A lost Moon? Asteroid flying in similar orbit as Earth could be from Moon

 

Dubbed Kamo`oalewa, astronomers have concluded that this near-Earth asteroid could be a part of the Moon.

Moon has always fascinated humans, so much so that we landed on its surface way back in 1969 to find a desolate, cratered landmass that has survived millions of years of meteor and space bombardments. But it's not the only lunar fragment in space.

Moon was formed after a Mars-sized body collided with Earth and the debris formed into the most prominent feature in our night sky. A discovery now shows that a fragment of the lunar surface is out there orbiting the Sun, remaining relatively close to Earth.

Dubbed Kamo`oalewa, astronomers have concluded that this near-Earth asteroid could be a part of the Moon, but little was known about it due to its small size, making it faint and difficult to observe. Called quasi-satellites of the Earth, Kamooalewa is one of the five such objects discovered out there.

In a paper published in Nature Communications, a team of astronomers led by the University of Arizona said that the asteroid can only be observed from Earth for a few weeks every April due to its orbit. Astronomers used the Large Binocular Telescope on Mount Graham in southern Arizona to track the movement of the asteroid.

The asteroid first detected in 2016 is named after the Hawaiian creation chant alludes to an offspring that travels on its own. Astronomers said that the asteroid is roughly the size of a Ferris wheel between 150 and 190 feet in diameter and gets as close as about 9 million miles from Earth.

HOW DO WE KNOW IT'S PART OF THE MOON?

Ben Sharkey, a science graduate student with the University found that Kamo`oalewa's pattern of reflected light, called a spectrum, matches lunar rocks from Nasa's Apollo missions, suggesting it originated from the moon. "I looked through every near-Earth asteroid spectrum we had access to, and nothing matched," said Sharkey, the paper's lead author.

Researchers aren't yet sure how the asteroid may have broken loose from the Moon. That's partly because there are no other known asteroids with lunar origins. The paper comes on the back of three years of extensive research as Sharkey and his adviser Vishnu Reddy associate professor of lunar and planetary sciences worked on analysing the possible origins of the fragment.

"We doubted ourselves to death. This spring, we got much-needed follow-up observations and went, 'Wow it is real'. It's easier to explain with the moon than other ideas," Sharkey said.

A SIMILAR ORBIT TO EARTH

A major clue indicating that Kamo`oalewa's has a lunar origin is its orbit, which is similar to the Earth's, but with the slightest tilt. 

"It is very unlikely that a garden-variety near-Earth asteroid would spontaneously move into a quasi-satellite orbit like Kamo`oalewa's. It will not remain in this particular orbit for very long, only about 300 years in the future, and we estimate that it arrived in this orbit about 500 years ago," study co-author Renu Malhotra, a planetary sciences professor said in a statement.

Researchers said that Kamo`oalewa is about four million times fainter than the faintest star the human eye can see in a dark sky.