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Here are the most amazing pictures of Colliding Galaxies or Interacting Galaxies. This is page 4 of the collection of the 50 most spectacular galaxy pictures of all time. Use the navigation pager near the bottom of each page to view all other pages. You can also view all the galaxy pictures along with their descriptions on a single page.
Most of the giant galaxies that we see today were built from many smaller galaxies that merged together. This is an ongoing process. Galaxies often interact gravitationally with each other. The gravity of one galaxy distorts the shape of another galaxy. In some cases, the gravity of the larger galaxy slowly pulls out stars and other matter from the smaller galaxy, and assimilates it within itself. This process is called tidal stripping. In other cases, the galaxies collide with each other. If the colliding galaxies do not have sufficient momentum to continue traveling after the collision, their mutual gravity pulls them back toward each other. They collide a number of times and eventually merge together.
A number of small satellite-galaxies revolve around the Milky Way Galaxy. Since the Milky Way Galaxy is the larger galaxy, its stronger gravity slowly pulls out stars and other matter from these satellite galaxies. The Milky Way Galaxy will slowly assimilate these satellite galaxies within itself. This process is called galactic cannibalism. Astronomers also predict that the Andromeda Galaxy will collide and merge with the Milky Way Galaxy in the distant future. When galaxies collide and merge, the individual stars of the galaxies do not smash with each other, because the distances between individual stars are too vast.
Just about one in a million galaxies can be caught in the act of colliding. However, in the early Universe, colliding galaxies and mergers might have been more common, since the Universe was smaller and the galaxies were closer together. The following pictures show how interacting galaxies distort the shapes of each other to form tail-like structures and other interesting patterns. The process of galactic interactions, collisions, and mergers can take hundreds of millions or even several billion years to complete.
NGC 3169 and NGC 3166 are interacting galaxies located about 70 million light-years away from the Earth in the direction of the Sextans constellation. Even thought these galaxies are separated by a distance of thousands of light-years, their shapes are getting distorted due to each others gravity. As shown in the above picture, the shape of the left galaxy (NGC 3169) is warped, and the dust lanes of the right galaxy (NGC 3166) are fragmented.
The above picture shows a pair of interacting galaxies located in the direction of the Bootes (Herdsman) constellation. Their distance from the Earth is about 200 million light-years. The arms and the spiral structure of the larger galaxy (NGC 5754) are getting slightly distorted by the gravity of the smaller galaxy (NGC 5752). The smaller galaxy is going through a starburst episode. Its core is surrounded by massive and luminous star clusters.
Like a pair of cosmic dancers holding hands, the interacting galaxies, NGC 5257 and NGC 5258 are connected to each other by a dim bridge of stars. They are located about 300 million light-years away from the Earth in the direction of the Virgo constellation. New stars are forming in their disks. Supermassive black holes are also thought to be present in their centers. This pair of interacting spiral galaxies is also called Arp 240.
The Mice Galaxies (NGC 4676) are a pair of interacting galaxies located about 300 million light-years away from the Earth in the direction of the Coma Berenices constellation. They are getting ripped apart due to each others gravity. They are likely to collide again and again till they merge with each other after several passes. The long tail-like structures are formed because the gravitational pull is stronger near those ends of the galaxies that are closer to each other than those that are far apart.
The above picture shows colliding galaxies NGC 2207 and IC 2163. They are located about 114 million light-years away from the Earth in the direction of the Canis Major (Great Dog) constellation. The larger galaxy on the left (NGC 2207) is distorting the shape of the smaller galaxy on the right (IC 2163), and flinging out stars and gas from it into long streamers that stretch for nearly 100,000 light-years. Trapped in a mutual orbit around each other, both the galaxies will distort and disrupt each other. They are participating in a cosmic dance, which will last for billions of years and end in the merger of the two galaxies. The above picture was released by ESO. For a Hubble Space Telescope image of the same colliding galaxies, see this picture.
The above picture shows Arp 272, a pair of colliding galaxies (NGC 6050 and IC 1179). Located about 450 million light-years away from the Earth in the direction of the Hercules constellation, these colliding spiral galaxies are in close contact with each other through their swirling arms. A third, smaller galaxy is also visible near the bottom of the image. It could also be interacting with them.
Arp 194 is a peculiar group of interacting galaxies located about 600 million light-years away from the Earth in the direction of the Cepheus constellation. In the top portion of the above picture, two colliding galaxies are in the process of merging together. It looks like one of the galaxies has sprung a leak -- a spiral arm full of newborn stars is extending downward. The bluish arm looks like a cosmic fountain of stars, gas and dust. It looks like it is connected to the galaxy at the bottom, but it isn't; the galaxy visible at the bottom of the picture is a background galaxy located very far away from the interacting galaxies.
The above picture shows the aftermath of a head-on galactic collision. The elliptical galaxy on the left has shot right through the center of the galaxy on the right, creating its ring-like shape. The collision has triggered intense star-formation activity in the bluish ring, which is all that remains of what might once have been a spiral galaxy. This pair of colliding galaxies is called Arp 147. It looks like the number 10. It is located more than 400 million light-years away from the Earth in the direction of the Cetus constellation.
The above picture of Stephan's Quintet (Hickson Compact Group 92) shows not just two, but four interacting galaxies. They are locked in a cosmic dance of repeated close encounters. This compact group is named after Édouard Jean-Marie Stephan, a French astronomer who discovered it in 1877. It lies in the Pegasus constellation. As the name implies, we can see five galaxies in the group. However, the galaxy in the lower left of the picture is a foreground galaxy, located only about 40 million light-years away from the Earth. It is not a part of the group of the remaining four interacting galaxies that are located about 290 million light-years away from the Earth. The two colliding galaxies in the center of the picture appear very close to each other. Their interactions have triggered a frenzy of new star births. The shape of the barred spiral galaxy in the top right corner of the picture looks distorted. In fact, the shapes of all the three galaxies are distorted due to gravitational forces. Their spiral arms look very elongated. Long, tidal tails can also be seen. They are studded with a large numbers of star clusters. The elliptical galaxy in the lower right corner is less affected by the interactions. This video shows a simulation of multiple-galaxy collision.
The above Hubble Space Telescope picture show 12 different pairs of interacting or colliding galaxies. The process of galactic interactions, collisions, and mergers takes hundreds of millions of years (or even several billion years) to complete. The above galaxies are in different stages of their interactions/collisions, and this can help us understand the process better. Notice how their shapes are distorted by their gravities, and how they form peculiar shapes.