Host: Fraser Cain
Astrojournalist: Morgan Rehnberg(cosmicchatter.org / @cosmic_chatter)
Continue reading “Weekly Space Hangout – April 11, 2014: Exomoons, Eclipses & Launches”
Around this time last year a space rock crashed into the Earth above Chelyabinsk, Russia. It brightened the skies for hundreds of kilometers, broke windows and injured many people. Let’s look back at the event. What happened, and what did we learn?
Continue reading “Astronomy Cast Ep. 334: Chelyabinsk”
A half-ton meteorite — presumably from the Russian fireball that broke up over Chelyabinsk in February — was dragged up from Lake Chebarkul in the Urals, Russian media reports said. Scientists estimate the chunk is about 1,260 pounds (570 kilograms), but couldn’t get a precise measurement in the field because the bulky bolide broke the scale, according to media reports.
“The preliminary examination… shows that this is really a fraction of the Chelyabinsk meteorite,” said Sergey Zamozdra, associate professor of Chelyabinsk State University, in reports from Interfax and RT.
“It’s got thick burn-off, the rust is clearly seen and it’s got a big number of indents. This chunk is most probably one of the top ten biggest meteorite fragments ever found.”
The big rock was first spotted in September, but it’s taken several attempts to bring it to the surface. If scientists can confirm this came from the fireball, this would be the biggest piece recovered yet. The chunk is reportedly in a natural history museum, where a portion will be X-rayed to determine its origins.
More than 1,000 people were injured and millions of dollars in damage occurred when the meteor broke up in the atmosphere Feb. 15, shattering glass and causing booms.
Since then, there have been numerous papers concerning the meteor’s origins (from the Apollo class of asteroids — you can read this article if you’re unclear on the difference between an asteroid and a meteorite) and tracking the spread of dust through the atmosphere, among other items.
Last week, Russian researcher Andrei Zlobin announced that stony fragments collected from a riverbed in 1988 are “probably Tunguska meteorites,” and are likely the remains of whatever cosmic object — thought to be either a comet or an asteroid — entered Earth’s atmosphere over the boggy region of Siberia on June 30, 1908, detonating with an estimated force of 5 megatons and leveling over 800 square miles of forest.
So far, definitive pieces of the original object have yet to be found despite numerous expeditions to the remote impact site. In a paper submitted on April 29, Zlobin cites the melted appearance of several stones found at the bottom of the Khushmo River as a good argument to “confirm the discovery” of Tunguska meteorite fragments.
According to Natalya Artemyeva of the Russian Academy of Sciences’ Geosphere Dynamics Institute, however, Zlobin’s claim is “ridiculous.”
In an article published May 4 on RIA Novosti, Artemyeva stated “There are many meteorites on Earth. For 100 plus years since the fall of the Tunguska space body, the weight of meteoric dust and small meteorites that have fallen out in that region has exceeded the mass of Tunguska.”
An estimated 100 tons of space debris enters Earth’s atmosphere on a daily basis.
Although Zlobin admits in his submitted paper that “strict confirmation of discovered melted stones as Tunguska meteorites is possible only after attentive chemical analysis of substance,” it seems that he is making rather bold claims based on appearance alone — especially considering the enigmatic and iconic nature of this particular impact event.
“It’s ridiculous,” Artemyeva said. “You can’t say by the appearance of a stone that it’s a meteorite. I don’t think there is ground for scientific discussion here.”
And, according to Artemyeva, even if the stones are found to be actual meteorites, connecting them to the 1908 event will still be a challenge.
Zlobin’s samples, which were in storage until 2008, are still awaiting full chemical analysis.
Last night a bright meteor was spotted up and down the northern mid-Atlantic United States from Maryland to Manhattan to Massachusetts. Streaking across the sky just before 8 p.m. EDT, the fireball was witnessed by thousands — the American Meteor Society alone has so far received over 630 reports on its website from the event. (Update 3/25: The AMS has received now over 1170 reports of the meteor.)
While many false images of the meteor quickly began circulating online, the video above is real — captured from a security camera in Thurmont, MD and uploaded to YouTube by Kim Fox (courtesy of Alan Boyle’s article on NBC News’ Cosmic Log.)
So what’s up with all these meteors lately?
