According to NASA, the JWST sees the universe using infrared radiation, a form of light that we feel as heat and is invisible to human eyes.
NASA and other world-leading space agencies are putting the most powerful eyes in the night sky on asteroid 2024 YR4, a newly discovered threat to Earth.
Asteroid 2024 YR4 was discovered on Dec. 27 using telescopes in Río Hurtado, Chile, part of the NASA-funded Terrestrial-impact Last Alert System (ATLAS) facility.
The discovery set off an automated asteroid warning system, which determined the object has a small chance of hitting Earth on Dec. 22, 2032. The asteroid has been given a Level 3 out of 10 on the Torino Impact Hazard Scale, which is a system used to communicate the potential dangers posed by near-Earth objects.
Over the past week, the chances of the asteroid crashing into Earth have doubled but still remain highly unlikely at just over 2%.
Asteroid 2024 YR4.
(NASA)
An international team of astronomers, including NASA and ESA planetary defense groups, requested time to use the James Webb Space Telescope to study 2024 YR4.
NEWLY DISCOVERED ASTEROID WILL LIKELY MISS EARTH BUT IMPACT DURING 2032 HOLIDAYS CAN’T BE RULED OUT
For about four hours in March, the James Webb Space Telescope will use its Mid-InfaRed Instrument (MIRI) to help astronomers better understand 2024 YR4’s size and overall risk to Earth.
Currently, the asteroid is estimated to be between 130 and 328 feet wide. An asteroid of this size impacts Earth on average every few thousand years and could cause “severe damage” to a local region.
However, astronomers are limited to studying asteroid 2024 YR4 in visible light, which the space rock reflects from the Sun. According to the ESA, the brighter an asteroid, the larger it is, but that also depends on how reflective the surface is.
Near-Earth asteroid 2024 YR4 observed with the European Southern Observatory’s Very Large Telescope in January 2025.
(Credit: ESO/O. Hainaut et al. / FOX Weather)
“It is very important that we improve our size estimate for 2024 YR4: the hazard represented by a 40 meter (130-foot) asteroid is very different from that of a 90 meter (300-foot) asteroid,” the ESA said.
This is where Webb’s MIRI instrument comes in. Astronomers will use observations of the heat emitted by the asteroid, rather than the reflective light. This can offer a better estimate of 2024 YR4’s size, and then NASA, ESA and other organizations can more confidently assess the hazard to Earth.
On the ground, astronomers are studying the asteroid with the European Southern Observatory’s Very Large Telescope in Chile and other telescopes to gather more data. However, the asteroid will fade from Earth’s view over the next few months and won’t become visible again until 2028.