At first glance it looks like aliens are using the sun for target practice.

A string of bullet-shaped streaks of light appear to be shooting straight toward the sun.

These are the proverbial snowballs in Hell, plunging 300 miles per second toward a fiery end in the sun’s atmosphere.

The NASA/ESA Solar and Heliospheric Observatory (SOHO) observed the demise of one comet fragment on Friday, March 12.

The wayward comets are called sungrazers. They are a class of comet that likes to live dangerously. Sungrazers can skirt within a few thousand miles of the sun’s roiling photosphere. Many are torn apart or evaporate as they streak along at a blazing 1 million miles per hour. As their orbits are perturbed, surviving sungrazers can collide with the sun on a subsequent passage.

The first recognized sungrazing comet was detected during a total solar eclipse in May 1882. Just imagine the surprise and awe as a glowing streak of light appeared to observers as the sun entered totality. Other sungrazers have been briefly bright enough to be seen in the daytime sky alongside the sun. The most recent, comet Ikeya-Seki in 1965.

Once solar observing satellites were lofted into orbit the sungrazers were easily detected. SOHO, with its coronographs, has cataloged over 1,000 sungrazers in spectacular passages.

But we missed the real fireworks by 4 billion years. The period of late heavy bombardment in the newborn solar system should have seen the sky around the sun ablaze with sungrazers.

Evidence comes from observations of the young Beta Pictoris system that is believed to have recently formed planets. Since the early 1990s astronomers have monitored transient events in the star’s visible spectrum that are interpreted as resulting from evaporating comets skirting Beta Pictoris.

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It’s very easy to get worried when you hear that a star could explode “with the force of 20 billion billion billion megatons of TNT” and the explosion is going to detonate so close to us that it “could strip away the Earth’s ozone layer.”

However, when the news source also states this supernova could happen “soon,” we suddenly have an imminent doomsday event in the offing! Stock your lead-lined bunker now! Buy as many cans of baked beans as you can carry!

As with many astronomical meetings, the American Astronomical Society (AAS) conference currently underway in Washington D.C. is presenting some astonishing, cutting-edge research from the world’s best scientists. However, often this research can sound a bit scary. For example, the energies associated with supernovae and gamma-ray bursts will do more than simply singe your eyebrows off, these events can decimate entire star systems.

Enter the U.K.’s Telegraph, with an article entitled, “Earth ‘to be wiped out’ by supernova explosion.” One would think that by making such a statement, the journalist must have found a fairly compelling piece of evidence that suggests global doom?

Not so much.

The article is referring to research presented at the AAS by Edward M. Sion and his team from Villanova University, Philadelphia. Their research suggests that a binary star called T Pyxidis is acting rather strange.

Up until 1967, T Pyxidis was exploding as a recurrent nova every 20 years or so. This nova was being caused by a white dwarf sucking gas from its companion star. As the quantity of gas reached a certain limit, it would detonate as a nova (a stellar explosion that leaves the star intact). However, for the last 40 years, the repeating novae have stopped.

Naturally, this excites astronomers and Sion’s team has reached the conclusion that T Pyxidis is about to go supernova (in this case, it would be a Type 1a supernova, destroying both stars).

This fact alone was the trigger for the Telegraph’s scary headline (although it’s not clear where the quote ‘to be wiped out’ came from — damage to the ozone layer is one thing, wiping out Earth is quite another!).

Interested in what was going on, I contacted my colleague Ray Villard who is currently attending the conference in D.C. and he confirmed that the Telegraph article is 90 percent hype.

During Sion’s presentation, he was challenged by one of his peers in the audience, Prof. Alex Fillipenko from Berkeley Astronomy Department. Apparently Sion had possibly miscalculated the damage that could be caused by a T Pyxidis supernova.

It seems that Sion had used data for a far more deadly gamma-ray burst (GRB) exploding 3,260 light-years from Earth, not a supernova. T Pyxidis certainly isn’t expected to produce a GRB. (Gamma-ray bursts are thought to only be generated by a massive star that has reached the end of its life as a Wolf-Rayet star collapsing under its own gravitational attraction.)

“A supernova would have to be 10 times closer [to Earth] to do the damage described,” Ray informed me via email.

The scientists at the meeting were also highly dubious about Sion’s estimate that the star could explode imminently. In fact, the Telegraph article even closes with a quote from Robin Scagell, vice-president of the UK’s Society for Popular Astronomy: “The star may certainly became a supernova soon — but soon could still be a long way off so don’t have nightmares.”

