Target Earth: A Galaxy of New Films Fret That the Sky Is Falling
Nearly 65 million years ago, a large comet or asteroid slammed into the Yucatan Peninsula from the southeast at a 20-30 degree angle. The resulting blast wave sent most of North America up in flames within a matter of minutes.Roast dinosaur, anyone?The rock that fell from the sky was 6 to 12 miles across and hit with the impact of 120 trillion tons of TNT, according to Virgil Sharpton, an astronomer with the Lunar and Planetary Institute, which published its report in "Sky and Telescope." The object gauged out the basin we know today as the Gulf of Mexico. At least one astronomer believes that the inertia from the strike "possibly caused the formation of Mount Everest and the Himalayas on the opposite side of the globe in the northern hemisphere."More importantly, the skybomb obliterated countless species on Earth."The asteroid hit a geologically unique, sulfur-rich region of the Yucatan Peninsula and kicked up billions of tons of sulfur and other materials into the atmosphere," says V.L. Sharpton, LPI, writing in "Sky and Telescope." "Darkness prevailed for about half a year after the collision. This caused global temperatures to plunge near freezing. Half of the species on Earth became extinct including the dinosaurs."Stars of the Silver ScreenThis summer, residents of Planet Earth will learn far more about asteroids, comets and meteoroids than they may wish to know, with the arrival of "Deep Impact," a film that's likely to generate a cloud of media debris as vast as a planetary collision."Deep Impact" comes on the heels of the "Asteroid" television miniseries, and just ahead of "Armageddon," a Disney asteroid flick due out July 1. Then too, recent sci-fi films such as "Starship Troopers and The Fifth Element" offered their take on doom from the sky. Asteroids, it seems, are much in the public imagination these days."Deep Impact" is about a comet on a collision course with Earth, which neither the President (Morgan Freeman) or an aging astronaut (Robert Duvall) can stop. Trailers from the film show the sort of earthshattering damage one can expect of such a collision, including the engulfment of coastal cities by tidal waves.It's not a pretty scenario, and the best that Earth's defenders can come up with in the film is an attempt to deflect the comet so that we don't all end up resembling road kill on the cosmic highway.The Fire Next TimeAsteroids are believed to be debris left over from the creation of the solar system, although one theory holds that they were created by the collision of a small planet.Thousands of asteroids orbit in a belt between Mars and Jupiter, ranging from the size of pebbles to that of Ceres, a mini-planet 600 miles in diameter. According to NASA, 16 asteroids have a diameter of 160 miles or greater.Here's the catch: although the asteroid belt is tens of millions of miles away, it's also true that asteroids have been found ranging from inside the Earth's orbit all the way out to Saturn.That means that periodically, Earth has an unwelcome visitor. The Barringer Meteor Crater near Winslow, Arizona, is one example of what happens when worlds collide, as is the case of a meteor which fell on Siberia in 1910, destroying forests as well as animal and human populations for hundreds of miles from the impact site.Mass ExtinctionExtinction is a part of nature and evolution -- biologists claim that more than 90 percent of all species which ever existed become extinct over time. Things like segmented worms, stegosaurs, trilobytes, mastodons, neanderthals, and five-eyed creatures scuttling on the Devonian Age ocean floor.Then there's mass extinction -- the sudden die-off of nearly all life on Earth due to a catacylsmic event.In his book, "Extinction," paleontologist Steven M. Stanley notes that there have been at least eight mass extinctions throughout Earth's 4 billion year history, each of which brought the following ages to a close: Precambrian, Vendian, Cambrian, Ordovician, Devonian, Permian, End-Cretaceous, and the Holocene Age."Extinction strikes in both the land and the sea," Stanley writes. "On the land, while animals suffer repeatedly, plants tend to be highly resistant to mass extinctions."Mass extinctions arise from both the sky and the earth in the following forms:1.Catastrophic Agents- such as meteorite impacts and comet showers,2. Earth Agents- such as volcanism, glaciation, variations in sea level, global climatic changes, and changes in ocean levels of oxygen or salinity.Who You Gonna Call?So what can you do to about the threat of asteroids striking the Earth?Nothing, so relax and enjoy the films.And be secure in the knowledge that NASA at least is looking into the matter. In June, 1997, the spacecraft NEAR made a high-speed close encounter with asteroid 253 Mathilde. The NEAR orbiter is scheduled to visit asteroid Eros in January, 1999.Hopefully, NASA will keep us posted.Robert Downes is editor of Northern Express Weekly in Traverse City, Michigan. A Cosmic Glossary:Asteroids -- rocky and metallic objects that orbit the Sun but are too small to be considered planetsComets -- A large, cloudlike ball of dirt, ice and frozen gases which travel in elliptical orbits around the Sun and back into deep spaceMeteoroids -- basically an asteroid that's on a collision course with Earth. A meteor is the streak of light seen shooting through the atmosphere, while a meteorite is what's left when the object hits the Earth.E.L.E. -- an "Extinction Level Event"N.E.O. -- a "Near Earth Object"Mass Extinction -- there have been at least 8 mass extinctions of life in Earth's natural history, and possibly as many as 12, due to asteroid strikes, volcanism, glaciation, and changes in oceanic salinity.