MILKY WAY

Last updated: 18/06/2019

The Milky Way is a barred spiral galaxy and it is also the galaxy we live in. Spiral galaxies make up two-thirds of the galaxies in the Universe. Unlike a regular spiral, a barred spiral contains a bar across its center region and has two major arms. The Milky Way also contains two significant minor arms, as well as two smaller spurs. One of the spurs, known as the Orion Arm, contains the sun and the solar system. The Orion arm is located between two major arms, Perseus and Sagittarius. The Milky Way's radius is about 52,850 light years and is estimated to have over 200 billion stars, exoplanets, asteroid belts, and many other objects. Most stars have one or more planets that orbit them so there may be over 400 billion exoplanets. The galactic center, the center of the milky way, contains at least one supermassive black hole named Sagittarius A and is billions of times as massive as the Sun. Thank goodness our Solar System is located 25,000 light-years away from the Galactic center.

 The Milky Way is also part of 50 galaxies called the Local group, which also contains Andromeda, Triangulum and some smaller galaxies. Scientists claim that the Milky Way will collide with Andromeda in the future. The Local Group is part of a bigger system called the Virgo Supercluster of Galaxies, and that is part of an even larger group called the Laniakea Supercluster. 

In the 1920s, astronomers thought all of the stars in the universe were contained inside of the Milky Way. It wasn't until Edwin Hubble discovered a special star known as a Cepheid variable, which allowed him to precisely measure distances, that astronomers realized that the fuzzy patches once classified as nebula were actually separate galaxies. 

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