Published: November 28, 2008 07:47 pm      

Don’t worry; it’s not likely to happen soon

Threats to our existence with humor

Not a day goes by without some article or media presentation on the latest danger to humans.

With widespread layoffs, overseas wars, crime in our cities and diseases out of control, there’s not much to be cheerful about. This is why the new book “Death from the Skies” can give us a sense of perspective. This popular science book is the equivalent to the scary horror movies that used to keep people awake at night.

The author, Dr. Philip Plait also wrote “Bad Astronomy,” treating the numerous wrong ideas that people have about the heavens. Now Plait treats all manner of threats from space that might wipe out the human race. Thankfully, the odds that any of these will happen in our lifetimes is close to zero. But these possibilities make any of our misdoings seem rather tame.

Did you know that every day, 20 to 40 tons of meteors strike the Earth, each meteor hitting the upper atmosphere at up to 100,000 miles per hour? But once a month, a rock from space about a meter across comes down, exploding with the energy of hundreds of tons of TNT.

If we wait long enough, a space rock miles across will hit, such as the 6-mile wide asteroid that hit Mexico 65 million years ago, wiping out all large animals (including the dinosaurs). The crater formed was 200 miles across and 20 miles deep. This impact killed 75 percent of all life on Earth. Fewer than two dozen astronomers work on detecting Near Earth Asteroids (NEA), whose orbits can be predicted years ahead. We don’t have as much advance warnings about comets, which can come from all directions.

Luckily, the comets are more likely to break up in the atmosphere and cause throw less material into the air. But a big comet striking any of the oceans would create huge tsunami waves that would wash over coastal cities such as New York, Los Angeles, London, Tokyo, etc. Dr. Plait details strategies that with long enough lead time could deflect these objects (so they would not hit the Earth).

Another threat to the Earth on a much longer time scale is our evolving sun. Our sun’s power is from nuclear fusion, the conversion of hydrogen to helium with less than 1 percent of this matter being turned into radiant energy. But our sun’s hydrogen will eventually dwindle. As our sun develops a helium core, it will swell into a giant star, greatly increasing the energy it throws into space.

The Earth and other inner planets will be scorched. This cruel roasting of the inner planets will not take place for several billion years. Plait outlines a plan to use an asteroid to propel the Earth into a larger orbit so we will avoid getting barbequed.

The rarer threats Plait mentions include a Gamma Ray Burster, a direct beam of gamma rays that would attack all life forms and our atmosphere. It’s more likely that our sun and planet were to pass by aged star that explodes (supernova). If this supernova is within a few dozen light years of Earth, the radiation from the exploding star would destroy our ozone layer; then our own sun’s radiation would do us in. The widely acclaimed black holes have a sinister allure of their own.

A black hole coming into our solar system would start pulling the planets out of their orbits. If a stellar black hole came near the Earth, the Earth would be stretched, greatly heated and then completely devoured by the black hole. The nearest known black hole is Cygnus X-1, about 1,500 light years away. The far future is bleak. Eventually all the stars will burn out, then there will be an era of black holes where the stars and planets will be consumed.

Eventually in very distant future, even the black holes will evaporate, disappearing with a bang. Many hundreds of trillions of years from now, the universe will be very cold, very close to empty and completely dark.

Moon-Venus-Jupiter tomorrow

Tonight if your western horizon is flat, look about 5:30 p.m. for a very slender moon, the brilliant planet Venus and the bright planet Jupiter. Tomorrow night at the same time, the crescent moon will be just to the left of the Venus-Jupiter pair.

Then the moon, Venus and Jupiter should fit into the field of view of a low power binoculars. Through binoculars, you will be able to see the moon’s gray plains and tiny points near Jupiter (its larger moons). By Friday, the evening moon will appear half full, offering the best views of its craters and mountain ranges through binoculars (held steadily) or a telescope.

The Frostburg State University Planetarium will be closed today and will reopen next Sunday with “Skies of the Holy Lands,” featuring the skies as seen by Abraham, Moses, at Jesus’ birth and by Mohammad. To get a free planetarium calendar, call (301) 687-7799 and leave your name and mailing address.

Readers are invited to email Bob Doyle with any comments or questions. Contact Bob Doyle at rdoyle@frostburg.edu.