Post by Andrei Tchentchik on Jul 8, 2019 17:25:28 GMT 2
(.#236).- The comet that will graze the Earth in 2015, looks like a skull.
Comet grazing the Earth for Halloween looks like a skull
By Tristan Vey AFP agence - Updated on 31/10/2015 at 14:58
The asteroid, dubbed "2015 TB145", could be a dead comet, says NASA.
INFOGRAPHY - "The big space rock that will pass near the Earth for Halloween is most likely a dead comet, which strangely and opportunistically looks like a skull," Nasa writes in a statement.
Two dark cavities for the eyes, a round hole in the nose dug on a whitish shaped skull: the photo broadcast by NASA is striking. "The big space rock that will pass near Earth for Halloween is most likely a dead comet, which strangely, and appropriately, resembles a skull," NASA writes in a statement released late Friday. "It looks like she's wearing a skull disguise for Halloween (near the Earth)," NASA scientist Kelly Fast said in the statement.
Astronomers initially thought it was an asteroid when they detected the object in early October, so they named it Asteroid 2015 TB145. But after observing it better with the NASA's Infrared Telescope (IRTF) in Hawaii, they "determined that it is more likely a dead comet that lost its volatile materials after many passes around the sun, "says the space agency.
Saturday, therefore, the day of Halloween, a block several hundred meters in diameter will come close to us. Finally, "graze" ... This large pebble 200 to 400 meters wide, according to estimates, will pass 500 000 km from the Earth, almost one and a half times the distance that separates us from the moon. If this is indeed very close to the scale of the solar system, the risk of collision is perfectly zero. When he goes closer to the planet, at 18 hours, it will not be visible to the naked eye. Not even with the binoculars. But since the season is favorable to play to be afraid on this day of the dead, let's play: could it be that an object of this size hits the Earth one day?
The answer is unambiguous: yes, it is possible. "It is estimated that the fall of an asteroid of a hundred meters must occur once every ten thousand years, explains Patrick Michel, specialist of asteroids at the Observatory of Nice-Côte d'Azur. An estimate derived from the study of impact craters on the Moon. On Earth, the most recent crater in this category is 60,000 years old. But there is a good chance that other asteroids of comparable size have broken down in the oceans in the meantime without leaving a trace. "
Whether such an object falls on land or at sea, there is a good chance that the consequences will be catastrophic. Depending on its speed, density, angle of attack, it could form a crater several kilometers wide and several hundred meters deep, or cause a wave of several hundred meters. The entire surrounding area would be impacted for hundreds of miles around. The death toll is likely to be in the millions, or even tens of millions.
As for objects more than one kilometer in diameter, they would be able to annihilate humanity. Fortunately, they are more rare: it falls only one every 500,000 years. More than 90% of them have already been identified and pose no threat in the medium term.
"If we see dangerous asteroids coming a few years in advance, then it would still be possible to deviate from their trajectory"
On the other hand, only 10 to 15% of asteroids over 150 meters in diameter are known. Our Halloween asteroid - or comet - named 2015 TB145 was only detected on October 10 by the University of Hawaii's Pan-STARRS-1 space telescope. This ignorance is sufficiently disturbing for NASA to have recently undertaken, as part of the SpaceGuard program (literally "guardian of space"), a census of all these objects. Objective: to identify 90% of them by 2025.
It is not excluded that other objects of this type are still discovered only a few weeks before presenting a danger for the Earth. It would then be too late to undertake anything. "But if we see them arrive a few years in advance, then it would still be possible to deviate from their trajectory," says Patrick Michel. The Aida mission, currently under evaluation by the European and American space agencies, is looking very seriously at testing an impactor on an asteroid in 2022.
It would be better if no one had the bad idea to meet us by then. We would then have no solution that has ever been tested, which could seriously complicate political discussions. "But the longest is usually to make a decision," says Patrick Michel philosophically.
In the meantime, astronomers will take advantage of this close flyby of 2015 TB145 to study it closely. It should be possible to obtain radar images with an unprecedented definition of two meters per pixel. A real bargain: the next flyover as close to such a large object is not expected before 2027. Except surprise last minute, obviously.
