Starwatch: Mercury in view

It is not our moon, but recently published a mosaic of the planet Mercury as seen in images from NASA's MESSENGER probe. Despite representing an entire hemisphere of the smallest planet, shadows delineate several characteristics and, of course, be visible if it were a real "Mercury full" view from the direction of the sun.

The most important characteristics are the impact basin Tolstoy dark bordered, about 350 km in diameter and just under the right of center, and the enormous Caloris Basin, located in quadrant the top left. It, 1550 miles across and one of the largest structures of its kind in our solar system, is just north of the Mozart 225 km from the crater.

Although there is little interest in the effort to detect these features on the Earth, Mercury is the start of a race in favor of the poor visibility within the department Economy in our morning twilight. A view of Britain from 13 to 29, amounts to more than 100 minutes before sunrise and walk between 8 ° and 10 ° height thirty minutes before sunrise. Brightness of magnitude 0.5 to -0.4, must become an object visible to the naked eye and binocular easy if our horizon is clear. Through a telescope, its phase varies between 28% and 76% sun that its diameter is reduced from 8.5 to 5.9 seconds of arc.

not forget the imminent peak of 14 on Wednesday, the Geminids meteor shower of the year. Its bright meteors are relatively slow and occur in all regions of the sky, although their paths separated from the radiant point near Castor in Gemini, N and E (left) of Orion. Low in the northeast at dusk, this radiation is from about 70 ° S at the top at 02:00. The problem this year is that the moon is bright behind only an hour late to the harsh light of bright meteors and smaller. Ideal moonless sky could have given the number of meteors above 100 per hour.

Finally, astronomers see a comet to the limit Sun discovered by Australian amateur astronomer Terry Lovejoy, Nov. 27. With an orbit that takes about 150,000 km from the Sun at midnight GMT on December 15-16, Comet Lovejoy belongs to the Kreutz family of comets sungrazer have produced some of the greatest comets of all time.

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hundreds of comets of this type were seen in images from around the Sun taken by the SOHO spacecraft, but it seems that all this was of small icy bodies, any more than a few meters wide, and none survived a meeting of fire to emerge and fly away in their sockets. The same fate may await the new comet, but since this is the first sungrazer Kreutz be known around the world since 1970 may be bigger and stronger.

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