The particular image featured here, showing what appears to be a large ribbon of gas floating through our galaxy, shows in fact only a small section of a much larger circular structure originating from a supernova explosion that took place somewhere in the spring of 1006 A.D., dubbed SN 1006. The progenitor star, a white dwarf, would have to been located about 7,000 light years away, while the optical emissions generated by the explosion would have been bright enough to be visible in broad daylight for several weeks in a row.

It is estimated that the bright emission of light remained visible on the night sky for as much as two and a half years before fading enough to evade the detection of the naked eye. Its remnant was discovered by radio astronomers some four decades ago in the form of a circular feature measuring about the same angular diameter as the Moon. Considering its size, distance and current rate of expansion, astronomers approximated that the explosion must have taken place about 1,000 years ago.

The portion of the ribbon recently pictured by Hubble raised interest in 1976 when it was found to emit a faint optical signature, probably as a result of colliding with interstellar clouds of gas and dust. As this happens, the hydrogen gas of the remnant glows in visible light to reveal some of the most intricate details regarding its current position and geometry.

The circular remnant of the supernova explosion measures about 60-light years across and is still expanding into space at a staggering 9.6 million kilometers per hour. As it is seen in the image taken by Hubble, the position of the progenitor star would have had to be far down and to the right of the image, thus expanding towards the upper left corner.

Since it sits 14 degrees above the galactic plane, there is little room for confusion with other background stars or galaxies. As you can see here, the reddish objects are galaxies while the white spots are stars located within our own galaxy. The visible hydrogen emissions given off by the remnant have been depicted in a red hue for better observation.