NASA has snapped photos and videos of the two huge asteroids that passed by our planet a few weeks ago.
The two asteroids, 2011 UL21 and 2024 MK, zipped past Earth on June 27 and 29, respectively, and were snapped by NASA's Deep Space Network's Goldstone planetary radar.
While 2011 UL21 soared past us at a distance of 4.1 million miles—around 17 times further away than the moon—2024 MK came within 181,300 miles of our planet, within the 238,900-mile orbit of the moon.
2011 UL21 was much bigger than 2024 MK, with a gargantuan diameter of about a mile. 2024 MK, on the other hand, was estimated to be between 394 and 853 feet across—roughly the same size as the Washington Monument.
2011 UL21 was first spotted by the NASA-funded Catalina Sky Survey in 2011, but this marks the first time it has approached the Earth at such a close distance. Astronomers seized this opportunity to examine the asteroid in more detail, using the Deep Space Network's Goldstone Solar System Radar, and discovered that it actually has a tiny moonlet orbiting it at a distance of about 2 miles.
"It is thought that about two-thirds of asteroids of this size are binary systems, and their discovery is particularly important because we can use measurements of their relative positions to estimate their mutual orbits, masses, and densities, which provide key information about how they may have formed," Lance Benner, principal scientist at JPL, said in a NASA statement.
NASA's Goldstone Solar System Radar was also used to examine 2024 MK as it passed Earth, capturing images of it as it tumbled through space. This allowed the astronomers to spot details of the asteroid's surface, including ridges and enormous boulders. 2024 MK had only been discovered by scientists a mere 13 days before its closest approach to Earth.
"This was an extraordinary opportunity to investigate the physical properties and obtain detailed images of a near-Earth asteroid," said Benner.
Both 2011 UL21 and 2024 MK are classified as near-Earth objects (NEOs) and potentially hazardous asteroids (PHAs) due to their size and how close they got to the Earth. NEOs are defined as any object that approaches within 1.3 astronomical units of the sun (a single AU being the distance from Earth to the sun, or roughly 93 million miles).
PHAs, on the other hand, are defined as coming within 4.6 million miles of Earth's orbit and also being large enough to cause significant damage upon impact. They typically have an absolute magnitude of 22.0 or brighter, which generally corresponds to a diameter of about 460 feet or larger.
Thankfully, neither of these asteroids will pose a threat to our planet any time in the future.
"An asteroid 100-200 m [330-650 feet] in diameter would cause a regional disaster, taking out a small country, but with the resulting global consequences in terms of the global economy and 'globalization,'" Jay Tate, the director of the Spaceguard Centre, an observatory in the United Kingdom, previously told Newsweek.
NASA's Planetary Defense Coordination Office states that "no known asteroid poses a significant risk of impact with Earth over the next 100 years."
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