Updated (above) with this morning’s clear view of Comet Lovejoy over WA Pilots and passengers have reported the appearance of a great comet in the pre dawn skies from flights between Perth and the eastern cities this morning. The ghostly crescent tail, rising like a searchlight above the eastern horizon, is that of Comet Lovejoy, […]

Updated (above) with this morning’s clear view of Comet Lovejoy over WA

Pilots and passengers have reported the appearance of a great comet in the pre dawn skies from flights between Perth and the eastern cities this morning.

The ghostly crescent tail, rising like a searchlight above the eastern horizon, is that of Comet Lovejoy, and if skies clear over eastern Australian skies in coming mornings, the comet is likely to be easily observed by early risers, as it has been in the dark northern hemisphere skies by millions of surprised commuters.

Comet Lovejoy will be easy to see from almost anywhere in the world except extreme southern and northern latitudes in the following days if the skies clear.

Named after Australian astronomer Terry Lovejoy who discovered it on 2 December it may well become the Great Christmas Comet of 2011 if it continues to perform until Sunday morning. It is has already surprised millions of pre dawn travellers in the northern hemisphere where the sun doesn’t rise until much later in the morning in wintery skies.

Comet Lovejoy is the third great comet since the October 1965 appearance of Ikeya-Seki and Comet McNaught in January and February of 2007. The term ‘great’ comet has been used subjectively in the literature whenever one of them is especially visible.

Halley’s Comet was a ‘great’ comet in 1910, but not in 1986, when it followed a more distant and thus fainter trajectory as seen from the earth.

Like Ikeya-Seki in 1965, Comet Lovejoy is believed to be a large fragment of a gigantic comet that broke up in the inner solar system in 1106, forming a cloud of debris that became known as the Kreutz family of sungrazer comets.

Kreutz sungrazers are commonly detected by sun observing satellites and telescopes plunging close to the solar disk and being evaporated by the intensity of the approach. Most of them are believed to be only a few metres across, and unable to withstand the ferocious heat of a close encounter with the sun.

However like Ikeya-Seki in 1965 the solid nucleus of Comet Lovejoy is believed to be hundreds of metres across, and large enough to survive the close passage even while huge amounts of frozen gases and dust were blasted off its surface or driven out of its substructure to create the spectacle of a great comet as it heads back to the outer solar system and beyond.

(Ikeya-Seki was seen to break apart in 1966 as it receded from the sun.)

Kreutz class sungrazers are highly unpredictable in their behavior. Comet Loveyjoy might completely disintegrate into a brief dazzling display, or just fade to black in coming days or weeks.

Amateur astronomer photos like that taken by Colin Legg in Mandurah near Perth this morning (above) are being posted on Space Weather, together with sky maps that are updated to show the comets location in the same part of the sky as the moon, which is becoming a crescent pre dawn moon in the coming days, and bright stars and visible planets.

Legg has also posted a time lapse set of wide sky images showing Lovejoy rising tail first in the sky this morning.

Australia’s IceinSpace amateur astronomy site has a forum on which members are posting their Comet Lovejoy images here.

Of course for the superstitious, Comet Lovejoy enhances the legendary association of bright comets with the death of tyrants and kings, given the departure of Kim Jong-il.

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