Side-by-side images show the constellation Orion in visible (left) and infrared light. The infrared comes from clouds of gas and dust, some of which are collapsing to give birth to new stars. The most prominent example is the Orion Nebula, which is a small pink smudge below Orion's Belt in the visible image, but a bright, massive blob in the infrared. By contrast, most of the stars that appear bright at visible wavelengths don't show up in the infrared. The only major exception is Betelgeuse, at the top left corner, which emits most of its energy as red or infrared light. The infrared view came from IRAS, the first infrared space observatory, which was launched in January 1983. Subsequent infrared observatories have provided far sharper views of Orion and many other star-forming regions. [NASA]
The human eye is finely tuned to see a narrow range of wavelengths — a range of colors from deep red to deep blue. Yet there’s an entire universe beyond those extremes — from wavelengths that are just a thousandth as long as the eye can see, to wavelengths that are a million times longer.
The longer side begins with the infrared. It’s produced by some of the coolest objects in the universe — objects like clouds of gas and dust that are giving birth to new stars. But they’re difficult to study from Earth’s surface because the atmosphere absorbs most infrared energy.
The first major attempt to extend our view into the infrared began 30 years ago today, with the launch of IRAS — the Infrared Astronomy Satellite.
When it was launched, astronomers had discovered about 250,000 objects in the infrared. During its 10 months of operation, IRAS doubled that number. It also provided details on those objects that were impossible to see from the ground — details like temperature and composition. And it provided the most detailed pictures of these objects, allowing us to see their structure.
IRAS studied newborn stars, disks of gas and dust that are giving birth to planets, dusty galaxies, and icy comets. Those observations helped astronomers learn more about how stars and planets are born, and how galaxies evolve — new knowledge made possible by extending our vision into a new realm.
Script by Damond Benningfield, Copyright 2012
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