Two large asteroids passed by the Earth only 42 hours apart (one of them was discovered a week ago and will pass today)

The asteroids, which are about 2 km in diameter, passed one on June 27 and one today, June 29, did not endanger the Earth. One of them was discovered only a week ago, which turns on a red light. Tomorrow, June 30, will be International Asteroid Day

Two asteroids, including the newly identified 2024 MK, passed safely by Earth this week, in a coincidence reminiscent of Asteroid Day. The event highlights efforts such as the European Space Agency's Asteroid Deflection Mission and their new Flyeye telescope system designed to improve our ability to detect and respond to these celestial threats.

Approaching asteroid 2024 MK

2024 MK – less than two weeks between discovery and transition

Asteroid 2024 MK between 120 and 260 meters (400 to 850 feet) in diameter was discovered on June 16, 2024. The asteroid will pass by Earth on June 29 during this year's Asteroid Day peak.

2024 MK is relatively large for a near-Earth object (NEO) and will pass about 290,000 km (180,000 miles) from Earth – about 75% of the distance between Earth and the Moon.

There is no danger that asteroid 2024 MK will collide with Earth. However, an asteroid of this size would have caused significant damage if it collided, so its discovery just a week before it passed by our planet highlights the ongoing need to improve our ability to detect and track near-Earth objects.

Due to its size and proximity, 2024 MK will be viewable in dark, clear skies on June 29 with a small telescope for amateur astronomers in some parts of the world. Plan your observations using ESA's NEO toolkit.

Approaching asteroid (415029) 2011 UL21 - among the largest known

Asteroid (415029) 2011 UL21 passed by Earth on June 27 at 20:14 UTC (22:14 CEST). At 2310 meters in diameter, it is larger than 99% of all known near-Earth objects, but it poses no risk to Earth and will pass at more than 17 times the distance of the Moon.

Asteroid (415029) 2011 UL21 is the largest of this week's visitors. With a diameter of 2310 meters (7600 feet), this asteroid is larger than 99% of all known near-Earth objects. However, it will not come close to Earth. At its closest point on June 27, it will still be more than 17 times the distance to the moon.

The 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 at or near the equator.

Asteroid (415029) 2011 UL21 passes by Earth

Asteroid (415029) 2011 UL21 will pass by Earth on June 27 at 20:14 UTC (22:14 CEST). With a diameter of 2310 meters, it is larger than 99% of all near-Earth objects (NEOs), but it poses no risk to Earth and will pass at more than 17 times the distance to the Moon.

Asteroid (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 (that is, 34 years).

The result is a pleasant periodic pattern when illustrating the position of the asteroid relative to the Earth over a period of 34 years while keeping the Earth fixed in place.

Asteroid Day 2024

The many craters on the Earth's surface are evidence of asteroid impacts that greatly influenced the history and development of our planet.

Asteroid Day, observed annually on June 30, is sponsored by the United Nations. This date marks the largest observed asteroid impact in recorded history – the aerial explosion over Tunguska in isolated Siberia in 1908, which felled approximately 80 million trees.

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

Later this year ESA's Hera mission will be launched as part of the world's first asteroid deflection experiment. Hera will conduct a detailed survey of the dimorphous asteroid after NASA's DART mission hits in September 2022 and help turn the experiment into an understandable and reproducible planetary defense technique.

Now, ESA is developing a network of insect-inspired Flyeye telescopes that will scan the entire sky every night in search of potentially dangerous asteroids.

ESA's future NEOMIR satellite will be positioned between the Earth and the Sun and will use infrared light to detect asteroids approaching our planet from areas of the sky that cannot be observed from the ground.

• Over 1,100 supernovae and 50 near-Earth objects have been discovered through a new survey
• Ten thousand near-Earth objects have been discovered
• SIMONE - the European program for the study of near-Earth objects