"This month, some big space rocks have been hitting Earth's atmosphere. There have been five or six notable fireballs that might have dropped meteorites around the United States." It’s not the number of fireballs that has researchers puzzled. So far, fireball counts in February 2012 are about normal. Instead, it's the appearance and trajectory of the fireballs that sets them apart.
"These fireballs are particularly slow and penetrating. They hit the top of the atmosphere moving slower than 15 km/s, decelerate rapidly, and make it to within 50 km of Earth’s surface." The action began on the evening of February 1st when a fireball over central Texas wowed thousands of onlookers in the Dallas-Fort Worth area.
"It was brighter and long-lasting than anything I've seen before. The fireball took about 8 seconds to cross the sky. I could see the fireball start to slow down; then it exploded like a firecracker artillery shell into several pieces, flickered a few more times and then slowly burned out." Another observer in Coppell, Texas, reported a loud double boom as "the object broke into two major chunks with many smaller pieces." The fireball was bright enough to be seen on NASA cameras located in New Mexico more than 500 miles away. "It was about as bright as the full Moon." Estimates are that the object was 1 to 2 meters in diameter.
So far in February, NASA's All-Sky Fireball Network has photographed about a half a dozen bright meteors that belong to this oddball category. They range in size from basketballs to buses, and all share the same slow entry speed and deep atmospheric penetration. A scientist has analyzed their orbits and come to a surprising conclusion: "They all hail from the asteroid belt - but not from a single location in the asteroid belt. There is no common source for these fireballs, which is puzzling."
This isn't the first time sky watchers have noticed odd fireballs in February. In fact, the "Fireballs of February" are a bit of a legend in meteor circles. "Back in the 1960s and 70s, amateur astronomers noticed an increase in the number of bright, sound-producing deep-penetrating fireballs during the month of February. The numbers seemed significant, especially when you consider that there are few people outside at night in winter. Follow-up studies in the late 1980s suggested no big increase in the rate of February fireballs. Nevertheless, we've always wondered if something was going on." Indeed, a 1990 study suggests that the 'February Fireballs' are real. They analyzed photographic records of about a thousand fireballs from the 1970s and 80s and found evidence for a fireball stream intersecting Earth's orbit in February.They allso found signs of fireball streams in late summer and fall. The results are controversial, however.
NASA's growing All-Sky Fireball Network could end up solving the mystery. They are adding cameras all the time, spreading the network's coverage across North America for a dense, uninterrupted sampling of the night sky. "The beauty of our smart multi-camera system, is that it measures orbits almost instantly. We know right away when a fireball flurry is underway - and we can tell where the meteoroids came from." This kind of instant data is almost unprecedented in meteor science, and promises new insights into the origin of February’s fireballs. Meanwhile, the month isn't over yet. "If the cows and dogs start raising a ruckus tonight, go out and take a look." (video)
and let those few be well tried
before you give them your confidence. **
George Washington
LARGEST QUAKES -
This morning -
5.2 FIJI REGION
Yesterday -
2/22/12 -
5.1 OFF W COAST OF NORTHERN SUMATRA
5.5 KEPULAUAN KAI, INDONESIA
5.2 VANUATU
VOLCANOES -
Chilean volcano's ash is still disrupting ecosystems - Nine months after the eruption of the Puyehue volcano in Chile forced thousands to flee for their lives, its impact is still being felt in the surrounding region. Puyehue, located in the southern Chilean Andes, began erupting on 3 June 2011.
TSUNAMI / FREAK WAVES / ABNORMAL TIDES -
Almost a year after the Japanese Tohoku earthquake and mega-tsunami, the Pacific Ocean is still dealing with the consequences of the catastrophe. A mass of debris was washed out to sea as floodwaters receded from the land, and some of that wreckage continues to float around the ocean. Most of it headed eastwards, according to modelling work by the Hawaii-based International Pacific Research Center. "So far, the debris field has spread in length more than 2,000 nautical miles, and is more than 1,000 nautical miles wide." That is approaching 4,000km by 2,000km.
Japanese estimates suggested perhaps 20 million tonnes of debris were generated by the earthquake and the incoming rush of water on 11 March last year. Most would have stayed on land, and a fair proportion pulled out to sea would have sunk rapidly. But it is possible a million tonnes is still floating on the ocean. Video pictures at the time showed all manner of materials caught in the flow, from upturned boats and cars to whole buildings picked up off their foundations. The dominant movement of water off Japan is the Kuroshio Current, the North Pacific equivalent of the Gulf Stream in the Atlantic. It hugs the Asian continental slope until about 35 degrees North, where it is then deflected due east into the deep ocean as the Kuroshio Extension. A lot of the floating material rode this extension.
What a simulation shows is the area of ocean where debris might be found, but look over the side of any ship and you would very probably see no debris at all because the individual items have now become widely separated. However, the information is of immense interest to shipping authorities because objects in the water, depending of their size, can be a serious collision hazard. Another keenly interested party is the Papahanaumokuakea Marine National Monument, the marine park encompassing the northwestern Hawaiian islands and atolls, such as Midway. It is an area of outstanding natural beauty and is home to many interesting and endangered species. So far, the modelling has suggested the bulk of the field is passing to the north of the monument. "However, the currents have changed and so we expect reports [of debris washing up] from Midway and the Kure Atoll soon." The debris may touch the west coast of the US in another year or two, but what does make landfall will be a small percentage of the overall floating mass. Ultimately, the IPRC work suggests, at least 95% of the debris that has not sunk will move into the North Pacific "Garbage Patch", a long-lived circulation of floating rubbish trapped by the North Pacific Gyre. Over time it will decay and sink. The concern for conservationists is that smaller, particularly plastic fragments can be ingested by marine organisms. (Animation of how the Japanese tsunami debris field has spread since March 2011)
TROPICAL STORMS -
No current tropical storms.
