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sunset comet

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presented by science at nasa

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for a comet visiting the sun is risky

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business

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fierce solar radiation vaporizes gases

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long frozen in the fragile nucleus

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breaking up some comets and completely

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destroying others

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that's why astronomers weren't sure what

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would happen in early march when comet

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panstarrs a first-time visitor to the

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inner solar system dipped inside the

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orbit of mercury on march 10th nasa's

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stereo b spacecraft watched as the comet

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made its closest approach to the sun

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only 28 million miles away

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at that distance the sun loomed three

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times wider and felt more than 10 times

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hotter than it does on earth

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this just in the comet survived

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still intact comet pan stars is emerging

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from the sun's glare into the sunset

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skies of the northern hemisphere

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solar heating has caused the comet to

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glow like a star of second magnitude as

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bright as the stars of the big dipper

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bright twilight reduces visibility but

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it is still an easy target for

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binoculars and small telescopes one to

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two hours after sunset

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discovered in june 2011 by astronomers

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using the pan-starr survey telescope

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atop the haleakala volcano in hawaii the

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comet is paying its first visit to the

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inner solar system

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it hails from the oort cloud

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a deep space reservoir of comets far

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beyond the orbit of pluto

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because comet pan stars is a newcomer

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astronomers didn't know what to expect

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now they know

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it is a gorgeous comet one of the

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brightest in years says astronomer

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matthew knight of the lowell observatory

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comet specialist emmanuel yahin of the

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european southern observatory has been

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monitoring comet pan stars using a

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remote controlled telescope in chile

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based on his data knight concludes that

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comet panstar seems to be producing

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quite a bit of dust compared to an

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average comet

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this is very good for its visibility

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because the extra dust is reflecting

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sunlight and making comet pan stars

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appear brighter than it would otherwise

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the amount of dust and gas spewing from

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the comet implies a nucleus on the order

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of one kilometer in diameter in other

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words neither unusually large nor small

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size-wise it is a fairly typical comet

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the comet's tail is anything but typical

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stereo b images processed by carl

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battams of the naval research lab in

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washington dc reveal many wild and

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ragged striations in the cloud of dust

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trailing behind comet pen stars

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wow says badams the fine structure is

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breathtaking we're not sure what causes

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this

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possibilities include irregular

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outgassing in the comet's core

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fragmentation events and interactions

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with the gusty solar wind

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the comet is now receding from earth it

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will slowly dim as it heads back into

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deep space

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ironically though its visibility will

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improve for a while as it heads into

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darker skies away from the sun

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it might even become a naked eye object

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in the closing weeks of march

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step outside after sunset face west and

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take a look