Subscribe

Brighter Comet Yet to Come in ‘Year of the comet’

Earth in a ‘cosmic shooting gallery,’ says scientist

By Justina Reichel
Epoch Times Staff
Created: March 11, 2013 Last Updated: March 14, 2013
Related articles: Canada » National
Print E-mail to a friend Give feedback

Comet Pan-STARRS (L) is seen with a one-day-old crescent moon as both set over the Very Large Array radio telescope antenna dishes March 12, 2013, near Magdalena, New Mexico. The comet, now just faintly visible in the Northern Hemisphere, was discovered in June 2011 by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii. (Stan Honda/AFP/Getty Images)

Comet Pan-STARRS (L) is seen with a one-day-old crescent moon as both set over the Very Large Array radio telescope antenna dishes March 12, 2013, near Magdalena, New Mexico. The comet, now just faintly visible in the Northern Hemisphere, was discovered in June 2011 by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) in Hawaii. (Stan Honda/AFP/Getty Images)

While stargazers are getting a treat this week with a sighting of the Pan-STARRS comet, astronomers say another comet expected to streak past Earth in November will be a once-in-a-century experience—the highlight of what’s being dubbed “the year of the comet.”

Comet Pan-STARRS, named after the Hawaiian telescope that discovered it two years ago, made its way into the Northern Hemisphere last week, and will be most visible to the naked eye over Canadian skies this Tuesday and Wednesday.

Comets that are visible from Earth happen about every five to ten years, but the upcoming comet ISON will be much closer and brighter—the kind of comet that appears only once a century, says Roy Gal, assistant astronomer and outreach coordinator at the Institute for Astronomy at University of Hawaii.

“ISON is going to go extremely close to the sun, much closer than Comet Pan-STARRS,” Gal said in an interview.

“So it’ll get activated a lot more by the sun’s heat, which means that it will throw off more gases, which is what reflects the sunlight that we see as the tail and the head of the comet.”

Having one naked-eye comet is already a rare thing, but having two in one year is extremely rare.

— Roy Gal, Institute for Astronomy, University of Hawaii

Comets are made up of ice and dirt in a kind of “dirty snowball,” Gal explains, so when they get close to the sun the ice turns into a gas. The more gas the comet emits, the more sunlight gets reflected and the brighter it looks.

“Having one naked-eye comet is already a rare thing, but having two in one year is extremely rare, and especially to have one that’s going to be as bright as ISON is predicted to be,” says Gal.

“To have two comets that we can see with our eye in a year happens probably once every couple of hundred years.”

Comet ISON is expected to appear in late November. If it gets too close to the sun, however, it could break apart before it becomes visible.

Rash of Asteroids

Meanwhile, scientists reported this week that four asteroids, one as large as a city block, passed relatively close to Earth—all within a seven-day period from March 4 to 10.

The largest, Asteroid 2013 ET, passed about 950,000 km from Earth—a distance approxmately 2.5 times as far away as the moon.

“The scary part about this one, of course, is that it’s something we didn’t even know about,” said Patrick Paolucci, president of the online Slooh Space Camera, during a live webcast of the asteroid’s flyby.

At 140 metres, Asteroid 2013 ET measured nearly eight times larger than the meteorite that exploded over Chelyabinsk, Russia, on Feb. 15. The force of its impact created a shock wave that shattered windows and damaged buildings, injuring more than 1,200 people.

Later on Feb. 15, another asteroid, 2012 DA14, passed within 27,700 km of Earth—closer than many communications satellites. After the flyby, which was closely tracked by astronomers, Planetary Society scientist Bruce Betts said Earth is essentially in a “cosmic shooting gallery” in terms of asteroids.

It’s only in the last decade or so that we’ve had systems that can find [comets] and give us plenty of early warning.

— Roy Gal, Institute for Astronomy, University of Hawaii

Asteroids such as the one that hit Russia impact Earth about every 50 years but can be difficult to predict because they tend to be much smaller than comets and are made of solid rock, which does not reflect sunlight well, making them more difficult to see coming.

“The asteroid that hit Russia was, one day before it got to us, so faint that none of our telescopes could have detected it, whereas the comet is much bigger and brighter, even when it’s far out in the solar system,” Gal says.

It’s not that there are more comets and asteroids passing by earth, he notes, but that scientists are developing better systems to detect them.

“It’s only in the last decade or so that we’ve had systems that can find [comets] and give us plenty of early warning,” he says.

“In the past we probably would have only a week or a month’s worth of notice that each comet was coming, and then it would have been more of a surprise. Now we know that both are coming in a year, and so we’re kind of geared up for it.”

Dangerous Fireball

The last comet thought to impact Earth occurred over 100 years ago and was dubbed the “Tunguska event.”

In a remote part of Russia on June 30, 1908, a fireball was observed streaking across the sky before a large explosion in the atmosphere above Siberia’s Podkamennaya Tunguska River, what is now Krasnoyarsk Krai.

The event—the largest-ever recorded explosion of a space object plunging to Earth—is believed to have been caused by an incoming meteor or comet. The object never actually struck Earth but instead exploded in the atmosphere, causing an air burst 5–10 kilometres above Earth’s surface.

The blast’s impact felled an estimated 80 million trees across 500,000 acres of Siberian forest and is thought to be 1,000 times more powerful than the impact of the atomic bomb dropped on Hiroshima, Japan.

The Epoch Times publishes in 35 countries and in 21 languages. Subscribe to our e-newsletter.




GET THE FREE DAILY E-NEWSLETTER


Selected Topics from The Epoch Times

Asia Week NY Spring 2013