F I N .
Comet grazing the Earth for Halloween looks like a skull
By Tristan Vey AFP agence - Updated on 31/10/2015 at 14:58
The asteroid, dubbed "2015 TB145", could be a dead comet, says NASA.
INFOGRAPHY - "The big space rock that will pass near the Earth for Halloween is most likely a dead comet, which strangely and opportunistically looks like a skull," Nasa writes in a statement.
Two dark cavities for the eyes, a round hole in the nose dug on a whitish shaped skull: the photo broadcast by NASA is striking. "The big space rock that will pass near Earth for Halloween is most likely a dead comet, which strangely, and appropriately, resembles a skull," NASA writes in a statement released late Friday. "It looks like she's wearing a skull disguise for Halloween (near the Earth)," NASA scientist Kelly Fast said in the statement.
Astronomers initially thought it was an asteroid when they detected the object in early October, so they named it Asteroid 2015 TB145. But after observing it better with the NASA's Infrared Telescope (IRTF) in Hawaii, they "determined that it is more likely a dead comet that lost its volatile materials after many passes around the sun, "says the space agency.
Saturday, therefore, the day of Halloween, a block several hundred meters in diameter will come close to us. Finally, "graze" ... This large pebble 200 to 400 meters wide, according to estimates, will pass 500 000 km from the Earth, almost one and a half times the distance that separates us from the moon. If this is indeed very close to the scale of the solar system, the risk of collision is perfectly zero. When he goes closer to the planet, at 18 hours, it will not be visible to the naked eye. Not even with the binoculars. But since the season is favorable to play to be afraid on this day of the dead, let's play: could it be that an object of this size hits the Earth one day?
The answer is unambiguous: yes, it is possible. "It is estimated that the fall of an asteroid of a hundred meters must occur once every ten thousand years, explains Patrick Michel, specialist of asteroids at the Observatory of Nice-Côte d'Azur. An estimate derived from the study of impact craters on the Moon. On Earth, the most recent crater in this category is 60,000 years old. But there is a good chance that other asteroids of comparable size have broken down in the oceans in the meantime without leaving a trace. "
Whether such an object falls on land or at sea, there is a good chance that the consequences will be catastrophic. Depending on its speed, density, angle of attack, it could form a crater several kilometers wide and several hundred meters deep, or cause a wave of several hundred meters. The entire surrounding area would be impacted for hundreds of miles around. The death toll is likely to be in the millions, or even tens of millions.
As for objects more than one kilometer in diameter, they would be able to annihilate humanity. Fortunately, they are more rare: it falls only one every 500,000 years. More than 90% of them have already been identified and pose no threat in the medium term.
"If we see dangerous asteroids coming a few years in advance, then it would still be possible to deviate from their trajectory"
On the other hand, only 10 to 15% of asteroids over 150 meters in diameter are known. Our Halloween asteroid - or comet - named 2015 TB145 was only detected on October 10 by the University of Hawaii's Pan-STARRS-1 space telescope. This ignorance is sufficiently disturbing for NASA to have recently undertaken, as part of the SpaceGuard program (literally "guardian of space"), a census of all these objects. Objective: to identify 90% of them by 2025.
It is not excluded that other objects of this type are still discovered only a few weeks before presenting a danger for the Earth. It would then be too late to undertake anything. "But if we see them arrive a few years in advance, then it would still be possible to deviate from their trajectory," says Patrick Michel. The Aida mission, currently under evaluation by the European and American space agencies, is looking very seriously at testing an impactor on an asteroid in 2022.
It would be better if no one had the bad idea to meet us by then. We would then have no solution that has ever been tested, which could seriously complicate political discussions. "But the longest is usually to make a decision," says Patrick Michel philosophically.
In the meantime, astronomers will take advantage of this close flyby of 2015 TB145 to study it closely. It should be possible to obtain radar images with an unprecedented definition of two meters per pixel. A real bargain: the next flyover as close to such a large object is not expected before 2027. Except surprise last minute, obviously.
F I N .
