China's Tianwen-2 Spacecraft Captures First Close Images of Earth's 'Second Moon' Asteroid

Earth officially has one moon, but it also has a small, unusual companion asteroid named 2016 HO3, or Kamoʻoalewa, which orbits the Sun in a way that makes it appear to accompany Earth in a slow, continuous dance. Discovered about a decade ago by an asteroid survey in Hawaii, this object has only been observed from afar until now. Recently, China's Tianwen-2 spacecraft, launched in May 2025 on a mission to return samples from an asteroid, approached Kamoʻoalewa to within 20 kilometers after a 400-day journey covering nearly one billion kilometers. It captured the first close-up images of the asteroid, revealing a small space rock estimated to be between 40 and 100 meters in diameter.

Kamoʻoalewa is not a true moon because it does not orbit Earth directly; instead, it orbits the Sun in a path very similar to Earth's, causing it to stay near our planet for extended periods. Scientists classify such objects as "quasi-satellites." NASA calculations show that Kamoʻoalewa has been in this quasi-orbit for nearly a century and is expected to remain for several hundred more years. The gravitational interaction with Earth causes it to move closer and farther in a complex orbital dance.

The close-up images from Tianwen-2 mark a significant milestone, as previously Kamoʻoalewa was only a tiny point in telescope observations. These new visuals allow researchers to study its shape, surface structure, and composition in detail, determining whether it is a solid rock or a loose collection of fragments. The spacecraft plans to collect samples from the asteroid and return them to Earth, which could provide crucial insights into its origin.

One intriguing hypothesis is that Kamoʻoalewa might be a fragment of the Moon itself, ejected into space by an ancient impact. Previous studies found similarities between the asteroid's surface minerals and lunar rocks brought back by NASA's Apollo missions. Confirmation from returned samples would be groundbreaking, suggesting this small body is a remnant of the Moon now orbiting near Earth.

After completing its work at Kamoʻoalewa, Tianwen-2 will release a capsule with the collected samples during a flyby of Earth and then continue to another deep-space target. For scientists, this mission and the new images provide an exciting opportunity to better understand this rare "second moon" and its relationship with our planet.