In summary, T Pyxidis is too far away to cause the Earth any harm and there’s doubt that the star will even explode “soon.”

So, where’s the panic? That’s right, there isn’t any. I’m sure the Telegraph took Sion’s pre-conference press release at face-value and didn’t have the good fortune to have a correspondent at the AAS to confirm Sion’s claims. But, publishing an article indicating a global catastrophe is imminent strikes me as a little irresponsible.

Meetings like the AAS are key to the scientific process where theories are aired and results are open to academic scrutiny, sometimes it’s better to wait until after the conference before reaching any conclusions.

For almost two centuries, humans have looked up at a bright star called Epsilon Aurigae and watched with their own eyes as it seemed to disappear into the night sky, slowly fading before coming back to life again. Today, as another dimming of the system is underway, mysteries about the star persist. Though astronomers know that Epsilon Aurigae is eclipsed by a dark companion object every 27 years, the nature of both the star and object has remained unclear.

Now, new observations from NASA’s Spitzer Space Telescope — in combination with archived ultraviolet, visible and other infrared data — point to one of two competing theories, and a likely solution to this age-old puzzle. One theory holds that the bright star is a massive supergiant, periodically eclipsed by two tight-knit stars inside a swirling, dusty disk. The second theory holds that the bright star is in fact a dying star with a lot less mass, periodically eclipsed by just a single star inside a disk. The Spitzer data strongly support the latter scenario.

“We’ve really shifted the balance of the two competing theories,” said Donald Hoard of NASA’s Spitzer Science Center at the California Institute of Technology in Pasadena. “Now we can get busy working out all the details.” Hoard presented the results today at the 215th meeting of the American Astronomical Meeting in Washington.

Epsilon Aurigae can be seen at night from the northern hemisphere with the naked eye, even in some urban areas. Last August, it began its roughly two-year dimming, an event that happens like clockwork every 27.1 years and results in the star fading in brightness by one-half. Professional and amateur astronomers around the globe are watching, and the International Year of Astronomy 2009 marked the eclipse as a flagship “citizen science” event. More information is at http://www.citizensky.org.

Astronomers study these eclipsing binary events to learn more about the evolution of stars. Because one star passes in front of another, additional information can be gleaned about the nature of the stars. In the case of Epsilon Aurigae, what could have been a simple calculation has instead left astronomers endlessly scratching their heads. Certain aspects of the event, for example the duration of the eclipse, and the presence of “wiggles” in the brightness of the system during the eclipse, have not fit nicely into models. Theories have been put forth to explain what’s going on, some quite elaborate, but none with a perfect fit.

The main stumper is the nature of the naked-eye star — the one that dims and brightens. Its spectral features indicate that it’s a monstrous star, called an F supergiant, with 20 times the mass, and up to 300 times the diameter, of our sun. But, in order for this theory to be true, astronomers had to come up with elaborate scenarios to make sense of the eclipse observations. They said that the eclipsing, companion star must actually be two so-called B stars surrounded by an orbiting disk of dusty debris. And some scenarios were even more exotic, calling for black holes and massive planets.

A competing theory proposed that the bright star was actually a less massive, dying star. But this model had holes too. There was no simple solution.

Hoard became interested in the problem from a technological standpoint. He wanted to see if Spitzer, whose delicate infrared arrays are too sensitive to observe the bright star directly, could be coaxed to observe it using a clever trick. “We pointed the star at the corner of four of Spitzer’s pixels, instead of directly at one, to effectively reduce its sensitivity.” What’s more, the observation used exposures lasting only one-hundredth of a second — the fastest that images can be obtained by Spitzer.

The resulting information, in combination with past Spitzer observations, represents the most complete infrared data set for the star to date. They confirm the presence of the companion star’s disk, without a doubt, and establish the particle sizes as being relatively large like gravel rather than like fine dust.

But Hoard and his colleagues were most excited about nailing down the radius of the disk to approximately four times the distance between Earth and the sun. This enabled the team to create a multi-wavelength model that explained all the features of the system. If they assumed the F star was actually a much less massive, dying star, and they also assumed that the eclipsing object was a single B star embedded in the dusty disk, everything snapped together.

“It was amazing how everything fell into place so neatly,” said Steve Howell of the National Optical Astronomy Observatory in Tucson, Ariz. “All the features of this system are interlinked, so if you tinker with one, you have to change another. It’s been hard to get everything to fall together perfectly until now.”

According to the astronomers, there are still many more details to figure out. The ongoing observations of the current eclipse should provide the final clues needed to put this mystery of the night sky to rest.