According to NASA meteor specialist Bill Cooke, Friday’s fireball — which has become known as the “Manhattan meteor” — was likely caused by a boulder-sized asteroid about 3 feet (0.9 meters) wide entering Earth’s atmosphere. While bolides of this size sometimes result in meteorites that land on the ground, the last reports of the Manhattan meteor have it miles over the Atlantic… any pieces that survived entry and disintegration probably ended up in the ocean.
Here’s another video of the event from a Massachusetts news station.
And if you’re concerned about an apparent increase in the rate of meteors being spotted around the world, don’t be alarmed. Remember — spring is fireball season, after all.
“We’ve known about this phenomenon for more than 30 years. It’s not only fireballs that are affected. Meteorite falls–space rocks that actually hit the ground–are more common in spring as well.”
– Bill Cooke, NASA’s Meteoroid Environment Center
So keep an eye on the sky over the next few weeks — you never know when we’ll be treated to another show!
There’s been a lot of really incredible videos and images of the meteor that streaked across Russian skies on Feb. 15, 2013… but this isn’t one of them.
I recently spotted it on YouTube, uploaded by several users and claiming to be a crater from the meteorite. Whether done purposely to deceive or just in error, the fact is that this isn’t from that event. Actually it’s not even a meteorite crater at all.
What this video shows is a feature in Derweze, Turkmenistan. It’s the remains of a 1971 drilling project by Soviet geologists. When the ground under their rig collapsed after breaking into an underground cavern full of natural gas, the geologists decided to set the borehole on fire to flare off the gases.
They assumed all the gas would soon burn off and the fire would go out. But it’s still burning today, nearly 42 years later.
The fiery glow from the circular pit has inspired the hole’s local name, “The Door to Hell.” You can find some photos of this infernal feature here.
Anyway, in the nature of not only informing but also preventing the spread of disinformation, hopefully this will help clear up any confusion for those who might run across the same video in coming days. News about the Russian meteor is still — no pun intended — very hot right now, and it’s likely that at least a few fraudulent articles might try to garner some attention.
If you want to see some real videos of the meteor, check out our original breaking news article here and see some photos of an actual resulting crater — icy, not fiery — in a frozen Russian lake here.
In order to not make for more easy hits on the incorrectly-titled video I did not set it to play. If you do still want to watch it, you can find it here.
This just in: reports of bright meteors and loud explosions have been coming from Russia, with the incredible video above showing what appears to be a meteor exploding in the atmosphere on the morning of Friday, Feb. 15.
According to Reuters the objects were seen in the skies over the Chelyabinsk and Sverdlovsk regions.
“Preliminary indications are that it was a meteorite rain,” an emergency official told RIA-Novosti. “We have information about a blast at 10,000-meter (32,800-foot) altitude. It is being verified.” UPDATE: The Russian Academy of Sciences has estimated that the single 10-ton meteor entered the atmosphere at around 54,000 kph (33,000 mph) and disintegrated 30-50 kilometers (18-32 miles) up. Nearly 500 people have been injured, most by broken glass — at least 3 in serious condition. (AP)
Chelyabinsk is 930 miles (1,500 km) east of Moscow, in Russia’s Ural Mountains.
Preliminary reports on RT.com state that the meteorite “crashed into a wall near a zinc factory, disrupting the city’s internet and mobile service.” 150 minor injuries have also been reported from broken glass and debris created by the explosion’s shockwave.
ADDED: More videos below:
Contrails and explosions can be heard here, with breaking glass:
Over a city commercial district:
And yet another dash cam:
Watch the garage door get blown in at the 30-second mark:
Here’s a great summary from Russia Today
This event occurs on the same day that Earth is to be passed at a distance of 27,000 km by the 45-meter-wide asteroid 2012 DA14. Coincidence? Most likely. But – more info as it comes!
Read what Phil Plait has to say about this on his Bad Astronomy blog here.
News source: Reuters. H/T to Matt Arnold.
The largest fragment of meteorite NWA 7325 (Photo © Stefan Ralew / sr-meteorites.de)
Pieces of the Moon and Mars have been found on Earth before, as well as chunks of Vesta and other asteroids, but what about the innermost planet, Mercury? That’s where some researchers think this greenish meteorite may have originated, based on its curious composition and the most recent data from NASA’s MESSENGER spacecraft.
NWA 7325 is the name for a meteorite fall that was spotted in southern Morocco in 2012, comprising 35 fragments totaling about 345 grams. The dark green stones were purchased by meteorite dealer Stefan Ralew (who operates the retail site SR Meteorites) who immediately made note of their deep colors and lustrous, glassy exteriors.
