Meteor shower could reveal primordial elements

This Labor Day weekend might feature the most spectacular night show ever – or it might not. Earth will pass through a trail of particles left behind by the Comet Kiess on Sept. 1, a potential follow-up to the total lunar eclipse that occurred on Tuesday morning.

The last time it came near Earth was in 1911, creating a meteor shower known as the Aurigids (Aw-rye-gids). There’s a continuous stream of those particles passing by Earth, but only when the gravitational pull of the planets alters the stream into the planet’s path do we actually see a shower. The Aurigids are named from the nearby constellation Auriga, also known as the Charioteer.

Prior to 1911, the last time Comet Kiess was anywhere near the inner solar system was approximately 83 B.C., when Julius Caesar was still alive. Earth has passed through the particle field three times before, but the events were largely unexpected and mostly unobserved.

Because Comet Kiess is what’s called a “long-period comet” and Earth’s astronomers have so little experience with the debris left behind from such comets, many aren’t sure as to what will happen: a large meteor shower with over 1000 meteors in an hour or a smaller show with up to 100 meteors an hour.

A “long-period comet” has a large, elliptical orbit, and for much of its life it lingers in the dark part of the solar system near the Oort Cloud where comets usually form. While in the outer solar system, they lack the characteristic tails, as those are only seen when the comets’ gas is superheated due to proximity to the sun. Not having those tails means long-period comets are much more difficult to detect and their orbit is difficult to pin down. Comet age is also partially based on the orbit, so astronomers aren’t sure just how old Kiess is or what its leftover particles are, only that it’s at least 2,000 years old.

Long-period comets like Kiess can also pose an impact threat, but Debi Prasad Choudhary, a physics and astronomy professor at CSUN, doesn’t think the Aurigids will be a danger to anyone.

“Not this one. It’s small,” he said. “Other meteors from asteroids and so on are (more) dangerous.”

Though it’s not Kiess that’s coming, the meteor shower can help figure out just where Kiess is lingering based on the orbit of the meteoroids.

Unlike short-period comets and their subsequent meteor showers, such as the Leonids and the Perseids, which pass through the solar system every few centuries, long-period comets like Kiess are rarely in the sun’s light, meaning both the comet and its particles are quite primitive, the Ames Research Center, hosted by the SETI (Search for Extra-Terrestrial Intelligence) Institute, reports.

“If you can know what elements (are) in this comet, you can form a better solar system model,” Choudhary said. Because the comet and the particles leftover from its last pass-through of our solar system might be primitive, dating back thousands or even millions of years, its icy surface has preserved the original metals inside, leaving them in their pristine state, as they were when the comet was first created. This means that when the Aurigid meteors actually fall, that “pristine crust” might produce some rather interesting colors in the nighttime sky.

NASA has found that a lot can be discovered about a comet or a meteor just by looking at its tail. Various elements will burn different colors Because Comet Kiess is a long-period comet and its meteors are likely to have that “pristine crust,” knowing what elements they contain can help astronomers construct a more accurate model of the forming of the solar system. Current models have the Big Bang taking place 4.5 billion years ago. And while Kiess isn’t that old by any stretch of the imagination, the fact that it’s still a long-period comet, while the more frequently-sighted Leonids and Perseids are short-period comet meteors, does indicate that it’s quite old.

Though there’s no way to definitively predict if the Aurigids will produce 100 meteors in an hour or 1,000, “it’s very worth it to see the meteor shower,” Choudhary said. He recommends going to a dark place without any obscuring buildings or light sources.

“If you (choose to) sleep on the ground, you should be able to see the horizons on either side of you,” Choudhary said. Places such as large parks, Big Bear Lake, or mountaintops are ideal for meteor shower spotting, and many campgrounds will also serve that purpose.

Residents of Southern California are particularly in luck, as the meteor shower has its highest visibility in states west of the Rocky Mountains. The shower is expected to peak at about 4:36 a.m. PDT, plus or minus 20 minutes.

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