Published On: Tue, Nov 26th, 2013

Close encounter with the sun

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Don’t look now, but the comet of the century has been on a near collision course with our sun.

Yes, yes, I know we have all heard that before and then been disappointed with results, but the jury is still out on this one.

Known as ISON or sometimes as C/2012 S1, it was discovered in September of last year by a couple of Russian amateur astronomers.

Attracted by the sun’s gravity, this visitor from the great Oort cloud has been traveling quickly and getting brighter as it got closer.  The nucleus or main body of the comet is only about a mile across, but it pours out gases that expand and reflect light.  The coma that it creates is much larger than earth.

Bob Anderson, engineer at the NRAO, was able to see the comet but he said it wasn’t easy to pick it out of the sun’s glare on the horizon.  Only at daybreak, right there next to Mercury and with Saturn way off in the background, Comet ISON did finally yield some nice views.

As it rushes head on for its anticipated rendezvous, it will pass within about 700,000 miles of the surface of the sun and may brighten significantly.  The heat and stress will be huge on this dirty snowball of water and different frozen gases and it may – possibly – be visible in the daytime.

On Thanksgiving Day just after noon, the comet takes its quick turn around the sun, then slingshots off in a new direction.  To see this phenomenon don’t look directly at the sun.  Block the sun with a utility pole or chimney or some other tall, solid object.  The comet may appear there beside the sun.  This is a decidedly low tech approach but the sun’s glare can be dangerous to the eyes.  And don’t use binoculars or sunglasses as they will not provide enough protection for a direct look.

So, is anybody at the NRAO observing this marvel?  You bet they are.

Amy Lovell is a Professor of Physics and Astronomy at Agnes Scott College in Decatur, Georgia, and has a special interest in comets and asteroids.  She has observed several comets using the Robert C Byrd Green Bank Telescope and is particularly interested in the spectral line observations of the hydroxyl unit, the OH radical being two-thirds of a water molecule and very reactive.  Any new comets coming along, you can be sure that Amy will be there to check them out.

Another observer is Tony Remijan, an NRAO scientist from Charlottesville, Virginia.  His team, of mostly NASA scientists, is interested in chemistry and compounds and they employ a multi-wavelength approach that may use several different receivers on the GBT.

So, what happens after Thanksgiving Day?

Knowing the speed and size of the comet and the probable forces of the sun’s gravity, a projected pathway can be calculated and should send the comet ISON higher in the north sky.  In fact late in the month of December, it will be passing by Polaris, the North Star.  As such it will be visible all night long, except that it will be getting further away and more difficult to see.

Is this the Comet of the Century?

Too early to tell.  The great comet of 1680 was one of the all time brightest.  And its most brilliant spell was about 30 days after circling the sun.

Could that happen to ISON?

Maybe.

On the other hand, ISON could totally disintegrate due to the forces and heat of the sun.  Much like Phaethon, the son of Helios, who attempt to drive the sun chariot across sky, then crashed and burned as the chariot went out of control, ISON could end up as a few scattered pieces.

Stay tuned.

We should all learn something in the next week or two.  And for all of you hunters, loggers and anyone out there in the pre-dawn hours, keep an eye on that horizon and you may discover a real miracle.

Dave is a telescope operator at the NRAO and can be contacted at davecurry51@gmail.com.

 

 

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