(Image source: Science News)

BY RYAN SCHMIDT

ANCHOR ANA COMPAIN-ROMERO

Almost a year after a giant star exploded in the stratosphere -- Christmas Day 2010 -- scientists think they know what caused it.  

Two teams of scientists have developed theories about what caused the explosion, and where it happened.  

The problem is, both teams think they’re right.

First -- some background. NASA’s Swift Observatory caught the explosion on Christmas Day 2010. It lasted some 28 minutes, which according to Science Daily is “unusually long.” At the time though, observers couldn’t figure out how far away it occurred or what really happened.

Now -- two separate groups say they have the answer. One, a team from Spain, says it happened 5.5 billion light years away -- whereas the other says it was in our galaxy. Cosmos Magazine explains:

“...one involves a kamikaze comet; the other involves an exotic star merger. [The latter suggests] … these stars merged to form either a black hole or magnetised neutron star, creating a supernova and an associated [gamma ray burst] event.”

Gamma ray bursts, according to Science Daily, are explosions that put out more energy than the sun. But the other team, a group of Italian astronomers, says it actually wasn’t a gamma ray burst.

“This involves the tidal disruption of a large comet-like object and the ensuing crash of debris onto a neutron star located only about 10,000 light-years away.”

So what to do with two such radically different theories? First, Science Daily looks at what the teams DO agree on.

“Common to both scenarios is the presence of a neutron star, the crushed core that forms when a star many times the sun's mass explodes. When the star's fuel is exhausted, it collapses under its own weight, compressing its core so much that about a half-million times Earth's mass is squeezed into a sphere no larger than a city.”

National Geographic reports both theories leave unanswered questions about the burst, but it quotes an Italian astrophysicist who leans more toward the kamikaze comet theory.

“We could compute the likelihood of each hypothesis, and perhaps discard one on the basis of statistical considerations. ...The odds are that the event is a rare phenomenon that looks like a GRB but falls outside this category.”

Finally -- as if your head’s not spinning enough -- Science News doesn’t take sides but rather throws out an entirely new possibility.

“While scientists might quibble over which scenario best fits the data, most agree that unambiguously resolving where the burst occurred will point toward one explanation or the other. Of course, the burst could still be the product of an even more exotic event, says [astrophysicist Enrico] Ramirez-Ruiz. ‘I think this object is unique enough that is could certainly be attributed to something we haven’t thought of.’”

CNN reports both hypotheses need more evidence to disprove each other.  The complete article appears in this month’s issue of Nature.