Andromeda galaxy

Designation: M31 or NGC 224 Type: Spiral Diameter: 220,000 ly Distance: 2.54 Mly Mass: 1,230 billion M☉ Number of Stars 1 trillion Constellation: Andromeda Group: Local Group Facts about Andromeda • While Andromeda is the largest galaxy in the Local Cluster it may not be the most massive. The Milky May is thought to contain more dark matter, which could make it much more massive. • Since it is the nearest spiral galaxy to us, astronomers use the Andromeda Galaxy to understand the origin and evolution of such galaxies. • The Andromeda Galaxy is approaching the Milky Way at approximately 100 to 140 kilometres per second. • The Andromeda Galaxy has a very crowded double nucleus. Not only does it have a massive star cluster right at its heart, but it also has at least one supermassive • The spiral arms of the Andromeda Galaxy are being distorted by gravitational interactions with two companion galaxies, M32 and M110. • The Andromeda Galaxy has at least two spiral arms, plus a ring of dust that may have come from the smaller galaxy M32. Astronomers think that it may have interacted more closely with Andromeda several hundred million years ago, when M32 plunged through the heart of its larger neighbor. • There are at least 450 globular clusters orbiting in and around the Andromeda Galaxy. Some of them are among the most densely populated globulars ever seen. • The Andromeda Galaxy is the most distant object you can spot with the naked eye. You need a good spot away from bright l...

Galaxies are vast cosmic islands of stars, gas, dust, and dark matter held together by gravity. Hubble’s keen eye has revealed intricate details of the shapes, structures, and histories of galaxies — whether alone, as part of small groups, or within immense clusters. From supermassive black holes at galactic centers to giant bursts of star formation to titanic collisions between galaxies, these discoveries allow astronomers to probe the current properties of galaxies as well as examine how they formed and developed over time. What Kinds of Galaxies Are There? Astronomers classify galaxies into three major categories: elliptical, spiral and irregular. These galaxies span a wide range of sizes, from dwarf galaxies containing as few as 100 million stars to giant galaxies with more than a trillion stars. Ellipticals, which account for about one-third of galaxies observed, vary from nearly circular to very elongated. They possess comparatively little gas and dust, contain older stars and are not actively forming stars anymore. The largest and rarest of these, called giant ellipticals, are about 300,000 light-years across. Astronomers theorize that these are formed by the mergers of smaller galaxies. Much more common are dwarf ellipticals, which are only a few thousand light-years wide. Spiral galaxies appear as flat, blue-white disks of stars, gas and dust with yellowish bulges in their centers. These galaxies are divided into two groups: normal spirals and barred spirals. In b...