May 01

May 2008

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

It was Saturday, September 15, 2007, at 11:45 a.m., when 74-year-old Justina Limache, a farmer in Carancas, Peru, not far from Lake Titicaca, heard a “thunderous roar from the sky.” Scared, she ran into her house clutching her 8-year-old granddaughter. For the next few minutes, she feared her house would be destroyed by rocks raining down on the roof. What Justina Limache did not know was that a meteorite had fallen near her home in the little farm community of about 2,000 people near the Bolivian border. The impact left a crater some 45 feet across and spewed debris as far as 500 feet! Luckily, no one was injured.

Was this a rare, isolated event or a reminder of the potential danger we face living on planet Earth? Yes. Meteorite impacts are relatively rare but every now and then one poses a real threat.

Clearly, impact events are common in the solar system. One look at our Moon reveals a surface pockmarked with craters and just about every other planetary satellite we have imaged shows the same characteristic features. Here on Earth, most meteorite craters have been wiped out by wind, water, or geologic activity with some notable exceptions such as the Barringer Meteor Crater in Arizona. However, astronomers believe that Earth must have been impacted numerous times throughout history, with most being of the small, localized nature, but a few causing global devastation.

Could it happen again? Probably. But the fact that most of the debris left over from the solar system’s formation has already been swept up makes the probability of such an event extremely small – but not zero. For this reason, a small number of scientists are constantly monitoring the skies for “NEOs” – near Earth objects, mostly asteroids whose orbits intersect (or come close to) that of Earth. Several such objects have been discovered in recent years and some have passed as close as the Moon. There have even been discussions regarding ways to deflect or destroy such harbingers of disaster (remember the movie “Armageddon”?).

Given the remote possibility of such an event, we probably have ample time to come up with a plan to protect us from uninvited visitors from up in the sky.

This month in history:
May 1: One of Neptune’s moons, Nereid, discovered by Gerard Kuiper – 1949
May 6: Neil Armstrong ejects safely before Lunar Landing Research Vehicle crashes – 1968
May 24: Mercury astronaut Scott Carpenter becomes first American to eat food in space – 1962
May 28: Rhesus monkeys Able and Baker are first primates in space – 1959
May 31: European Space Agency formed – 1975

Here are this month’s viewing highlights:
Planets this month: Saturn and Regulus in Leo form a striking close pair all month. Mars fading in west at dusk. Mercury visible low in WNW at dusk first half of month. Jupiter continues to dominate southern predawn sky.

May 5: New Moon.
May 6: Mercury between thin crescent Moon and Pleiades – one hour after sunset.
May 11: First quarter Moon
May 19: Full “Blue” Moon – third Full Moon of the season.
May 21-24: Use binoculars to see Mars pass through Beehive cluster.
May 27: Last quarter Moon.