Sombrero Galaxy

A galaxy is an enormous collection of a few million to trillions of stars, gas, and dust held together by gravity. They can be several thousand to hundreds of thousands of light-years across. Galaxies with less than a billion stars are considered “small galaxies.” In our own galaxy, the sun is just one of about 100 billion stars. Galaxy Origins Most astronomers suggest that galaxies formed shortly after a cosmic “big bang” that began the universe some 10 billion to 20 billion years ago. In the milliseconds following this explosion, clouds of gases began to coalesce, collapse, and compress under gravity to form the building blocks of galaxies. Scientists are divided on just how galaxies first formed. Some believe that smaller clusters of about one million stars, known as globular clusters, formed first and later gathered into galaxies. Others believe that galaxies formed first and that only later did the stars within them begin to gather into smaller clusters..

Andromeda galaxy

Galaxies are classified into three main types: spiral galaxies, elliptical galaxies, and irregular galaxies. Spiral galaxies, such as the Milky Way, consist of a flat disk with a bulging center and surrounding spiral arms. The galaxy’s disk includes stars, planets, dust, and gas—all of which rotate around the galactic center in a regular manner. This spinning motion, at speeds of hundreds of kilometers per second, may cause matter in the disk to take on a distinctive spiral shape like a cosmic pinwheel. Some spiral galaxies obtain even more interesting shapes that earn them descriptive names, such as sombrero galaxies…

Ring galaxy

Older stars reside in the bulge at the center of the galactic disk. Many new stars also form in spiral systems, and their disks are surrounded by a halo, which scientists believe is rich with mysterious dark matter. Elliptical galaxies are shaped as their name suggests. They are generally round but stretch longer along one axis than along the other. Elliptical galaxies contain many older stars, up to one trillion, but little dust and other interstellar matter. Their stars orbit the galactic center, like those in the disks of spiral galaxies, but they do so in more random directions. ….

Tadpole Galaxy

The universe’s largest known galaxies are giant elliptical galaxies, which may be as much as two million light-years long. Elliptical galaxies may also be small, in which case they are dubbed dwarf elliptical galaxies. NGC 5866, an example of a lenticular galaxy Peculiar galaxies are galactic formations that develop unusual properties due to tidal interactions with other galaxies. An example of this is the ring galaxy, which possesses a ring-like structure of stars and interstellar medium surrounding a bare core. A ring galaxy is thought to occur when a smaller galaxy passes through the core of a spiral galaxySuch an event may have affected theAndromeda Galaxy, as it displays a multi-ring-like structure when viewed in infrared radiation. A lenticular galaxy is an intermediate form that has properties of both elliptical and spiral galaxies. These are categorized as Hubble type S0, and they possess ill-defined spiral arms with an elliptical halo of stars.Barred lenticular galaxies receive Hubble classification SB0.) I Galaxies that are not spiral or elliptical are called irregular galaxies. Irregular galaxies appear misshapen and lack a distinct form, often because they are within the gravitational influence of other galaxies close by…. Today we classify galaxies mainly into two major groups following Hubble’s examples. Elliptical galaxies range from round shapes (E0) to oval shapes (E7). Spiral galaxies have a pinwheel shape and are classified according to their bulge, as well as how tightly their arms are wrapped around the bulge. They range from Sa, which has a large bulge and tight, smooth arms, to Sc, which has a small bulge and loose, lumpy arms. Barred spiral galaxies classified as SB are pinwheel-shaped and have a distinct “bar” of stars, dust and gas across their bulge.

Antennae galaxy

They range from an SBa, which has a bar across its large bulge and tight, smooth arms, to an SBc, which has a bar across its small bulge and loose, lumpy arms. Irregular galaxies have no definite shape but still contain new stars, gas, and dust. The closest spiral galaxy is Andromeda, a galaxy much like our own Milky Way. It is 2.2 million light years away from us. Andromeda is approaching our galaxy at a rate of 670,000 miles per hour. Five billion years from now it may even collide with our Milky Way galaxy. I