A close up photo of the Orion Nebula So named because it is found in the constellation Orion. All nebulas are very large clouds of gas and dust. As gravity draws these clouds into smaller clumps of matter they eventually become so dense that nuclear fusion spontaneously begins. Then a star is born, producing light. Independently found by Johann Baptist Cysatus in 1611. Trapezium cluster found as multiple star by Galileo Galilei in 1617. The Orion Nebula Messier 42 (M42, NGC 1976) is the brightest starforming, and the brightest diffuse nebula in the sky, and also one of the brightest deepsky objects at all. Shining with the brightness of a star of 4th magnitude, it visible to the naked eye under moderately good conditions, and rewarding in telescopes of every size, from the smallest glasses to the greatest Earth-bound observatories as well as outer-space observatories like the Hubble Space Telescope. It is also a big object in the sky, extending to over 1 degree in diameter, thus covering more than four times the area of the Full Moon. As it is so well visible to the naked eye, one may wonder why its nebulous nature was apparently not documented before the invention of the telescope. Only some Central American, Mayan folk tales may be interpreted in a way suggesting that these native Americans may have known of this nebulous object in the sky (O'Dell 2003, p. 3). However, the brightest stars within the nebula were noted early and cataloged as one bright star of about fifth magnitude: In about 130 AD, Ptolemy included it in his catalog, as did Tycho Brahe in the late 16th century, and Johann Bayer in 1603 - the latter cataloging it as Theta Orion in his Uranometria. In 1610, Galileo detected a number of faint stars when first looking at this region with his telescope, but didn't note the nebula. Some years later, on February 4, 1617, Galileo took a closer look at the main star, Theta1, and found it to be triple, at his magnification of 27 or 28x, again not perc