictated by .
As scientists' understanding of the universe grew, they noticed something strange - stars and galaxies that were further away had wavelengths that were longer than expected, an effect known as . This implies that all of the galaxies are moving away from each other, and were once much closer together; called the theory. But there is still a lot for scientists to understand; many scientists believe we can only see around 5 % of all the mass and energy in the universe, with the rest being mass and energy.
The next stage in a star's life cycle depends on the star's . Some, like our Sun, will become red giants, where they expand massively - when our Sun becomes a red giant billions of years in the future, it will become large enough to swallow Earth. Eventually these red giants shed their outer layers, leaving behind their hot core, known as a - eventually these will cool down and stop glowing, but they are so hot that this takes longer than the current age of the universe, so no cooled-down cores like this yet exist!
Other stars become red supergiants, which are significantly larger than red giants. When these run out of all fuel, they collapse and then explode in what are known as - these are the brightest objects in the universe, and the source of all the elements with throughout the universe. The objects left over can be either , which are so dense that protons and electrons are forced together in their cores, or , which have such high gravity that nothing can escape them - not even light.
All of the objects in our solar system - suns, planets, moons and artificial satellites - move around each other in patterns known as , which are dictated by .
As scientists' understanding of the universe grew, they noticed something strange - stars and galaxies that were further away had wavelengths that were longer than expected, an effect known as . This implies that all of the galaxies are moving away from each other, and were once much closer together; called the theory. But there is still a lot for scientists to understand; many scientists believe we can only see around 5 % of all the mass and energy in the universe, with the rest being mass and energy.