Of the major star systems close to us is the Andromeda nebula (M31) is a spiral galaxy, 2.6 times larger in size, our home galaxy the milky Way: its diameter is 260 thousand light-years. The Andromeda nebula is at a distance of 2.5 million light years (772 KPS) from us, and her weight is 300 billion Solar masses. It contains about a trillion stars (for comparison: in the milky Way is about 100 billion stars).
The Andromeda galaxy is the most distant cosmic object, which can be seen in the sky (Northern hemisphere) to the naked eye even in urban lighting - it looks like a glowing fuzzy oval. It should be remembered that due to the fact that the light from the Andromeda galaxy is 2.5 million years, we see it as it was 2.5 million years ago, and don't know how she currently looks.
The Andromeda Galaxy
And the position of the galaxy in the sky
B - Andromeda galaxy in ultraviolet rays
Astronomers have found that the Andromeda galaxy and our Galaxy are approaching each other with a speed of 100-140 km/s Approximately 3-4 billion years, perhaps there will be a collision and then they will merge into one giant galaxy. Those who are concerned about the fate of the Solar system as a result of this collision, we hasten to reassure: any exposure to the Sun and planets, most likely, will not happen. The mergers of galaxies are not accompanied catastrophic stellar collisions, as distances between stars are very large compared to the sizes of the stars.
But do not think that the process of merging galaxies, spanning millions of years, there is no dramatic effects. When the convergence of the two galaxies were the first to touch the clouds of interstellar gas. Due to the rapid convergence of the density sharply increases, they warmed up, and the rising pressure makes the gas-dust clouds in the formation of new stars. Begins a rapid, explosive process of star formation, accompanied by flashes, explosions and throwing out monstrously long jets of dust and gas.
Model merging galaxies the milky Way and the Galaxy of Adromeda
But back to our neighbors. Second our nearest spiral galaxy - m. It is in the constellation of the Triangle and is removed from us by 2.4 million light years. In diameter it is 2 times smaller than the milky Way and 4 times less than the Andromeda galaxy. It can also be seen with the naked eye, but only in the moonless night outside of the city. It looks like a dull misty speck triangle between the α and τ Fish.
And the position of the galaxy in the sky
B - galaxy Triangle (photo by NASA in the ultraviolet and visible range)
The rest of the galaxy, our nearest environment is a dwarf elliptical and irregular galaxies. The nearest to us of irregular galaxies, the most interesting are two: the Large and Small Magellanic Clouds.
The Magellanic Clouds are the satellites of our milky Way Galaxy. They are also visible to the naked eye, but only in the southern hemisphere. The large Magellanic cloud in the constellation Gold Fish. It is removed from us by 170 thousand light-years (50 KPS), with a diameter of 20 thousand light years, and it contains about 30 billion stars. Despite belonging to the type of irregular galaxies, the Large Magellanic Cloud has a structure close to the rugged spiral galaxies. It has all those types of stars known in the milky Way. In the Large Magellanic cloud detected another point of interest is one of the brightest among the famous dust complex with a length of 700 light years - the tarantula nebula, a hotbed of star formation.
The Tarantula Nebula
Shooting using the TRAPPIST telescope (Observatory, La Silla, Chile)
The small Magellanic Cloud 3 times less Great and also reminds him rugged spiral galaxy. It is located in the constellation of the Toucan, next to a Gold Fish. The distance to this galaxy 210 thousand light-years (60 KPS).
The large and Small Magellanic clouds
The Magellanic Clouds are surrounded by a common envelope of neutral hydrogen, which is called the Magellanic System.
Both Magellanic clouds are victims of galactic cannibalism on the part of the milky way: the gravitational influence of our Galaxy gradually destroys them and attracts the substance of these galaxies. Hence irregular shape of the Magellanic Clouds. Experts believe that it is the remains of two small galaxies in the process of gradual extinction. According to the calculations of astronomers, in the next 10 billion years the milky Way will fully absorb all the substance of the Magellanic Clouds. Among the Magellanic clouds occur similar processes: due to its gravity in the Large Magellanic cloud "steal" millions of stars of the Small Magellanic cloud. Perhaps this fact explains the high zvezdoobrazovaniya acitvely in the tarantula nebula: this area is right in the path of the gas stream, which pulls the gravity of the Large Magellanic cloud Small.
Thus, for example, occur in the vicinity of our Galaxy once again, you can see that the merger of galaxies and absorption of small galaxies larger - quite common in galactic life.
Our Galaxy, the Andromeda galaxy and galaxy Triangle are a group of galaxies connected by the gravitational interaction. It is called the Local group of galaxies. The size of the Local group - 1,5 megaparsecs in diameter. Besides the three large spiral galaxies in the Local group includes more than 50 dwarf and irregular (form) of galaxies. So, the Andromeda galaxy is at least 19 galaxies, satellites of our Galaxy known 14 satellites (as of 2005). In addition, in the Local group includes other dwarf galaxies that are not satellites of larger galaxies.