Two Large Asteroids Will Safely Pass Earth Just 42 Hours Apart
One Was Discovered Only a Week Ago
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 (415029) 2011 UL21, the larger of the week’s visitors at 2310 m across, is larger than 99% of all known near-Earth objects. At its closest point on June 27, 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).
Asteroid 2024 MK is between 120 and 260 meters (≈400-850 feet) in size and was discovered on June 16. The asteroid will fly past Earth on June 29 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 (≈180,000 miles) 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 June 29 using a small telescope for amateur astronomers in some parts of the world. Plan your observations using ESA’s NEO toolkit.
The UN-endorsed Asteroid Day commemorates the largest observed asteroid strike in recorded history – the 1908 airburst above Tunguska in largely deserted Siberia, which felled around 80 million trees.
This represented a lucky escape for Europe: it happened just a short rotation of Earth away from affecting the continent’s more heavily populated regions.