PARADE OF PLANETS - Galaxy by marnah on DeviantArt (original) (raw)

The history of the study of planets and stars is measured in millennia, the Sun, comets, asteroids and meteorites – in centuries. But galaxies, clusters of stars, cosmic gas and dust particles scattered throughout the universe, have become the object of scientific research only recently. Galaxies were born shortly after the stars. It is believed that the first luminaries broke out no later than 150 million years after the Big Bang.

The galaxy consists of stars of different types and star clusters, gas and dust nebulae, dark matter - this is the part of the universe that does not emit light.

The ratio of these parts is different, depending on the shape and type of the galaxy. In some cases, dark matter can make up the bulk of the total mass — up to 95%, for example, in the Milky Way - our galaxy. Or it may be completely absent, as in some dwarf galaxies. They contain a lot of dust and gas and actively generate young stars.

The conditions for the birth of stars and galaxies arose long before the Big Bang. When the universe passed the age mark, plasma in outer space was replaced by a mixture of gases. This gas was still too hot to condense into the clouds that give rise to the stars. However, it was adjacent to dark matter particles distributed unevenly in space — where it was slightly denser, where it was rarefied. Clouds of dark matter combined into larger structures, despite the expansion of space. This is how clusters of clouds of dark matter arose, and then the first supermassive stars appeared, which quickly exploded and left behind black holes. Such stars could have already existed for billions of years and therefore were able to form star systems due to dark matter. This is how long-lived galaxies, including ours, arose.

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