Factual Friday

It is possible that on this day in 1178 five monks in Canterbury witnessed the formation of the Giordano Bruno lunar crater. They reported to their chronicler, Gervase, that they saw two horns of light coming from the shaded part of the moon. Theories suggest that when a meteorite hits the moon there would be plumes of molten rock, which may have been what the monks were describing. Also, the ray system (the bits blasted from the impact) is unfaded and the rim is still visible, suggesting it is quite recent. Well, less than 350 million years young. However, an impact of this size on the moon would have affects on Earth, but nothing of the sort was recorded in any civilisation at the time.

Earth has its own mysterious impact sites. One of these is found in Russia, and is known as the Tunguska event. It happened on 30th June, 1908 at thirteen minutes and thirty five seconds past midnight, Greenwich Mean Time. What is thought to have happened is that a meteorite or comet fragment exploded between 5-10km above the Earth's surface. The explosion felled about 80 million trees, over an area of 2150km². Although there is no crater, a lake may have been formed by a fragment of it.

These two events, although 730 years apart, may be linked. They both could have been caused by the Beta Taurid meteor shower that occurs during June and July each year. However, there's no point in trying to go out at night and observe them, because the meteors approach from the day time side so the sunlight renders them invisible.

However, if you want to see an astrological event the Comet McNaught is visible in the UK's sky at the moment. It will be at its brightest on June 22nd. Comet McNaught, or C/2009 R1 as about fifty comets are called 'Comet McNaught' (Mr McNaught keeps on finding the things), is not one that will be coming back, like Hale's Comet, so this is the only opportunity ever to see it. It's most likely to be spotted at dawn or dusk.

That is the end of another Factual Friday.