It is the most famous multiple star system in the entire night sky and one of the youngest star clusters known. The Trapezium can be seen here as four stars very close together in the center of the brightest part of the nebula. These stars have condensed and formed out of the gas and dust that make up the Orion Nebula. This image is a very close approximation of "true color" for the nebulosity in this region. Most deep-sky astronomical objects are too faint to show color visually. One of the few that is bright enough to show color in the eyepiece of a telescope is M42. For observers with good color vision, the bright core of M42 is usually reported as being blue-green in color. Some keen-eyed observers sometimes report some red also under dark skies with big telescopes. The blue-green comes from the emission of light of Oxygen III emissions in the nebula mixed with a smaller amount of bluer light from the hydrogen-beta emission line. This is the area of the spectrum to which human vision is most sensitive. If a nebula is bright enough to excite the color sensitive cells in the retinas of our eyes, the color we usually see first is blue-green. Most emission nebulas are recorded as very red in long-exposure images. The red comes from hydrogen-alpha emissions in the red portion of the spectrum which are actually the strongest emission lines in the nebula. Human vision, however, is not very sensitive to these wavelengths. So although red hydrogen-alpha emissions are the majority of light in most emission nebulas and are usually recorded as red in long-exposure photographs, this is not the way we usually see them through a telescope. Long-exposure astrophotos, if taken carefully, can reproduce reasonably accurate colors. These colors are really there in the deep sky objects, they are just too faint for us to see visually. This image was taken with a telescope with 70mm of aperture in visible light with an unmodified DSLR camera shooting daylight white balance. The camera's color response closely resembles the color sensitivity of the human eye, so the colors seen here are close to being correct. This should be what the color of the nebula looks like visually through a large telescope to a person with normal color vision, although you probably would not see quite this much color saturation. Image Data
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