The supernova RCW 86 lit up the sky for eight months, documented at the time as a "guest star". In more recent times, astronomers have wondered how it grew so large, so fast. Space telescope observations now suggest that before exploding, a wind of material from the star blew a cavity around it, into which the supernova could expand much more quickly. The supernova, about 8,000 light-years away, is huge - if the infrared light it emits could be seen by our eyes, it would appear to be as large in the sky as the full Moon. The findings, published in the Astrophysical Journal, combine existing data from the Chandra X-ray telescope and the XMM-Newton Observatory with recent images from the US space agency Nasa's Spitzer and Wide-field Infrared Survey (Wise) telescopes. Read more: http://www.bbc.co.uk/news/science-environment-15445688
It is always mind blowing to ponder the size of the universe. One light year is approximately 6 trillion miles. The supernova is 8,000 light years away. Also consider the fact that what we are observing now is light that left its source 8,000 years ago.
Yeah, the sky is a time machine. We are looking back in time by enormous time periods. 8000 light years is really close. The milky way is 100,000 light years across, and it's just one of a gazillion galaxies. On a side note, if every dollar of the national debt were a mile, the debt would stretch more than half way to the nearest star, which is ~4 light years away.
