The spiral nebula, conjointly called Messier thirty one, M31, or NGC 224, may be a extragalactic nebula just about 780 kiloparsecs (2.5 million light-years) from Earth, and therefore the nearest major galaxy to the Milky Way. Its name stems from the realm of the Earth’s sky during which it seems, the constellation of Andromeda.
The virial mass of the spiral nebula is of an equivalent order of magnitude as that of the Milky Way, at a trillion star lots (1012M☉). The mass of either galaxy is troublesome to estimate with any accuracy, however it had been long thought that the spiral nebula is additional huge than the Milky Way by a margin of some twenty fifth to five hundredth. This has been referred to as into question by a 2018 study that cited a lower estimate on the mass of the spiral nebula, combined with preliminary reports on a 2019 study estimating a better mass of the Milky Way. The spiral nebula contains a diameter of concerning 220,000 light-years, creating it the biggest member of the native cluster a minimum of in terms of extension, if not mass.
The number of stars contained within the spiral nebula is calculable at one trillion (1×1012), or roughly doubly the amount calculable for the Milky Way.
The Milky Way and Andromeda galaxies ar expected to collide in ~4.5 billion years, merging to make an enormous elliptical galaxy or an outsized convexo-convex galaxy. With a visible magnitude of three.4, the spiral nebula is among the brightest of the Messier objects creating it visible to the eye from Earth on moonless nights, even once viewed from areas with moderate lightweight pollution.
The spiral nebula is approaching the Milky Way at concerning one hundred ten kilometres per second (68 miles per second). it’s been measured approaching relative to the Sun at around three hundred km/s (190 mi/s) because the Sun orbits round the center of the galaxy at a speed of roughly 225 km/s (140 mi/s). This makes the spiral nebula one in all concerning one hundred noticeable blueshifted galaxies. Andromeda Galaxy’s tangential or sideways speed with relevancy the Milky Way is comparatively abundant smaller than the approaching speed and thus it’s expected to collide directly with the Milky Way in concerning four billion years. a probable outcome of the collision is that the galaxies can merge to make an enormous elliptical galaxy or maybe even an outsized disc galaxy. Such events ar frequent among the galaxies in galaxy teams. The fate of the world and therefore the system within the event of a collision is presently unknown. Before the galaxies merge, there’s atiny low likelihood that the system may well be ejected from the Milky Way or be a part of the spiral nebula.
