Near-Earth ‘planet-killer’ asteroid spotted, largest in 8 years

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Astronomers have spotted three near-Earth asteroids lurking undetected in the sun’s glare. One of the asteroids is the largest potentially Earth-hazardous object discovered in the past eight years.

Asteroids belong to a group found in the orbits of Earth and Venus, but they are incredibly difficult to observe because the brightness of the sun shields them from telescope observations.

To avoid sun glare, astronomers jumped at the chance to conduct their observations during the brief twilight window. An international team spied on space rocks while using the dark energy camera on the 4-meter Víctor M. Blanco Telescope located at the Cerro Tololo Inter-American Observatory in Chile.

Their findings published Monday in The Astronomical Journal.

One of the asteroids, called 2022 AP7, is 1.5 kilometers (0.9 miles) wide and has an orbit that could bring it back on Earth’s path in the future, but it’s hard for scientists to predict. know when.

“Our twilight survey scours the area inside the orbits of Earth and Venus in search of asteroids,” said study lead author Scott S. Sheppard, an astronomer at the Earth & Planets Laboratory. the Carnegie Institution for Science, in a statement.

“So far we’ve found two large near-Earth asteroids about 1 kilometer in diameter, a size we call planet killers.”

The other two asteroids, 2021 LJ4 and 2021 PH27, are in much safer orbits that pose no risk to Earth.

Astronomers are intrigued by 2021 PH27, however, because it is the closest known asteroid to the sun. As space rock gets closer to our star, its surface reaches temperatures hot enough to melt lead.

Asteroid-hunting astronomers face a daunting challenge if they want to find space rocks in the inner solar system – which includes Mercury, Venus, Earth, Mars and the main asteroid belt. In order to avoid harsh sunlight, they only have two 10-minute windows each night to scan the area with ground-based telescopes.

At dusk, astronomers still face the complications of a bright sky in the background due to the sun. And to explore the inner solar system, their telescopes must focus near the horizon, which means they must peer through Earth’s thick, blurry atmosphere.

While things seem complicated for ground-based telescopes, observations of the inner solar system are impossible for space telescopes like Hubble and James Webb because the heat and intense sunlight could fry their instruments, which is why the two observatories spacecraft are pointed away from the star.

The wide-field capability of the Dark Energy Camera helped astronomers overcome their observational challenges and they were able to scan large areas of the night sky in detail.

“Large areas of sky are needed because interior asteroids are rare, and deep images are needed because asteroids are faint and you’re fighting the bright twilight sky near the Sun as well as the distorting effect of Earth’s atmosphere,” Sheppard said. “DECam can cover large areas of the sky at depths impossible to reach with smaller telescopes, allowing us to reach further, cover more sky, and probe the inner solar system in ways never before possible. .”

Near-Earth objects are asteroids and comets whose orbit places them within 48.3 million kilometers of Earth. Detecting the threat of near-Earth objects with the potential to cause serious damage is one of the primary goals of NASA and other space organizations around the world.

No asteroids are currently on a direct impact path with Earth, but more than 27,000 near-Earth asteroids exist in all shapes and sizes.

While NASA has recently proven that it can successfully change the motion of an asteroid in space With September’s Double Asteroid Redirection Test, or DART mission, astronomers must first find space rocks that pose a threat to our planet. Instruments like the Dark Energy Camera, as well as future space observatories like the Near-Earth Object Surveyorcan locate previously unknown asteroids.

Studying and understanding asteroid populations will also help scientists understand the distribution and dynamics of space rocks, such as how the sun’s heat can fracture and fragment them over time.

“Our DECam survey is one of the largest and most sensitive searches ever done for objects in Earth’s orbit and near the orbit of Venus,” Sheppard said. “It’s a unique chance to understand what kinds of objects lurk in the inner solar system.”

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