GALAXIES
Last updated: 18/06/2019
A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. The word galaxy came from the Greek word galaxias, meaning milky. The galaxy that the Solar System is in is called the Milky Way galaxy and the closest spiral galaxy is the Andromeda galaxy. But there is a dwarf galaxy closer to us called Canis Major Dwarf Galaxy.
There are three types of galaxies. Elliptical, spiral, and irregular galaxies.
1.Elliptical
An elliptical galaxy is a type of galaxy with an approximately ellipsoidal shape and a smooth, nearly featureless image. They are one of the three main classes of galaxy described by Edwin Hubble in his Hubble sequence and 1936 work The Realm of the Nebulae, along with spiral and lenticular galaxies.
2.Spiral
Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, form part of the Hubble sequence. Most spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as the bulge. The Milky Way is a barred spiral galaxy.
3.Irregular
An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy. Irregular galaxies do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, with neither a nuclear bulge nor any trace of spiral arm structure.
The Milky Way is about 100,000 light-years across and contains billions of stars. Most stars have their own planets that orbit them. These planets are usually referred to as exoplanets. Even though the Milky Way is huge, it is nothing when you compare it to IC 1101. This galaxy is the largest galaxy discovered in the Universe till today! Its radius is estimated to be about 1.9569 million light years but some estimates suggest that IC 1101 is 6 million light-years in diameter. The galaxy alone is located 1.045 billion light years away from the Earth.