21Dec2011

No Doomsday Supernova Next Week

Really? There are people out there who predict — with an unbelievable degree of accuracy — that 21 December 2012 will herald a rare stellar explosion that will wipe out (or at least cripple) life on Earth? (Why the hell it had to be on my birthday I don't know! Ed.)

Well, if my email inbox is anything to go by, then yes, I'm sure this little doomsday scenario is doing the rounds. And by the sound of things, NASA is also getting fed up with messages from individuals needlessly worrying about a star that's about to go "BOOM!"

In an impromptu public space service announcement from the U.S. space agency on Friday, Francis Reddy, of NASA's Goddard Spaceflight Center, went on the record to say: "…astronomers can say with certainty that there is no threatening star close enough to hurt Earth."

As if the world didn't have enough doomsday scenarios to worry about — like nonsensical killer solar flares, non-existent Planet X's, silly geomagnetic reversals, insane pole shifts and hordes of kamikaze lemmings* — doomsayers are apparently circulating the myth that a star is soon to go gangbusters this time next year. Wow.
invisible soldier

But before you rush to Barnes & Noble to buy the next crappy "Doomsday in 2012" book and put your house up for sale, take a hint: You are being conned! "Astronomers estimate that, on average, about one or two supernovae explode each century in our galaxy," says Reddy. "But for Earth's ozone layer to experience damage from a supernova, the blast must occur less than 50 light-years away."

Guess what? The nearest star likely to go supernova any time soon is much further than 50 light-years away. Also, the galaxy is a very big place, so the odds of any stellar dramatics even remotely close to the solar system in the next 12 months is vanishingly small.

Reddy goes into some of the details as to how a supernova could cause damage to the Earth's atmosphere and the life therein — because, let's face it, a star's core collapse would be bad news if it were in our cosmic backyard — but as there's no dying stars around, why be concerned?

What about a gamma-ray burst, the supernova's big bad cousin?

As a massive star runs out of fuel and collapses, sometimes it may form a black hole. These massive dying stars are called Wolf-Rayet (WR) stars, my favorite stellar objects. If the conditions are right, it is thought that as a WR star collapses and stellar material starts to fall into the newborn singularity, powerful jets of radiation will blast from the exploding star's poles.

Should Earth be in the line-of-sight of one of these bad boys then, well, bad news for us. Probably the most scary thing about GRBs is their range. Should Earth be caught in the cross-hairs of a GRB, its radiation would hurt us even if the star was 10,000 light-years distant.

Fortunately, these kinds of local events happen approximately every 15 million years or so, and the nearest gamma-ray burst on record occurred a rather remote 1.3 billion light-years away. So where are the doomsayers getting their information from if the science (and statistics) is telling us that a nearby supernova or GRB isn't expected any time soon?

Well, in the effort to build the fear-factor for the impending end of the Mayan "Long Count" calendar (plus an unhealthy dose of superstition and conspiracy), 2012ers are busy trying to sell their personal versions of doom. Oddly enough, most doomsayers have a book to sell or website to advertise, so I won't be getting my doomsday "science" from those wingnuts.Source: Discovery News

 

Fear Not A Supernova 2012

Here's another variation of the above article:  Given the incredible amounts of energy in a supernova explosion – as much as the Sun creates during its entire lifetime – another erroneous doomsday theory is that such an explosion could happen in 2012 and harm life on Earth. However, given the vastness of space and the long times between supernovae, astronomers can say with certainty that there is no threatening star close enough to hurt Earth.

Astronomers estimate that, on average, about one or two supernovae explode each century in our galaxy. But for Earth's ozone layer to experience damage from a supernova, the blast must occur less than 50 light-years away. All of the nearby stars capable of going supernova are much farther than this.

Any planet with life on it near a star that goes supernova would indeed experience problems. X- and gamma-ray radiation from the supernova could damage the ozone layer, which protects us from harmful ultraviolet light in the sun's rays. The less ozone there is, the more UV light reaches the surface. At some wavelengths, just a 10 percent increase in ground-level UV can be lethal to some organisms, including phytoplankton near the ocean surface.

Because these organisms form the basis of oxygen production on Earth and the marine food chain, any significant disruption to them could cascade into a planet-wide problem. Another explosive event, called a gamma-ray burst (GRB), is often associated with supernovae. When a massive star collapses on itself – or, less frequently, when two compact neutron stars collide – the result is the birth of a black hole.

As matter falls toward a nascent black hole, some of it becomes accelerated into a particle jet so powerful that it can drill its way completely through the star before the star's outermost layers even have begun to collapse. If one of the jets happens to be directed toward Earth, orbiting satellites detect a burst of highly energetic gamma rays somewhere in the sky. These bursts occur almost daily and are so powerful that they can be seen across billions of light-years.

A gamma-ray burst could affect Earth in much the same way as a supernova – and at much greater distance – but only if its jet is directly pointed our way. Astronomers estimate that a gamma-ray burst could affect Earth from up to 10,000 light-years away with each separated by about 15 million years, on average. So far, the closest burst on record, known as GRB 031203, was 1.3 billion light-years away.

As with impacts, our planet likely has already experienced such events over its long history, but there's no reason to expect a gamma-ray burst in our galaxy to occur in the near future, much less in December 2012.  Source: Space Daily

Related stories

ANALYSIS: Will Earth 'Be Wiped Out' by a Supernova?

SLIDE SHOW: Top 5 REAL Cosmic Doomsday Events of 2011

 

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