Two large asteroids safely pass Earth just 42 hours apart

2024 MK – less than two weeks between discovery and flyby

Asteroid 2024 MK is between 120 and 260 m in size and was discovered on June 16, 2024. The asteroid will fly past Earth on June 29, the peak of this year’s Asteroid Day activities.

2024 MK is large for a near-Earth object (NEO) and will fly within 290,000 km of the Earth’s surface – roughly 75% of the distance between the Earth and the Moon.

There is no risk of 2024 MK impacting Earth. However, an asteroid of this size would cause significant damage if it did, so its discovery just a week before it will fly past our planet highlights the continued need to improve our ability to detect and monitor potentially dangerous near-Earth objects (NEOs).

Because of its size and proximity, 2024 MK will be observable in a clear dark sky on June 29 with a small telescope for amateur astronomers in some parts of the world. Plan your observations with the NEO ESA toolkit.

(415029) 2011 UL21 – Larger than 99% of near-Earth asteroids

Asteroid (415029) 2011 UL21 is the largest of the week’s visitors. With a diameter of 2310 m, this asteroid is larger than 99% of all known near-Earth objects. However, it will not come that close to Earth. 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 near the equatorial plane.

This could be the result of gravitational interactions with a large planet like Jupiter. Jupiter can deflect previously safe asteroids towards Earth, so understanding this process is important.

(415029) 2011 UL21 is in “11:34 resonance” with Earth. It completes 11 revolutions around the Sun in almost exactly the same time it takes Earth to complete 34 revolutions (ie 34 years).

The result is a nice repeating pattern when you visualize the asteroid’s position relative to Earth over a period of 34 years while holding the Earth in place.

Asteroid Day 2024

Impact craters scarred on the Earth’s surface are evidence of how asteroids significantly influenced the history and development of our planet.

The UN-sponsored Asteroid Day commemorates the largest observed asteroid strike in recorded history – the 1908 aerial explosion over Tunguska in largely deserted Siberia that felled some 80 million trees.

For Europe, this represented a lucky escape: it happened only by a short rotation of the Earth, which did not affect the more densely populated areas of the continent.

Through the cooperation and support of its Member States, ESA is uniquely positioned to coordinate the data, information and expertise needed to understand and respond to the asteroid threat in Europe and to participate in humanity’s wider efforts to protect the planet.

Over the past two decades, ESA has been conducting detection and analysis of potentially dangerous NEOs. There are an estimated 5 million NEOs out there larger than 20 m – the threshold above which an impact could cause damage to the ground.

ESA increases asteroid activity

ESA’s Planetary Defense Office is conducting a number of projects aimed at improving our ability to detect, track and mitigate potentially hazardous asteroids.

Launched later this year, ESA’s Hera mission is part of the world’s first asteroid deflection test. Hera will conduct a detailed post-impact survey of the asteroid Dimorphos after the impact of NASA’s DART mission in September 2022 and help turn the experiment into a well-understood and repeatable planetary defense technique. Members of the Hera team will be attending Asteroid Day celebrations later this week.

Back on Earth, ESA is developing a network of insect-inspired Flyeye telescopes that will use their uniquely wide field of view to automatically scan the entire sky each night in search of new potentially dangerous asteroids.

Our future NEOMIR satellite will be located between the Earth and the Sun. Using infrared light, it will detect asteroids approaching our planet from areas of the sky that cannot be seen from Earth because they are obscured by the glow of our star.

Meanwhile, the Office of Planetary Defense continues to keep a close eye on the skies today. ESA’s fireball camera in Cáceres, Spain captured a stunning meteor on the night of 18-19 May 2024, believed to be a small piece of a comet that flew over Spain and Portugal at around 100,000 mph (162,000 km/h) before burning up. over the Atlantic Ocean.

Just a few weeks later, on June 6, 2024, the Catalina Sky Survey in Arizona, USA, discovered a small 2–4 m asteroid that triggered an alert from ESA’s Near Impact Monitoring System (meerkat). That warning wasn’t about a crash, but a very close call. A few hours later, the object flew by the Catalina Sky Survey telescope, which spotted it at a distance of just 1,750 km, making it the second closest flyby of a known, non-falling asteroid ever.