Rare 4000-year comets could affect Earth, resulting in a displays of shooting stars — and a chance of catastrophe.
As Earth orbits the Sun, our planet regularly passes into the path of (largely) rocky debris left behind by comets which pass close to the orbit of our home world.
Some comets travel close to the Sun, orbiting quickly (constantly refreshing the supply of debris along their path). Others take hundreds or thousands of years to complete a single orbit. Debris from these long-period comets, some of which can take 4000 years to make a single circle of the Sun, is usually too thin to measure, or escapes to interstellar space.
As new cameras begin to view the night sky (particularly in Australia, Chile and Namibia), researchers are able to determine the origin of a growing number of meteors seen streaking across the sky.
“In recent years, the CAMS (Cameras for Allsky Meteor Surveillance) low-light video camera network was greatly expanded and, together with other video networks, now has increased the total video meteoroid orbit database to over 2.2 million orbits,” researchers report in the journal Icarus.
Now, a new study from the SETI Institute reports material from long-period comets can create shooting stars, and even fall to Earth as meteors. Orbits of comets examined in this study ran from bodies with 250-year orbits to 4000-year-comets.
“Until recently, we only knew five long-period comets to be parent bodies to one of our meteor showers, but now we identified nine more, and perhaps as many as 15,” explains Peter Jenniskens, meteor astronomer at the SETI Institute.
You Think You’re Tough? Comet Me!
“Comets are like cats: they have tails, and they do precisely what they want.” ― Astronomer David Levy
Earth is continually impacted by objects from space. Smaller fragments of rock, metal, or ice are incinerated as they race through our upper atmosphere. A small percentage, however, fall to Earth as meteorites. Occasionally, collisions with the largest bodies result in massive explosions, like the wayward asteroid that ended the age of dinosaurs.
Although comets make up just a small fraction of impactors to strike Earth, their long periods and high velocities make comets potentially hazardous. Comets are responsible for some of the most powerful impacts in the history of our planet.
“This creates a situational awareness for potentially hazardous comets that were last near-Earth orbit as far back as 2,000 BC,” Jenniskens explains.
These bodies — up to and including 4000-year comets — can result in meteor showers that last several days, researchers concluded.
Comets that last visited Earth forty centuries ago, as the Sumerian culture faded, copper tools became common, and silver was first used as money, may still produce a few of the shooting stars we still see today when we look up to the night sky.
James Maynard is the founder and publisher of The Cosmic Companion. He is a New England native turned desert rat in Tucson, where he lives with his lovely wife, Nicole, and Max the Cat.
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