Milky Way Galaxy Facts
The Milky Way Galaxy is our home galaxy in the universe. It is a fairly typical barred spiral with four major arms in its disk, at least one spur, and a newly discovered outer arm. The galactic centre, which is located about 26,000 light-years from Earth, contains at least one supermassive black hole (called Sagittarius A*), and is crossed by a bar. The Milky Way began forming around 12 billion years ago and is part of a group of about 50 galaxies called the Local Group. The Andromeda Galaxy is part of this group as are numerous smaller galaxies, including the Magellanic Clouds. The Local Group itself is part of a larger gathering of galaxies called the Virgo Supercluster of galaxies.
Milky Way Galaxy Profile
|Diameter:||100,000 – 180,000 ly|
|Distance to Galactic Centre:||27,000 ly|
|Mass:||800 – 1,500 M☉|
|Age:||13.6 Billion years|
|Number of Stars||100 – 400 billion|
Facts about the Milky Way
- The Milky Way began as a series of dense regions in the early universe not long after the Big Bang. The first stars to form were in globular clusters that still exist. They are among the oldest stars formed in the Milky Way region.
- The Milky Way has grown by merging with other galaxies through time. It is currently acquiring stars from a very small galaxy called the Sagittarius Dwarf Spheroidal, as well as gobbling up material from the Magellanic Clouds.
- The Milky Way moves through space at a velocity of about 343 miles per second with respect to the Cosmic Microwave Background radiation.
- The Milky Way’s central core contains a supermassive black hole. It is commonly referred to as Sagittarius A*. It contains the mass of about 4.3 million Suns.
- The stars, gas and dust of the Milky Way all orbit the center at a rate of about 136 miles per second. This constant rate for all stars at different distances from the core implies the existence of a shell of dark matter surrounding our galaxy.
- Our galaxy will collide with Andromeda Galaxy in about 5 billion years. Some astronomers refer to our two galaxy as a binary system of giant spirals.
Andromeda Galaxy Facts
Andromeda Galaxy (M31) is the closest large galaxy to the Milky Way and is one of a few galaxies that can be seen unaided from the Earth. In approximately 4.5 billion years the Andromeda Galaxy and the Milky Way are expected to collide and the result will be a giant elliptical galaxy. Andromeda is accompanied by 14 dwarf galaxies, including M32, M110, and possibly M33 (The Triangulum Galaxy).
Andromeda Galaxy Profile
|Designation:||M31 or NGC 224|
|Mass:||1,230 billion M☉|
|Number of Stars||1 trillion|
Facts about Andromeda
- While Andromeda is the largest galaxy in the Local Cluster it may not be the most massive. The Milky Way 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 black hole hidden at the core.
- 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 lights in order to see it.
Sombrero Galaxy Facts
The Sombrero Galaxy is one of the most unusual looking barred spiral galaxies visible from Earth. Its bright nucleus, large central bulge and spiral arms threaded through with a thick dust lane make it look a little like a hat from Mexico. The dust lane is a ring that circles the bulge of the galaxy, and it is rich with gas, dust, and hydrogen gas. Because it has all the elements needed for star formation, it’s not surprising that astronomers have found many sites of star formation inside.
Sombrero Galaxy Profile
|Designation:||M104 or NGC 4594|
|Mass:||800 billion M☉|
Facts about the Sombero Galaxy
- The Sombrero Galaxy may not be part of a formal galaxy group, but could be a member of a string of galaxies that extends away from the Virgo Cluster.
- As many as 2,000 globular clusters swarm around the core of the Sombrero Galaxy, and the number could be related to the size of the central bulge.
- The Sombrero has a central supermassive black hole at its heart. Observations of star motions near the black hole suggest it could have the mass of a billion Suns, perhaps the most massive of any black hole found so far at the heart of a galaxy.
- The Sombrero Galaxy is a favorite target for well-equipped amateur astronomers. If you have a good dark-sky sight, it can be spotted through binoculars; those with large telescopes can spot the dust lane. The Sombrero is a spring and early summer observing object half-way between the constellations Virgo and Corvus.
- NASA’s Hubble Space Telescope and Spitzer Space Telescope have been used to study the Sombrero in visible and infrared light. The starbirth regions stand out in infrared wavelengths are are mostly located along the outer rim of the dust ring surrounding the galaxy’s core.
- The Sombrero Galaxy looks as it does partly because we are viewing it “edge on” from our point of view here on Earth.