The Milky Way: Our Home Galaxy
The Milky Way is an enormous barred spiral galaxy (i.e, a barred spiral galaxy is a type of galaxy that has several spiral arms) that is home to our Sun and hundreds of billions of stars. It has a huge size, measuring 100,000 light-years in diameter! Our Solar System lies around 25,000 light-years from the centre of the Milky Way. Just like the planets orbit the Sun, the Solar System orbits the centre of the Milky Way, completing one orbit in about 250 million years. It is a huge collection of nebulae, hundreds of billions of stars, planets and millions of black holes.
The Centre of the Milky Way
The centre, also known as the nucleus of the Milky Way is a densely populated region with many nebulae and stars. Also, there is a Supermassive Black Hole at the centre of the Milky Way and it is known as Sagittarius A*. Sagittarius A* is so small that it would fit inside Mercury’s orbit yet it is so massive that it would weigh 4 Million times the mass of the Sun! Everything else in the galaxy orbits this Supermassive Black Hole, although it is not the gravitational effect of the Black Hole itself but is the effect of Dark Matter (i.e, a hypothetical form of matter that interacts well with gravity but not with light) that is acting upon everything in the galaxy.
The Milky Way in the Night Sky
In Dark Sky locations, you will be able to see a band of many nebulae and hundreds of stars. This is the Milky Way. In that band, you can also see dust in the band that blocks the light from the stars that are behind it.
The satellite galaxies of the Milky Way
The Milky Way has at least 10 orbiting satellite galaxies, two of which are the major ones — the Large Magellanic Cloud and the Small Magellanic Cloud. The Large Magellanic Cloud lies about 158,200 light-years away from Earth and measures around 14,000 light-years in diameter. The Small Magellanic Cloud lies about 199,000 light-years from Earth and measures around 7,000 light-years in diameter.
