Two large asteroids pass Earth safely just 42 hours apart

2024 MK – less than two weeks from discovery to flyby

Asteroid 2024 MK measures between 120 and 260 m and was discovered on June 16, 2024. The asteroid will fly by Earth on June 29, at 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, or about 75% of the distance between Earth and the Moon.

There is no risk that 2024 MK will impact Earth. However, an asteroid of this size would cause considerable damage if it occurred. Its discovery, just a week before its flyby of our planet, highlights the continued need to improve our ability to detect and monitor potentially dangerous 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 or good binoculars for amateur astronomers in some parts of the world. Plan your observations using ESA’s NEO toolbox.

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

Asteroid (415029) 2011 UL21 is the largest visitor of the week. At 2,310 m in diameter, this asteroid is larger than 99% of all known near-Earth objects (NEOs). However, it won’t come that close to Earth. At its closest point on June 27, it will still be more than 17 times farther away than the Moon.

This asteroid’s orbit around the Sun is highly 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 toward Earth, so it is important to understand this process.

(415029) 2011 UL21 is in “11:34 resonance” with Earth. It completes 11 revolutions around the Sun in almost the same time as the Earth completes 34 revolutions (or 34 years).

The result is a pleasing repeating pattern as you view the asteroid’s location relative to Earth over a 34-year period while keeping Earth fixed in place.

Asteroid Day 2024

The impact craters that mark the Earth’s surface provide evidence of how asteroids have greatly influenced the history and development of our planet.

Asteroid Day, approved by the United Nations, commemorates the largest observed asteroid strike in history: the 1908 aerial explosion over Tunguska, in largely deserted Siberia, which brought down about 80 million trees.

This represented a lucky escape for Europe: it occurred only a short rotation of the Earth before affecting the continent’s most populated regions.

ESA is uniquely positioned, with the cooperation and support of its Member States, to coordinate the data, information and expertise needed to understand and respond to asteroid risks in Europe and to participate in broader efforts to planetary defense of humanity.

Over the past two decades, ESA has carried out the detection and analysis of potentially dangerous near-Earth objects. It is estimated that there are around 5 million near-Earth objects measuring more than 20 m, the threshold above which an impact could cause damage to the ground.

ESA accelerates its activities on asteroids

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

Launching later this year, ESA’s Hera mission is part of the world’s first test of an asteroid deflection. Hera will perform a detailed post-impact study of the Dimorphos asteroid following NASA’s DART mission impact in September 2022 and help transform the experiment into a well-understood and repeatable planetary defense technique. Team Hera members will participate in Asteroid Day celebrations later this week.

Back on Earth, the ESA is developing an array of insect-inspired Flyeye telescopes that will use their unique field of view to automatically scan the entire sky each night for new, potentially dangerous asteroids.

Our future NEOMIR satellite will be located between the Earth and the Sun. It will use infrared light to spot asteroids approaching our planet from regions of the sky that cannot be seen from the ground because they are obscured by the glare of our star.

Meanwhile, the Planetary Defense Office continues to closely monitor the skies today. ESA’s fireball camera in Cáceres, Spain, captured a stunning meteor on the night of May 18-19, 2024. It is believed to have been a small piece of a comet that flew past Spain and Portugal at around 162,000 km/h before bursting into flames. above the Atlantic Ocean.

A few weeks later, on June 6, 2024, the Catalina Sky Survey in Arizona, United States, discovered a small asteroid measuring between 2 and 4 m which triggered an alert from the ESA’s Imminent Impact Monitoring System (Meerkat). This alert was not about an impact, but a very close call. Hours later, the object flew past the Catalina Sky Survey telescope which discovered it at a distance of just 1,750 km, making it the second closest pass by an asteroid without a known impact.