Planets climb out of sun's glare

The month of April holds the great awaited day, no not tax day, astronomy day. April 20 is designated National Astronomy Day. While no special events are planned locally, as far as I know, celebrate the night by taking a look outside on that evening.

The great planet alignment of 2002 will be one the best in the past 20 years and it starts toward the end of this month and continues through May. Mercury, Venus, Mars, Jupiter and Saturn undergo a complicated dance after sunset in the west. Noticeable close conjunctions will start on May 3 with Mars and Saturn. Venus continues to make itself noticeable as it climbs higher each night trying to escape the glare of the sun. Towards the end of the month even Mercury will be seen climbing out of the glare.

We begin our transition into summer as Orion sinks into the horizon leaving the evening sky till next winter. With the loss of Orion the summer constellations rise in the east to take his place. By midnight the Milky Way can be clearly seen. Leo the lion is high in the south looking down on his territory. In the north the Big Dipper rides high and upside down.

An added treat is a bright comet low in the northwest. Although bright by comet standards, binoculars are definitely needed. Unlike the last bright comet, which had a wide fan shaped tail, this comet has a long pencil shaped tail with a bright starlike nucleus. It will take dark, clear skies to see it well.

We had a near miss collision with an Earth-crossing asteroid last month, which was estimated to have come about as close to the Earth as the Moon. Even though astronomers have been looking for these kinds of killers, this one came in from the direction of the sun so we could not see it until it passed us by. There are estimated to be about 1,000 asteroids half a mile wide in size, which cross Earth's orbit and thus have the possibility of colliding with us.

Even though 1,000 seems like a lot, from a statistical point of view we only expect to be hit by one every few 10,000 years or so. An impact by a half-mile wide asteroid would unleash more energy than all the nuclear weapons mankind has ever produced. It would totally vaporize most larger cities and wreak havoc hundreds of miles away and send debris high into the atmosphere which would stay up there for several years.

Some people would just as soon not know the end is coming. After all, there is little we could do about it. NASA currently spends about two years preparing for missions. The idea that NASA would put a team of old retired guys together and launch the shuttle in a week's time must have many space officiators grimacing on the side.

I remember seeing on the TV news last year that a young boy heard something hit the ground in front of him while walking home from school one day. When he looked down he saw a charred rock about the size of his fist sitting in a small impact crater. I would definitely make a paper weight out of that one.

Dr. Mike Cobb is a professor in the physics department at Southeast Missouri State University.