Messier 33 – The Triangulum Galaxy

One of our closest galactic neighbors is Messier 33 (M33), the Triangulum Galaxy. Current thinking is that it is roughly 2.8 million light years from Earth (although older estimates had placed it closer to 2.3 million light years). It’s the third largest galaxy in our local group of galaxies smaller only than the Andromeda Galaxy (Messier 31) and our own Milky Way.

M33 is a serious star factory. It, in fact, contains one of the largest star-forming HII regions known. It even has its own NGC number, NGC 604, and is clearly visible in the frame. It’s about 1,500 light years across and shares many of the characteristics found in the Great Orion Nebula in our galaxy, which is only 25 to 30 light years in breadth. It contains a number of other large star-forming regions as well. These are discussed in more detail in this poster I put together of close shots of these nebulas.(link to poster).

We may get to know M33 really well in a few billion years. It appears to be gravitationally bound to M31, the Andromeda Galaxy, and both are moving toward us.