WRITE A ESSAY ABOUT GALAXY
Answers
Explanation:
A galaxy is a group of many stars, with gas, dust, and dark matter.[1][2][3] The name 'galaxy' is taken from the Greek word galaxia meaning milky, a reference to our own galaxy, the Milky Way.
Gravity holds galaxies together against the general expansion of the universe.[3] In effect, the expansion of the universe takes place between groups of galaxies, not inside those groups. Gravity holds the galaxy together, and the same applies to groups of galaxies, such as our Local Group in the Milky Way. The gravitation is produced by the matter and energy in a galaxy or group of galaxies. Everything in a galaxy moves around a centre of mass, which is also an effect of gravity.
There are various types of galaxies: elliptical, spiral and lenticular galaxies, which can all be with or without bars. Then there are irregular galaxies. All galaxies exist inside the universe. The observable Universe contains more than 2 trillion (1012) galaxies[4] and, overall, as many as an estimated 1×1024 stars[5][6] (more stars than all the grains of sand on planet Earth).
There are galaxies of different sizes. Typical galaxies range from dwarfs with as few as ten million[3][8] (107) stars up to giants with a hundred trillion[3][9] (1014) stars, all orbiting the galaxy's center of mass. Galaxies may contain many multiple star systems, star clusters, and various interstellar clouds. The Sun is one of the stars in the Milky Way galaxy; the Solar System includes the Earth and all the other objects that orbit the Sun.
Star clusters are not galaxies, they are inside galaxies. Globular clusters are spherical-shaped star clusters which are part of the outer halo of the Milky Way. One of the largest (and oldest) known star clusters, Messier 15, has several million stars, packed closely together, with a black hole at its centre. The stars are too closely packed to get an accurate count, but it certainly has more stars than some of the smaller galaxies.
Within galaxy clusters, galaxies move relative to other galaxies. They can and do collide. When this happens, the stars generally move past each other, but gas clouds and dust interact, and can form a burst of new stars. Gravity pulls both galaxies into somewhat new shapes, forming bars, rings or tail-like structures.
Answer:
GALAXIES
Nearly all the matter within the universe is focused in galaxies. A galaxy may be a gigantic mass of stars command along by gravity. the most important contain numerous stars. the tiniest have simply many million, however even little galaxies are thus massive that lightweight takes thousands of years to cross them. Despite having such a lot matter, galaxies are principally empty area, with Brobdingnagian distances between every star. Our sun and every one the celebrities we are able to see with the eye belong to only one galaxy - the Milky Way Galaxy. beyond side this lie billions of galaxies stretching as far into area as astronomers will see.
1) Spiral Galaxies
The most spectacular galaxies are spiral. These rotate like large whirlpools, spreading their stars into swish trailing arms. The oldest stars are settled in an exceedingly dense central hub. The spiral arms contain young stars, pink nebula's, and dark lanes of gas and mud. Spiral galaxies are disk-shaped, so that they seem flat if we have a tendency to see them from the aspect. Our Milky Way Galaxy may be a galaxy.
2) Cosmic Collision
Most galaxies are unbelievably way apart, however some get shut enough to collide. This image shows 2 spiral galaxies bally into one another. Their cores are orange. Individual stars don't collide, however dirt clouds do, triggering a firestorm of star birth. The clusters of newborn stars during this