A galaxy is essentially a gravitating mass of stars, gases, dark matter, and dust which exists in space. The word “galaxy” is derived from the Greek word galaxia, literally meaning ” Milky Way”. In the ancient Greek and Roman mythology, the god of wine, Dionysus, was said to have forged an empire after crossing the Milky Way with his army. In modern times, the Milky Way is thought to be a super cloud or “worm cloud”, billions of light-year away, surrounded by a shell of gas and dust.
If you’re looking for a fun fact about galaxies, you’re not alone. There are millions of people who would love to know more about their place in the Universe. Fortunately, scientists today have many tools at their disposal. One popular tool used by astronomers is the Chandra X-Ray telescope, which is located by the Chandra observatory located on Hawaii’s Big Island. The telescope has enabled astronomers to discover many new planets around other stars, and even detected water vapor in the atmospheres of extrasolar planets. Now that we have the ability to study these faraway objects in detail using telescopes, we also know more about the properties of these faraway galaxies.
Astronomers have also discovered that most galaxies are made up of a “galaxy cluster”. A galaxy cluster is made up of a collection of several hundred galaxies, which are held together by their mutual gravity. Like our own Milky Way, all major galaxy clusters are relatively intact and much can be learned about in terms of composition, history, and structure. However, like our own galaxy, all of the clusters possess a vast amount of dark matter, making up about 90% of the entire volume of the Milky Way. This dark matter serves as a repository for cool gas and dust, which makes up about two-thirds of the gas in a galaxy.