Ralew sent samples of NWA 7325 to researcher Anthony Irving of the University of Washington, a specialist in meteorites of planetary origin. Irving found that the fragments contained surprisingly little iron but considerable amounts of magnesium, aluminum, and calcium silicates — in line with what’s been observed by MESSENGER in the surface crust of Mercury.
And even though the ratio of calcium silicates is higher than what’s found on Mercury today, Irving speculates that the fragments of NWA 7325 could have come from a deeper part of Mercury’s crust, excavated by a powerful impact event and launched into space, eventually finding their way to Earth.
In addition, exposure to solar radiation for an unknown period of time and shock from its formation could have altered the meteorite’s composition somewhat, making it not exactly match up with measurements from MESSENGER. If this is indeed a piece of our Solar System’s innermost planet, it will be the first Mercury meteorite ever confirmed.
But the only way to know for sure, according to Irving’s team’s paper, is further studies on the fragments and, ultimately, sample returns from Mercury.
Irving’s team’s findings on NWA 7325 will be presented at the 44th Lunar and Planetary Science Conference to be held in Houston, TX, on March 18-22. Read more in this Sky & Telescope article by Kelly Beatty.
Inset image: impact craters located within Mercury’s Caloris Basin (NASA/JHUAPL)
Composite-color 3D image of Cornelia crater on Vesta (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)
Ever since arriving at Vesta in July 2011, NASA’s Dawn spacecraft has been capturing high-resolution images of the protoplanet’s surface, revealing a surprisingly varied and complex terrain covered in ridges, hills, grooves and, of course, craters of many different sizes and ages. Many of Vesta’s largest craters exhibit strange dark stains and splotches within and around them, some literally darker than coal. These stains were a puzzle to scientists when they were first seen, but the latest research now confirms that they may actually be the remains of the ancient impacts that caused them: dark deposits left by the myriad of carbon-rich objects that struck Vesta over the past four-and-a-half billion years.
Even though Vesta had a completely molten surface 4.5 billion years ago it’s believed that its crust likely solidified within a few million years, making the 530-km (329-mile) -wide world a literal time capsule for events taking place in the inner Solar System since then… one reason why Vesta was chosen as a target for the Dawn mission.
Using data acquired by Dawn during its year in orbit around Vesta, a team led by researchers from Germany’s Max Planck Institute for Solar System Research and the University of North Dakota investigated the dark material seen lining the edges of large impact basins located on the protoplanet’s southern hemisphere. What they determined was that much of the material was delivered during an initial large, low-velocity impact event 2–3 billion years ago that created the largest basin — Veneneia — and was then partially covered by a later impact that created the smaller basin that’s nearly centered on Vesta’s southern pole — Rheasilva.
“The evidence suggests that the dark material on Vesta is rich in carbonaceous material and was brought there by collisions with smaller asteroids.”
– Vishnu Reddy, lead author, Max Planck Institute for Solar System Research and the University of North Dakota
Dawn framing camera images of dark material on Vesta. (NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)
Subsequent smaller asteroid impacts over the millennia likely brought more carbonaceous material to Vesta’s surface, both delivering it as well as revealing any that may have existed beneath brighter surfaces.
The dark, carbon-rich material observed on Vesta by Dawn also seems to match up with similarly dark clasts found in meteorites that have landed on Earth which are thought to have originated from Vesta.
“Our analysis of the dark material on Vesta and comparisons with laboratory studies of HED meteorites for the first time proves directly that these meteorites are fragments from Vesta,” said Lucille Le Corre from the Max Planck Institute for Solar System Research, another lead author of the study.
If evidence of such collisions between worlds can be found on Vesta, it’s likely that similar events were occurring all across the inner solar system during its early days, providing a clue as to how carbon-rich organic material was delivered to Earth — and possibly Mars as well. Such material — the dark stains we see today lining Vesta’s craters — would have helped form the very building blocks of life on our planet.
The team’s findings were published in the November/December issue of the journal Icarus.
Earlier today, Euronews reported an icy “mega meteorite” fall in a farmer’s field in the Hrira region of Morocco. The farmer found the chunk of supposed space ice and put it in his freezer for later investigation by scientists, who apparently confirmed that it is in fact from space.