June 24, 2024
Two large asteroids will safely pass Earth this week, a rare occurrence perfectly timed to commemorate this year's Asteroid Day. Neither poses any risk to our planet, but one of them was only discovered a week ago, highlighting the need to continue improving our ability to detect potentially hazardous objects in our cosmic neighborhood.
Asteroid 2024 MK is between 120 and 260 m in size and was discovered on 16 June 2024. The asteroid will fly past Earth on 29 June during the height of this year’s Asteroid Day activities.
2024 MK is large for a near-Earth object (NEO) and will pass within 290 000 km of Earth’s surface – roughly 75% of the distance between Earth and the Moon.
There is no risk of 2024 MK impacting Earth. However, an asteroid this size would cause considerable damage if it did, so its discovery just one week before it flies past our planet highlights the ongoing need to improve our ability to detect and monitor potentially hazardous near-Earth objects (NEOs).
Due to its size and proximity, 2024 MK will be observable in clear dark skies on 29 June using a small telescope for amateur astronomers in some parts of the world. Plan your observations using ESA’s NEO toolkit.
Asteroid (415029) 2011 UL21 is the larger of the week’s visitors. At 2310 m across, this asteroid is larger than 99% of all known near-Earth objects. However, it won’t come anywhere near as close to Earth. At its closest point on 27 June, it will still be more than 17 times as far away as the Moon.
This asteroid’s orbit around the Sun is steeply inclined, which is unusual for such a large object. Most large objects in the Solar System, including planets and asteroids, orbit the Sun in or close to the equatorial plane.
This could be the result of gravitational interactions with a large planet like Jupiter. Jupiter can deflect previously safe asteroids inwards towards Earth, so understanding this process is important.
(415029) 2011 UL21 is in an ‘11:34 resonance’ with Earth. It completes 11 orbits about the Sun in almost the exact same amount of time in which Earth completes 34 orbits (i.e. 34 years).
The result is a pleasant repeating pattern when you visualise the asteroid’s location relative to Earth over a period of 34 years while keeping Earth fixed in place.