Three plane-sized asteroids—and one the size of a house—are set to pass close by Earth on Thursday, NASA said.
Several asteroids are set to dash past Earth in the coming days, according to a list released by NASA’s Jet Propulsion Laboratory, close encounters that are almost certain to pass harmlessly and come days after the White House announced new plans to defend the planet against threats from space.
Key Facts
Two asteroids, one bus-sized and the other the size of a house, will make relatively close approaches to Earth on Wednesday, according to NASA’s Asteroid Watch Dashboard.
Three more, all approximately airplane-sized, are also set to whizz past Earth on Thursday, the agency said.
While asteroid strikes could wipe out life on Earth, none of those due to pass by in the coming days are on a collision course nor are any big enough to trigger more than a limited disaster if they were to make impact.
NASA considers size and proximity when assessing the risk an asteroid poses and only considers an object a potential threat when it is larger than around 500 feet and will pass within around 4.6 million miles of Earth.
While all will track relatively close to Earth—the nearest will be around 570,000 miles and the farthest 3.85 million miles—these distances are still immense and there is no significant risk of impact, all passing by at a distance much further than that between Earth and the moon.
None of the asteroids come close to reaching the size NASA considers a threat either—the largest is approximately 150 feet and the smallest just 35 feet—so even if they would be on track to hit Earth, two would likely harmlessly burn up in the atmosphere and three likely to cause only limited local damage around any impact site.
New strategy
The cluster of near misses comes days after the White House announced a new strategy to help “detect, prepare for, and thwart near-Earth object hazards.” It outlined six key goals for the coming decade, including boosting efforts to detect potentially risky space objects, bolstering international cooperation on the matter and developing the means to fend off any potential threat. The policy follows the early successes of NASA’s asteroid-deflecting mission, DART, which altered the trajectory of an asteroid last year by ramming it with a spacecraft.
Key Background
Asteroids are essentially space rocks orbiting the sun. They are remnants from the building materials left over from the formation of the sun, planets and other parts of the solar system and are largely clustered between Mars and Jupiter.
Given our understanding of physics, scientists are able to predict the movements of known asteroids to high degrees of accuracy over long periods of time. NASA says no asteroid poses a significant risk of hitting Earth within the next 100 years and the highest risk for a known asteroid is a 1 in 714 chance slated for 2185, less than 0.2%. Detection is imperfect, however, and many go undetected, with NASA estimating it is only aware of around 40% of the objects that could wipe out a city the size of New York.
Big Number
1,278,331. That’s how many known asteroids there are, according to NASA. The largest, Vesta, is around 329 miles in diameter and some are as small as 33 feet across. Overall, the total mass of all known asteroids combined is less than the mass of Earth’s Moon.
This article was first published on forbes.com
