In the solar system, Mars and Venus are our closest neighbors. In the universe, our home is the Milky Way galaxy. Our neighbors in the universe belong to the Local Group of galaxies. This group is made up of 30-50 galaxies located within 4 million light years of our galaxy. Three of these are large spiral galaxies just like the Milky Way. The rest are irregular dwarf galaxies. Here are the four nearest galaxies to the Milky Way.
Canis Major Dwarf Galaxy
The Canis Major Dwarf galaxy is currently considered the nearest galaxy to ours. It was only discovered recently in 2003 because it is hidden by a thick cloud of dust and is not visible in visible light. It only reveals itself in infrared light. Astronomers discovered it when analyzing infrared images of our galaxy.
This galaxy lies 25,000 light years away from our sun in the Canis Major constellation and 42,000 light years from the core of our galaxy center. We are about 26,000-28,000 light years from the center of our galaxy. This means that we are closer to the Canis Major Dwarf galaxy than to the center of our galaxy.
Unlike our galaxy’s spiral shape, this one is irregular and elliptical. It is home to more than a billion stars. Most of them are red dwarf stars (cool, red stars that shine brightly in the infrared). It orbits the Milky Way and its materials are pulled apart by our galaxy’s strong force of gravity leaving a long stream of gases, stars and dust on its path. This stream is a 200,000 light years long filament known as Monocerous ring.
Sagittarius Dwarf Elliptical Galaxy (SagDEG)
The second nearest galaxy to ours is the Sagittarius Dwarf galaxy. It was discovered in 1994 because it is very dimmed and hidden from view by gases, dust and stars in the central part of our galaxy.
Cosmologists were studying stars near the region of our galaxy when they noticed a group of stars too far away to be part of our galaxy and moving in the opposite direction. They realized they had discovered another galaxy that was trying to pass though the Milky Way getting ripped and distorted by our galaxy’s strong gravity.
It is located at the far side of our galaxy from our sun. Its home is in the Sagittarius constellation 70,000 light years away from us. It is so near our galaxy that some of its stars have crossed over to our side.
It completes one orbit of our galaxy in one billion years and is being slowly swallowed up by the Milky Way. It probably won’t complete the next orbit since it might already be swallowed completely by our galaxy. Mathematical models predict a collision between the two galaxies in the distant future.
The Large and Small Magellanic Clouds
The Large Magellanic Clouds (LMC) and Small Magellanic Clouds (SMC) galaxies are the third closest galaxies to us. They were thought to be our nearest neighbors until 1994.
LMC is about 180,000 light years away while SMC is about 210,000 light years away from us. They can be seen with the unaided eye looking from countries south of the equator. They appear as conspicuous objects in the Southern hemisphere sky.
Ancient southern astronomers actually knew them although not much was recorded about them until 1519 when Magellan publicized them in his trip in 1519. They were named after him.
Both are irregular dwarf galaxies. SMC is a distorted disk probably deformed by the strong tidal forces of the LMC and Milky Way galaxies.
The Large Magellanic cloud galaxies are home to interesting phenomenon including a variety of nebulas and clusters.
The Andromeda Galaxy
Although it is not the closest galaxy overall, the Andromeda galaxy is the nearest spiral galaxy to our own. It lies about 2.5 million light years away from us in the Andromeda constellation. It is also known as Messier 31, M31 and NGC 224 and is the largest galaxy in the local group galaxies. However, the Milky Way contains more dark matter making it more massive.
You can see its central region with the naked eye on a moonless night sky just like ancient star gazers could see it. Initially, it wasn’t clear whether it was a galaxy or just a cloud of gas. It was in the 1920s that astronomer Edwin Hubble confirmed that Andromeda was indeed a galaxy.
According to the Spitzer Space Telescope, Andromeda has at least one trillion stars. This is at least double the stars in the Milky Way galaxy.
The Andromeda galaxy and the Milky Way galaxy are predicted to collide in about 3.75 billion years, merge and form a giant elliptical galaxy.
The Triangulum galaxy is the third spiral galaxy and the third largest galaxy in the Local Group of galaxies with a diameter of about 50,000 light years and a concentration of about 40 billion stars. Its other names are Messier 33 or NGC 598 or Pinwheel Galaxy. It was first discovered by Giovanni Battista in the 16th century and was first identified by Charles Messier in 1764.
It lies about 3 million light years away from Earth in the constellation Triangulum. It is one of the most distant objects visible with the naked eye. However, it is a faint galaxy and not easily seen unless you know where to look and observe in dark skies.
The Triangulum is moving towards the Andromeda galaxy which is approaching our galaxy. This means that it is drifting towards the Milky Way galaxy.