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 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 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 shrink, surviving sungrazers collide with the sun on a subsequent passage.

Ikeyaseki
© NOAOComet Ikeya-Seki
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.

Because the sungrazers are so short-lived, they must have come from parent bodies that broke apart. In fact the majority belong to a hypothesized "mother comet" that split apart perhaps as long as 2000 years ago. The fragments whip around the sun as gravitational perturbations nudge the low point (perihelion) of their elliptical orbits closer to the sun.

Nostradamus and Mayan calendar 2012 sooth-says will likely see this as yet another omen of their predicted "end of times." A lot of their websites talk about a "killer comet" coming. Maybe this is just the first assault wave. (BTW, for you UFO folks the bright spot at lower right is not one of many alleged spaceships near the sun, but the planet Mercury.)

In reality sungrazing comets are common. Most are too small to see but occasionally a big fragment attract attention. The solar system is a very cluttered and dynamic place to live, even 4 billion years after its baptism by fire.