For a long time, the glare of the sun had been hiding a secret – three space rocks with one member that could one day be dangerous for the planet. A new study reveals that of the three asteroids recently discovered by astronomers, two are so massive that they have been described as “planet killers” – and one has the ability to cross Earth’s orbit.

Scientists say the region between the orbits of Earth and Venus is often hidden by glare from the Sun, making it difficult for astronomers to observe what may be lurking in the region. But recently, astronomers have been able to overcome the challenge by conducting surveys through two 10-minute windows at night.

And what they found was worth the wait. Three near-Earth asteroids were hidden behind this glow, which means gravity has pushed them into orbits that “allow them to enter Earth’s neighborhood,” according to NASA’s Center for Near-Earth Object Studies.

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Observations of the aurora using the US Department of Energy’s Dark Energy Camera at NOIRLab’s Cerro Tololo Inter-American Observatory in Chile enabled astronomers to spot three Near-Earth Asteroids (NEAs) hiding in the glare of the Sun.

DOE / FNAL / DECam / CTIO / NOIRLab / NSF / AURA / J. da Silva / Spaceengine


The three asteroids have been named 2021 LJ4, 2021 PH27, and 2022 AP7. The first of the three is small, in a safe orbit, and “completely within Earth’s orbit.” About 25 asteroids with this type of orbit have been discovered so far, astronomers said in a press release, due to the Sun. The 2021 PH27 is in this category as well, with one distinction – it’s much larger.

2021 PH27 is between 0.9 and 1.7 kilometers (0.5 to 1 mi) in diameter and is the closest known asteroid to the Sun, according to a press release from Noir Lab, making its surface so hot that it can melt lead. In their study, researchers said there are “likely several” other asteroids of this size and type within the region.

“Our aurora survey scours the region within the orbits of Earth and Venus in search of asteroids,” said astronomer Scott Sheppard, lead author of the new study. “So far we have found two large asteroids near Earth that are about one kilometer in diameter, a size we call planetary killers.”

The third and final newly discovered asteroid is 2022 AP7, and unlike its other three members, it has the potential to inflict an even stronger blow to the planet. This asteroid is larger than 2021 PH27, with a diameter of just under one mile. It’s an Apollo asteroid, which means it has a trajectory in orbit that might one day force it to contact Earth.

It’s also the largest potentially hazardous object on the planet discovered in about eight years, the researchers said.

“Over time, this asteroid will get brighter and brighter in the sky as it begins to cross Earth’s orbit near the actual Earth,” Sheppard told The New York Times. “…This is what we call a planet killer. If this planet collides with Earth, it will cause planet-wide destruction. And that would be very bad for life as we know it.”

But planetary scientist Tracy Baker told The Times that such an incident in the “foreseeable future” has a “very low probability”.

And now, the search for more asteroids continues with the Dark Energy Camera (DECam), which uses high-sensitivity, high-performance technology to capture vast swaths of the sky.

“Large expanses of sky are needed because inner asteroids are rare, and deep images are needed because asteroids are faint and you counteract bright twilight skies near the sun as well as the distorting influence of Earth’s atmosphere,” Sheppard told the press. Release. “DECam can cover large areas of the sky to depths unattainable on smaller telescopes, allowing us to go deeper, cover more of the sky, and explore the inner solar system in ways never done before.”

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