M33 The Triangulum galaxy

Fred Calvert, Cold Spring Observatory

 The Triangulum galaxy is the third largest of the local group of about 44  galaxies.  It has an estimated diameter of 60,000 light years and is composed of an estimated 40 billion stars. The largest galaxy in the local group is the Andromeda galaxy with an estimated diameter of 220,000 light years and 1 trillion stars. Our home the Milky Way galaxy is the second largest of the group with an estimated diameter of 120,000 light years and 400 billion stars. The Triangulum galaxy is thought to be gravitationally bound to the larger Andromeda galaxy. Both are approaching our Milky Way galaxy at about 68 miles per second and all three will collide in about 4 billion years to form a new, larger galaxy. The galaxy was first described around 1654 by Italian astronomer Giovanni Battista Hodierna in his written works. Charles Messier also independently discovered the galaxy in 1764 and cataloged it as object 33; hence the name M33.Data for this image was acquired with a Planewave 17" f/4.5 telescope and FLI-PL6303E CCD Camera. Total exposure time was 2.5 hours.

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