In the spring of the year 1006, Earth's sky was drastically altered by the appearance of a supernova that was brighter than the entire combined night sky. Mentioned in historical records throughout Europe, Asia, Africa, and North America, this supernova was likely bright enough to be visible during daylight hours, with some accounts even claiming it cast its own shadows. Now, 1007 years later, this exploded star doesn't look quite so impressive.
This supernova remnant was first identified as the 1006 object back in 1965. While these remnants belong to what was briefly the most impressive guest star in human history, second only in relative brightness to our own Sun, these days the remains are mostly visible only in the X-ray spectrum. A NASA astronomer explains:
The expanding debris cloud from the stellar explosion, found in the southerly constellation the Wolf (Lupus), still puts on a cosmic light show across the electromagnetic spectrum. In fact, the above image results from three colors of X-rays taken by the orbiting Chandra X-ray Observatory. Now known as the SN 1006 supernova remnant, the debris cloud appears to be about 60 light-years across and is understood to represent the remains of a white dwarf star. Part of a binary star system, the compact white dwarf gradually captured material from its companion star. The buildup in mass finally triggered a thermonuclear explosion that destroyed the dwarf star. Because the distance to the supernova remnant is about 7,000 light-years, that explosion actually happened 7,000 years before the light reached Earth in 1006. Shockwaves in the remnant accelerate particles to extreme energies and are thought to be a source of the mysterious cosmic rays.
For more information, not to mention lots of other amazing images from the depths of space, check out NASA's Astronomy Photo of the Day.
Image credit: NASA/CXC/P. Frank Winkler (Middlebury College)