The Asteroid 2024 YR4: Is Gran Telescopio Canarias tracking it up?

In recent months, many clients, enthusiasts, and followers of Astrolapalma have asked us if any of the telescopes in La Palma—especially the Gran Telescopio Canarias (GTC)—are observing a potentially hazardous asteroid. The answer is yes: scientists from the Instituto de Astrofísica de Canarias (IAC), together with international collaborators, are closely monitoring asteroid 2024 YR4, a recently added object to the European Space Agency’s (ESA) impact risk list.

Asteroid 2024 YR4: What Do We Know?

Asteroid 2024 YR4 was discovered on December 28, 2024, by the Pan-STARRS 2 telescope in Hawaii. It is a Near-Earth Object (NEO) belonging to the Aten group, characterized by orbits that cross Earth’s path. Its estimated size ranges between 38 and 85 meters in diameter, depending on its reflectivity (albedo).

During the early months of 2025, uncertainty about its orbital path led to its inclusion in ESA’s CLOMON risk list.

Why Is This Important?

In February 2025, initial observations estimated a 3.1% probability that 2024 YR4 could impact Earth on November 27, 2032. This was the highest probability recorded for an object of this type, triggering international observation protocols. However, thanks to new data gathered by telescopes worldwide—including some from La Palma—this probability has drastically dropped to below 0.004%.

New simulations have revealed an unexpected development: the probability of an impact with the Moon is now estimated at 4.3%, based on analyses using data from NASA’s James Webb Space Telescope and the NASA Scout system. While still relatively low, this value is significant enough to justify ongoing monitoring.

Monitoring from the Roque de los Muchachos Observatory

Since early 2025, the IAC has led an intensive observation program at the Roque de los Muchachos Observatory in La Palma to refine the orbit of 2024 YR4. The telescopes involved include:

• Nordic Optical Telescope (NOT)

• Liverpool Telescope

• Isaac Newton Telescope (INT)

These instruments have enabled high-precision astrometry, improving orbital parameters and significantly reducing trajectory uncertainties.

Is the Gran Telescopio Canarias Involved?

The Gran Telescopio Canarias (GTC) has not yet participated directly in tracking 2024 YR4, as the asteroid’s brightness has been too low for its instruments, which are optimized for observing very distant objects. Nevertheless, the GTC will play a crucial role in future spectroscopic observation campaigns, allowing scientists to analyze the asteroid’s composition and assess the type of impact it could produce in case of a collision, whether with Earth or the Moon.

When Will 2024 YR4 Be Observed Again?

Currently, the asteroid is not observable due to its position in the sky and faint apparent magnitude. It is expected to become visible again during key windows before 2032, especially in 2028 and 2031, when it can be observed both to refine its orbit and to characterize its surface.

La Palma Observatory in Planetary Defense

The monitoring of 2024 YR4 confirms once again the key role of the Roque de los Muchachos Observatory as a strategic facility for sky surveillance and planetary defense. Its observational capabilities and international collaboration make it a fundamental part of the global scientific network monitoring potential space threats.

Conclusion: Canary Islands Science Serving Earth… and the Moon

Although asteroid 2024 YR4 no longer poses a significant threat to Earth, its possible impact with the Moon maintains scientific interest and active monitoring. The work led from La Palma shows how astrophysical research not only helps us better understand the universe but also contributes to planetary safety. At Astrolapalma, we will continue to share these developments with clarity, enthusiasm, and rigor.

IAC news on the tracking of 2024 YR4:
https://www.iac.es/en/outreach/news/iac-continues-track-asteroid-2024-yr4-refine-probability-impact-2032

Official MPC page for asteroid 2024 YR4 (if available):
https://www.minorplanetcenter.net/db_search