Incredible comet ISON explosion set to hijack turkey day

Incredible comet ISON explosion set to hijack turkey day

Comet ISON is on a "sungrazing" course for Earth's nearest star. If it survives, it could become one of the most brilliant visible comets in modern history.

If there’s one thing most Americans remember from grade school history classes, it’s the Thanksgiving tradition: Every year, on the fourth Thursday in November, families travel distances great and small to reunite and celebrate rare, possibly spectacular cosmic events (and something about turkey). At least, that’s the theme of this year’s celebration, as the comet ISON hurtles towards the sun and its potential cataclysmic demise.

Comets are essentially large space rocks that have accumulated a covering of snow and dust, resulting in the visible “tails” with which we closely associate them. ISON, which has been visible by telescope for weeks, is on a course for our sun and will reach perihelion (its closest point to the sun) on November 28, just in time for the green bean casserole. As for what happens after that, scientists are unsure. One possibility is that as ISON attempts to slingshot around the sun, exposure to massive amounts of solar radiation could simply destroy it. If it remains intact, it could go on record as one of the brightest comets ever as it passes by Earth again on its way out of the solar system.

A similar event happened in 2007, when comet Encke was struck by a CME (coronal mass ejection). CMEs are magnetized clouds of plasma hurled into space by the explosions of sunspots.  The gas inside a CME is not very dense, so its impact would not shatter a comet’s core. The fragile tail is another matter. Comet tails are as gossamer as the CMEs themselves, so the interactions can be intense and unpredictable. The impact was so powerful that Encke’s tail was separated from the head, though the comet remained intact. That’s what could happen to ISON, though according to NASA conditions are right for ISON’s perihelion to be even more spectacular.

“For one thing,” says Angelos Vourlidas of the Naval Research Lab and a participant in NASA’s Comet ISON Observing Campaign (CIOC), “the year 2007 was near solar minimum. Solar activity was low. Now, however, we are near the peak of the solar cycle and eruptions are more frequent.”

Vourlidas notes that the CME that struck Encke in 2007 was “slow, barely creating a pressure pulse by compressing the solar wind ahead of it.” ISON might not be so lucky, were it to encounter a CME itself. According to Vourlidas, “Any CME that hits Comet ISON close to the sun would very likely be faster, driving a shock wave with a much stronger magnetic field.  Frankly, we can’t predict what would happen.”

Be social, please share!

Facebooktwittergoogle_plusredditpinterestlinkedintumblrmail

Leave a Reply

Your email address will not be published. Required fields are marked *