Jun 01

June 2008

What’s Up in the Sky June, 2008
By Peter Burkey

We live in a more or less placid, stable world. Changes occur, but slowly. Although recent events may indicate otherwise, most of us live full lives never encountering a natural disaster more violent than a storm and so we are fairly complacent. The geological record, however, is clear – widespread devastation and major catastrophes are common occurrences albeit on a very long time scale. But in just the last century, there have been bizarre natural events. One such event happened 100 years ago next month.

Early in the morning of June 30, 1908, the Tungus people of central Siberia were violently awakened by a giant fireball racing across the sky. Soon thereafter an enormous explosion shook the ground, followed by searing winds and a huge forest fire. Some folks were thrown into the air, even knocked unconscious. Horses bolted, windows shattered, and thousands of trees were leveled. The explosion produced an atmospheric shock wave that circled the Earth twice. So much dust was kicked up into the atmosphere that for two days Londoners could read a newspaper at night illuminated by the scattered light.

Little was known about the Tunguska Event, as it came to be called, since the Czarist government in Russia considered it to be of little importance, having occurred in such a remote area among backward inhabitants. In fact, it wasn’t until 1930 that an expedition of scientists journeyed to the area to gather evidence and hear eyewitness accounts. Slogging through endless swamps and plagued by voracious mosquitoes, they found complete devastation with trees burned or stripped bare lying on the ground, all pointing away from the point of impact. What they did not find, however, was an impact crater or any evidence of pieces of the original object.

Many hypotheses were proposed to explain the event. Among the more interesting were a piece of antimatter completely annihilated when striking the normal matter of Earth, or a mini black hole that passed through the Earth in Siberia and out the other side. Some even postulated than an alien spacecraft from an advanced civilization experiencing engine trouble crashed. More plausibly it was thought to be a comet fragment that exploded high above the ground, hence no crater.

The most recent theory, based on our better understanding of atmospheric meteorite explosions and supported by new evidence, suggests that it was an exploding stoney meteorite. No matter what its cause, we should be glad it happened in a distant remote area or it packed the wallop of a large H-bomb. Perhaps the next time we will have advanced warning and be able to avoid the devastation caused by uninvited visitors from up in the sky.

Here are this month’s viewing highlights:
Planets this month: Mars closes in on Regulus and Saturn low in SW in the early evening. Jupiter continues to dominate the southern predawn sky.

June 3: New Moon – closest of the year.
June 7-9: Watch Moon pass line of objects Mars, Regulus, Saturn.
June 10: First quarter Moon.
June 18: Full Moon.
June 26: Last quarter Moon.
June 30: Mars and Regulus form close pair.