Galaxies

For today's post, we are going to look at different galaxies. But now we are going to look at the three major galaxies, Spiral Galaxy, Elliptical Galaxy and Irregular Galaxy. I have information and I've drawn how those three galaxies look like. Comment down below what you have learnt. Have a cool day!! Bye!!

Left: Spiral Galaxy
Centre: Elliptical Galaxy
Right: Irregular Galaxy

Spiral Galaxy

The Hubble Sequence

Spiral Galaxies are spiral shaped galaxies. Scientists observe that most of the galaxies in the universe are spiral galaxies. Most spiral galaxies have a central bulge surrounded by a flat rotating disk of stars. About two-thirds of spiral galaxies contain a structure through the centre, making spiral galaxies a minority. The Milky Way is one of those.

In 1926, Edwin Hubble came up a system to classify galaxies. Known as the Hubble Sequence, it organises galaxies base on their shape.

Spiral galaxies make up about 77 percent of the galaxies. Spiral galaxies are filled with gas and dust, which results in a wealth of a star formation. They are considered to be younger than elliptical galaxies, which contains less dust and form fewer stars. The twisted galaxies range from a billion to a trillion times as massive as the sun. The largest known spiral galaxy is NGC 6872, about 5 times the size of the Milky Way. The oldest observed spiral galaxy BX442 is about 10.7 billion years old. Because of the distance and the amount of time to travel, scientists are about to see the galaxy only 3 billion years after the Big Bang formed in the universe.

Elliptical Galaxy

In 1926, Edwin Hubble came up a system to classify galaxies. Known as the Hubble Sequence, it organises galaxies base on their shape. Galaxies classified as E0 Galaxy appear to be almost perfect circles (ellipse). Elliptical galaxies have a broader range size than other types of galaxies. The smallest galaxies are dwarf elliptical galaxies, which is less than 10 percent the size of the Milky Way, and could contain only 10 million times the mass of the sun. Some ellipticals can also be stretched to more than a million light-years across, that can contain more than ten trillion stars. M87 (Messier 87) is identified as one of the largest galaxies in the universe. But astronomers have found more spiral galaxies than elliptical galaxies. As spiral galaxies are bright, elliptical galaxies are dim. Elliptical galaxies contain less gas and dust, which means few new stars are born.

Irregular Galaxy

Irregular Galaxies don't have a specific shape, they're all different. Any galaxies that don't fit into one of the other galaxy groups are called an irregular galaxy. Irregular galaxies are the smallest group that is seen by astronomers. The stars in an irregular galaxy are usually young, very bright stars. Most irregular galaxies have the right conditions to make new stars. Like our moon orbits the Earth, some irregular galaxies orbit around other galaxies, those galaxies are called starburst galaxies, these galaxies are very bright because they have many new stars in them. Irregular galaxies form in different ways. Some of the ways are formed when they bump into, galaxies collide or get too close.