The ‘potentially dangerous’ monstrous asteroid is the largest seen in years

Astronomers scanning the twilight sky have discovered three previously unknown near-Earth asteroids. One of them is the largest potentially dangerous asteroid discovered in eight years.

It measures about 1.5 kilometers (nearly 1 mile) in diameter and is in an orbit that could, in the future, bring it close enough to Earth to pose a problem.

The other two asteroids have trajectories that are entirely, and safely, closer to the Sun than Earth’s orbit. That doesn’t make their discovery any less exciting, adding to a hard-to-find inventory that will allow us to better characterize the population of near-Earth objects.

Most of the solar system’s minor planets – objects in direct orbit around the Sun that are neither planets nor comets – have been discovered at orbital distances greater than those of Earth. There’s the asteroid belt between Mars and Jupiter, the Kuiper belt beyond Neptune where Pluto resides, and a bunch of other rocks, such as Greek and Trojan asteroids that share planetary orbits.

Few minor planets have been discovered closer to the Sun, and for very good reason. We must look toward a large, bright star, whose blinding light makes small, dark asteroids virtually undetectable. This means that we are more likely to find objects when looking away from the Sun in a direction that faces the outer solar system.

To have a chance of spotting an inner Solar System asteroid, astronomers must wait until the twilight hours at dawn and dusk, when the Sun’s glare is mostly below Earth’s horizon, providing just enough light to illuminate inner asteroids that could sweep through space.

A research team led by astronomer Scott S. Sheppard of the Carnegie Institution for Science has conducted such a search for large parts of the sky closer to the Sun than Earth and Venus, leading to some fascinating discoveries.

One was 2021 PH27, an asteroid with the shortest orbit of any asteroid found to date, at just 113 days. Then there is 2021 LJ4, which also circles the Sun entirely in Earth orbit. Both are known as the Atira asteroids.

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

“There are probably only a few near-Earth asteroids left with similar sizes to be found, and these large undiscovered asteroids likely have orbits that keep them inside the orbits of Earth and Venus most of the time. Only about 25 asteroids with orbits completely within Earth’s orbit have been discovered so far due to the difficulty of observing near the Sun’s glow.”

The third asteroid, 2022 AP7, is known as the Apollo asteroid. These are asteroids that have elliptical trajectories that take them from space closer to the Sun beyond Earth’s orbit. By crossing our orbit, Apollo asteroids like 2022 AP7 could venture close enough to our planet to risk a collision, gaining their a classification of “potentially dangerous”.

There are over 2,000 potentially dangerous asteroids (the largest of which is around 7 kilometers in diameter) that we fortunately know of. If we know them, we can model their orbits and calculate if and when they are likely to be at a dangerous distance from Earth. With enough notice, we might be able to do something, like slam a spacecraft onto their surface to deflect their course.

The discovery of new Atira asteroids is also significant. Our understanding of the population of minor planets in the solar system is primarily based on a census of space rocks in the outermost reaches. Getting a better idea of ​​what’s in the inner solar system can tell us more about the dynamics of the solar system – how asteroids are transported to different regions, as well as more accurate models of how the system evolved over time. over time.

“Our DECam survey is one of the largest and most sensitive searches ever 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.”

Interesting way, despite being more sensitive to small objects, the survey discovered a greater number of larger asteroids – those at least a kilometer in diameter. This could mean that smaller asteroids are less stable in the inner solar system, or more likely to break up in the intense thermal and gravitational environment closer to the Sun.

However, it could just be that smaller asteroids are harder to detect. This is an excellent argument for more sensitive investigations in the future.

The article describing the three asteroids was published in The Astronomical Journal.

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