A Nearby Death Star - Eta Carinae?
Keep your brain active by pondering this scenario. In the U.S., our greatest risk of catastrophic natural disaster is probably the Yellowstone caldera, which is a gigantic simmering volcano capable of ending life in the western U.S. and changing weather worldwide for a number of years, possibly launching an ice age. It is highly active, as in recent years geysers have been changing their flow patterns on an accelerated pace - old Faithful is less faithful and less impressive, but other even larger geysers once dormant have become increasingly active. Apparently there is no immediate threat, however.
In the skies, people like Stephen Hawking and Arthur C. Clarke have been calling for mankind to colonize space, not merely for vanity's sake but as a matter of species survival. People speculate about rogue asteroids or comets impacting earth and creating a vision of destruction and flames in the atmosphere - but an asteroid may not be the only risk, and the timing might be more urgent than is commonly perceived.
Relatively close to the solar system at 7,500 light years away is a giant, unpredictable star. This star, Eta Carinae, is 100 times more massive than the sun and more than 4,000,000 times brighter. For a while in the 19th century it was the second brightest star in the sky. Astronomers have known about the star for some time. In the year 2000 it also showed strange perturbances. By 2007, it has started growing brighter again.
The estimated age of Eta Carinae is around 300,000 years (extremely young). However, the lifespan of a star this massive is 1 million years or less. This means that at anytime, from now to a few hundred thousand years in the future, Eta Carinae will explode in a giant supernova so large it is called a hypernova.
Quite possibly this has already occurred - with our linear view of time we would not know for 7,500 years - the rapid changes in the star visible in just over two centuries from our Earth vantage point might be compared to watching the lit fuse on a time bomb.
The intense gamma ray radiation burst from Eta Carinae will be strong enough to at least damage satellites and could possibly end all life on earth - no one really knows. If earth and the atmosphere are shielded from the gamma ray burst and shockwave accompanying the overwhelming visual light, which may be brighter than all of the stars of the Milky Way Galaxy for a short duration, possibly all will be well. However, this outcome is unknown. Otherwise, the atmosphere could be set aflame, with a proliferation of nitric oxides, radioactive Carbon 14, and total loss of ozone - the sun's radiation would hit the earth with full force. This is "An Inconvenient Truth" on a cosmic scale. Comforted as we are by the stability of the sun, which will not reach red giant size for about 5 billion years, Eta Carinae has evolved in a cosmic blink of an eye and it is capable of ending life just as quickly. Conversely, through their destruction, supernovas also replenish heavy elements necessary for life as stardust scattered by the shockwave. If you happen to read this message, please pass it on or post it to encourage debate, discussion is the first step to awareness, followed by solutions.