English: Chandra close-up of a full-field, deep image of the Orion Nebula Cluster (M42), a rich cluster approximately 1500 ly from Earth containing over 1600 X-ray sources. About 1,400 of these are young stars in the Orion Nebula. The rest are either background galaxies or foreground stars. The observation period (of 233 hours total) was done during 6 pointings between January 8 and January 21, 2003 with Chandra's Advanced CCD Imaging Spectrometer (ACIS). The image is 5.5 arcmin across, covering about 2.5 ly on a side. Colors represent different energy ranges: Red 0.3-1.0 keV, Green 1.0-3.0 keV and Blue 3.0-8.0 keV. Variations in the amount of gas along the line of sight filters out different amounts of X-rays resulting in different colors. The red X-ray sources are mostly young stars in the Orion Nebula with little absorption by intervening gas and the blue X-ray sources are mostly young stars with larger amounts of gas absorption. The luminous source in the middle of the cluster, Theta Orion Nebulais C, is the brightest and most massive star in the cluster at 33 solar masses and a luminosity of 204,000 solar luminosities. Young (1 to 10 million year old) stars in the cluster produce violent X-ray outbursts, or flares, that are much more frequent and energetic than present-day flares from our 4.6 billion-year-old Sun. It has been suggested that the Sun produced more violent, energetic X-ray flares earlier in its life.