Earth's Second Moon Kamo'oalewa: Facts and Origins

The Wobbling Satellite Called Kamoʻoalewa

Earth has a second moon. Kamoʻoalewa is about the size of a football field, it’s been orbiting us for a century, and 2027 will be the year we find out if it’s a chunk of our first moon. Okay, formally named Kamoʻoalewa, it's a true wobbler. The ratio of its orbit is 1:1 with Earth (meaning it completes a lap for every lap Earth takes around the Sun), and yet it loops, winding around us in a slower, more unpredictable dance. Some call it a quasicompanion or a quasi-satellite. Its roots could be traced from the young crater Giordano Bruno on the far side of the Moon. It might be a planetesimal, but there could be another explanation. Kamoʻoalewa only reflects light as Moon rock. A probe from China’s Tianwen-2 mission, launched in 2025, is anticipated to return with samples in 2027. The probe's work includes collecting these samples from Kamoʻoalewa. Kamoʻoalewa’s wobbly, distant orbit presents a challenge, so it’s not a straightforward task.

Spotting Kamoʻoalewa: A Century of Discovery

Speaking from the public interest, Kamoʻoalewa's discovery in 2016 fell to the Pan-STARRS1 survey in Hawaii. It was hard to spot. It took years of scanning the skies to detect it. Recalling the fascinating discovery, few noticed it before. Once spotted, scientists were curious to learn about its origins. The Pan-STARRS1 survey was crucial for monitoring these occultations. Further research found that it had been orbiting with Earth for a long time, so it's a true companion. Its existence seems crucial in the history of space exploration. Many science enthusiasts are closely following this story. In 2027, if it's a piece of the Moon, Tianwen-2 will help us learn more about the Moon’s history around Earth.

The Truth About Kamoʻoalewa

Mysteries of the second moon

Kamoʻoalewa measurement, made in 2021, presents another mystery. Its spectral data were not consistent with an asteroid's, but a lunar rock's. The connection to the Giordano Bruno impact crater on the Moon’s far side strengthens the idea that Kamoʻoalewa was blasted off the lunar surface.

How Kamoʻoalewa Moves

An artist’s rendition of Kamoʻoalewa’s path around Earth orbits similarly to that of an asteroid. It moves into space, resembling a typical asteroid’s path rather than the moon's. Gravity pulls it back into the Earth-Moon system's gravitational dance. It won't break away from Earth anytime soon, although its orbit appears to change as it travels, the Moon’s gravity affects it. This dance in Earth’s orbit seems stable. It’s stable for a hundred years—and counting.

How Human Artifacts Could Do More

The Tianwen-2’s mission to Kamoʻoalewa in 2025 and 2027 will give us new information about our celestial bodies. Kamoʻoalewa relates to Earth and Moon. The probe will offer us an opportunity to explore origins of celestial bodies while studying the composition of such bodies. The information from the probe could also add to Earth's history.

Catalyzing the Space Exploration

Kamoʻoalewa's discovery surpasses a simple exciting story. It provides lessons in astrophysics. The probe that follows up on this story will further our space exploration efforts. We’ll learn from its orbit, movement, and composition. This story has a potential to add more insight and drive us to wonder about the wonders of our universe and the beginning of life. We might find new ways to look at space. An enormous reservoir of resources could fuel rocket propulsion. A cosmic body like the moon could make travel through celestial bodies more possible.

What to Watch

Full episodes on YouTube from @DeepPlanetTV.