This animation demonstrates why the asteroid 2024 YR4 was only discovered two days after it passed Earth in December 2024, and why we will have to wait three years to know for certain whether it will impact the Moon on 22 December 2032.
2024 YR4 approached Earth from the day side of the planet, from a region of the sky hidden by the bright light of the Sun. This region is a significant blind spot for our current asteroid warning systems.
In mid-2025, it faded from view from humankind’s most powerful telescopes. While astronomers were able to study the asteroid for long enough to rule out an Earth impact in 2032, it was left with a 4% chance of impacting the Moon.
The orbits of Earth and 2024 YR4 line up every four years, and so we must now wait until mid-2028 for astronomers to continue studying its trajectory. When the asteroid returns into view, they will be able to confirm, or much more likely, rule out a lunar impact in 2032.
The yellow area represents the region where the brightness of the Sun makes it impossible to observe an asteroid. The blue area represents the region in which it is possible to observe an asteroid. The black area represents the region in which an asteroid is too faint to observe. The exact shape and size of these areas depends on the telescope being used. The regions shown here are representative of a generic, powerful, Earth-based, optical telescope. The red line indicates the trajectory of asteroid 2024 YR4 during three encounters with Earth in 2024, 2028 and 2032.
The animation was created using the Synodic Orbit Visualisation Tool developed by ESA’s Near-Earth Object Coordination Centre. The tool allows users to visualise the orbits of near-Earth objects (NEOs) in a rotating reference frame that keeps a line connecting Earth and the Sun fixed in place. The primary purpose of the tool is to help users determine when and how an NEO will be visible from Earth.