Astronomers next month will be utilizing NASA's James Webb Space Telescope to better observe an asteroid the size of a football field orbiting the solar system that has a slight chance of colliding with Earth around Christmas Day in 2032.
The Asteroid Terrestrial-Impact Last Alert System telescope located in Rio Hurtado, Chile, first spotted the asteroid, named 2024 YR4, on Dec. 27. It is one of many asteroid discovery programs funded by NASA to scan the solar system in search of near-Earth asteroids.
At the time, NASA said the asteroid, believed to have a width of 131 feet to 295 feet, had a 1.2% chance of striking Earth on Dec. 22, 2032. The probability has now increased to 2.1%, according to the Center for Near Earth Object Studies at NASA's Jet Propulsion Laboratory.
"The chance of impact is very slim, and the asteroid is small enough that the effects of any potential impact would be on a local scale, but the situation is significant enough to warrant the attention of the global planetary defense community," the European Space Agency said Tuesday in a news release.
NASA said in a news release Feb. 7 that ongoing observations from ground-based telescopes involved with the International Asteroid Warning Network will continue while the asteroid is still visible through April, after which it will be too faint to observe until about June 2028.
Astronomers are limited to studying the asteroid through the visible light it reflects from the sun. Generally, the brighter the asteroid, the larger it is, but the relationship strongly depends on how reflective the asteroid's surface is. The hazard represented by a 131-foot-wide asteroid is very different from that of a 295-foot-wide asteroid, according to the ESA.
The James Webb Telescope, which is about 1 million miles away from the Earth as it orbits the sun, is the largest and most powerful telescope ever launched into space. It is able to study infrared light that 2024 YR4 emits rather than the visible light the asteroid reflects. Infrared observations can offer a much better estimate of an asteroid's size, according to a report in Nature published in December.
Astronomers will use Webb's mid-infrared instrument to get a more precise estimate of the asteroid's size, enabling NASA, the ESA, and other organizations to assess any potential hazards and determine any necessary response more confidently.
The first round of observations will take place in early March, just as the asteroid becomes observable by Webb and is at its brightest, according to the ESA, and the second round will take place in May. Astronomers will use these observations to study how the temperature of 2024 YR4 has changed as it moves farther away from the Sun and to provide the final measurements of the asteroid's orbit until it returns into view in 2028.
On NASA's Torino Impact Hazard Scale, 2024 YR4 is rated a 3 out of 10, with 10 being an asteroid "capable of causing global climatic catastrophe that may threaten the future of civilization."
A rating of 3 is classified as "a close encounter, meriting attention by astronomers. Current calculations give a 1% or greater chance of collision capable of localized destruction. Most likely, new telescopic observations will lead to reassignment to Level 0. Attention by public and by public officials is merited if the encounter is less than a decade away."
"As more observations of the asteroid's orbit are obtained, its impact probability will become better known," NASA said. "It is possible that asteroid 2024 YR4 will be ruled out as an impact hazard, as has happened with many other objects that have previously appeared on NASA's asteroid risk list. … It is also possible its impact probability will continue to rise."