Monster Asteroid Largest Seen in Years

A monster asteroid, possibly the largest seen in eight years, has been discovered by astronomers, and it poses a significant potential hazard.

Gazing into the twilight sky, astronomers found three near-Earth asteroids previously unknown. The largest measures approximately 1.5 kilometers (nearly 1 mile) across.

Although the other two asteroids are believed to have paths closer to the Sun than the Earth’s orbit, the monster asteroid is in an orbit that may, in the future, bring it close enough to Earth to pose a problem.

These asteroids are among hard-to-find objects that will allow astronomers to better characterize the population of near-Earth objects. Therefore, their discovery is pretty exciting.

Minor planets and Trojan asteroids orbit at distances greater than Earth

According to astronomers, it was discovered that most minor planets in the solar system—objects in orbit around the Sun that are neither planets nor comets—have been discovered at orbital distances greater than that of Earth.

These include the asteroid belt between Mars and Jupiter, the Kuiper Belt out past Neptune wherein Pluto resides, and a bunch of other rocks, such as Greek and Trojan asteroids that share planetary orbits.

However, not much in the way of minor planets has been discovered closer to the Sun. This is probably for very good reason although it is vital to look towards a big, bright star, whose blinding light makes small, dim asteroids pretty undetectable. Astronomers are more likely to find objects when looking away from the Sun in a direction that faces the outer solar system.

In order to spot objects like asteroids in the inner solar system, astronomers need to wait until the twilight hours at dawn and dusk when the Sun’s glare mostly lies below Earth’s horizon, providing just enough light to illuminate inner objects that might be sweeping through space.

Atira asteroids previously discovered

A team of astronomers conducted a search in the inner solar system to investigate large patches of space closer to the Sun than Earth and Venus, and they consequently came up with fascinating discoveries.

Led by astronomer Scott S. Sheppard of the Carnegie Institution for Science, these discoveries include the 2021 PH27, an asteroid with the shortest orbit of any asteroid found yet at just 113 days. The 2021 LJ4 also circles the Sun entirely within Earth’s orbit. Both are known as Atira asteroids.

Sheppard said, “So far we have found two large near-Earth asteroids that are about one kilometer across, a size that we call planet killers.”

“There are likely only a few near-Earth asteroids with similar sizes left to find, and these large undiscovered asteroids likely have orbits that keep them interior to the orbits of Earth and Venus most of the time,” he explained. “Only about [twenty-five] asteroids with orbits completely within Earth’s orbit have been discovered to date because of the difficulty of observing near the glare of the Sun.”

Monster Apollo asteroid has elliptical paths

The third asteroid discovered, 2022 AP7, was classified under the Apollo asteroids, which are known to have elliptical paths that take them from a space closer to the Sun to beyond Earth’s orbit.

However, if these kinds of asteroids cross our orbit, it is feared they may venture close enough to our planet, hence risking a collision which earns them a classification of being “potentially hazardous.”

Over two thousand potentially hazardous asteroids, with the largest about seven kilometers in diameter, are known of today. Astronomers have credible information about these, implying it is possible to model their orbits and calculate if and when they are likely to come within hazardous range of Earth. Therefore, with enough notice, they might be able to do something about such an event and hopefully slam a spacecraft into their surface to divert their course.

Nevertheless, discovering new Atira asteroids is equally important because an understanding of the minor planet population of the solar system is primarily based on a census of space rocks in the farther reaches.

Therefore, having a better idea of what is in the inner solar system can tell us more about solar system dynamics and how asteroids are transported to various regions. We can also obtain more accurate models of the system’s evolution over time.

Furthermore, Sheppard goes on to say that “our DECam survey is one of the largest and most sensitive searches ever performed for objects within Earth’s orbit and near…Venus’s orbit.”

He added that “this is a unique chance to understand what types of objects are lurking in the inner solar system.”

Survey identified many larger asteroids

Although researchers were more focused on identifying smaller objects in the solar system, interestingly enough, the survey has uncovered a greater number of larger asteroids found to be at least a kilometer in diameter.

Smaller asteroids are perhaps less stable in the inner solar system or more susceptible to breaking apart in the intense thermal and gravitational environment closer to the Sun. This is a discovery that raises concern over smaller asteroids being harder to detect—hence making an excellent case for more sensitive surveys in the future.