By Professor Todd Brown / Contributor

This time of the year is gloomy for me. There’s at least one more month of cold weather. So, as I sat typing this week’s column about the Orion Nebula, I barely batted an eye when my wife looked up from her Internet connection and said “Did you hear about the world almost coming to an end on Wednesday? ” Hmm, actually, I had.

That cold breeze you felt on the 30th could have been a lot worse if 2007 TU24 had deviated a little. Those numbers aren’t a meteorological postal address showing the origin of artic blasts, instead it was a 400 foot asteroid that drifted to within 330,000 miles of the earth. Even though the moon’s orbit is a little closer, it was a little too close for astronomers used to dealing with the vastness of the solar system. It did “hit” my column, as I decided to table the one I was writing and re-start, figuring that I should write about what has broken into the main press.

If that oblong piece of rock had hit us, the world wouldn’t have ended but someone would have gotten the big hurt put on them. If downtown Pittsburgh had been 2007 TU24’s final resting place, then the city would have been replaced with a crater about a mile wide and the shock wave would have assured us that classes at Pitt-Greensburg, as well as most of us that study and work here, would have been permanently cancelled. Such are the simple rules to the pinball game that deals with Near Earth Objects, NEO for a cool short name, and eventually our number will be up.

Before you panic and decide against studying for your midterms, keep in mind that no person has been known to have met an early demise by a falling piece of space rock. There have been documented accounts of a woman being bruised by one, a few homes have had to be re-roofed because of others and there was the Canadian golfer a few years ago that almost got more than he bargained for on the Back 9, but no fatalities. These former instances have all been basketball-sized or smaller rocks that crash into the atmosphere and are slowed by friction to a leisurely pace of a few hundred miles per hour before impact. Deadly to individuals if hit directly, they are small and we provide an even smaller target. The real worry comes from the 2600 plus stadium-sized or larger asteroids that cross the earth’s orbit. From that group of 2600, six hundred are bunched by astronomers into the category referred to as “potentially dangerous.” It doesn’t take much thinking to realize why they are named this.

NASA and astronomers throughout the world carefully watch these 600. Their orbits are tracked and projected as far into the future as possible to see if we might be heading for a very close encounter. Unlike baseball batters, these rocks have as many misses as eternity permits. Eventually they will hit something. The bad news is that to pinpoint exactly where these rocks will go means we have to know as much as possible about them. Case in point, 2007 TU24 was photographed by astronomers and was seen to be a blurry, dark object. We don’t know its exact shape and we don’t know its mass exactly. This is vital because every swing by earth or other large object, say the moon, will result in a changing of the asteroid’s orbit due to gravitational interaction. The less reliable we know its mass, the less reliable we can predict where it will go.

On Christmas Eve in 2003, we were paid a visit by St. Nick and 2004 MN4. It didn’t get closer than 9 million miles. That was no threat … for 2003’s encounter. Astronomers quickly computed its orbit into the future and initial calculations showed that on April 13, 2029, this 1000-foot-rock had a 1-in-40 chance to slam into the Pacific Ocean (Surf’s up, way up, Hawaii). People play the Lottery and the odds aren’t anywhere close to that good so other groups quickly got involved into looking at 2004 MN4. When the new numbers were crunched it turned out that the rock would miss earth by a razor thin 20,000 miles. But, depending on its exact mass and orbit, during the 2029 pass it could enter an area in space euphorically termed “the keyhole”.

The odds of 2004 MN4 going into the keyhole are small, 1-in-45,000. But, if it does, then the earth is back in its crosshairs in 2036. Actually, the astronomy community worries not that much about the 600 “potentially hazardous” asteroids. It is the 601st one, the one that we don’t know about, that keeps us, literally, up at night. Unfortunately, most of these asteroids are found in photographs accidentally after a close approach to earth. Imagine waking up every so many mornings and seeing a new bullet hole in your bedroom window. Saying, “Whew, that was close” would be an understatement. A few times a year, astronomers wake up to just such a morning.

What is needed is better surveillance with dedicated systems. NASA proposed this recently. If we had years to plan prior to the impact, maybe we could do something to divert the asteroid. Nothing would motivate the world to work together as to avoid a date on the calendar having the words “World Ending Armageddon Day.” NASA projected they could locate over 90 percent of the estimated 20,000 hazards by 2020. These objects range in size such that they could do anything from destroy a city to bring about the end of civilization.

When NASA’s Planetary Defense Conference (gotta love the name) was held in 2007, their target goal was applauded but the smiles disappeared when the price tag was given: $1 billion. Since one could buy several of those Alaskan “bridges to nowhere” for the same price, the project was sacked by Congress. You have to sympathize with Capitol Hill. What looks better on a postcard: a fancy new bridge with the catchphrase “Wish you were here!” or a group of scientists in lab coats squinting through a telescope with the phrase “Oh, please don’t be coming!” NASA does have money to search for the really big, Dinosaur-Demise type asteroids, but the US has the only government agency with an asteroid tracking program. To make up for the other stuff that would only wipe out a small state or country, there is a lone Italian observatory that is trying to do the job. So don’t worry, you can still plan a lengthy trip for Spring Break as the world shouldn’t end before March. If money is available, I would head to Italy as those dozen scientists on their mountaintop observatory could probably use a little help.

What else is out there this week: