The Orion Nebula
© Sonya Thomas-Haley
The sword of Orion is defined by the bright M42 and the nearby smaller M43. This is the cradle of newborn stars, and at its heart is Theta Orionis, more popularly known as the Trapezium.
Theta is a quadruple star. The four stars are arranged like a trapezoid and are very easily spotted in the heart of the ghostly glow. They are the driving force behind this nebula; it is largely their radiation that makes this enormous cloud of gas fluoresce.
But they are just the brightest of a cluster of some 700 stars. This cluster is expanding; and, based on studies of the expansion rate, it appears this cluster may be a mere million years old. On the cosmic scale, that's practically yesterday.
Because of this extreme youth, the Great Orion Nebula has been a prime target for the Hubble Space Telescope in an effort to capture stars in the very earliest stages of formation and, as an added bonus, perhaps capture the earliest stages of planetary formation. That is exactly what Hubble has found.
Around many stars in the Orion Nebula, Hubble has found protoplanetary discs. Scientists have condensed this term to "proplyds" (which to me sounds more like some exotic skin disease, but, then, scientists do seem to have a knack for non-poetic names). It appears that proplyds are very common in the Orion Nebula and that may be an indication that planetary systems are very common in the universe.
On the other hand, the incredible amount of radiation blasting away from the Trapezium appears to also be blasting away some of these discs. These discs appear dark because of the light-absorbing dust eventually destined (if given the chance) to form planets. Here is an image of a disc seen edge-on, the dust obscuring the glow of the central star. An eerie image -- a glimpse, perhaps, into our own past.
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