Is Earth's "Quasi-Moon" Really a Piece of the Moon? What China's Tianwen-2 Is Finding
A small asteroid that loops alongside Earth was long thought to be a fragment knocked off the Moon. New observations are putting that idea under pressure, and a spacecraft is now sitting next to it.
What Kamo'oalewa is
Kamo'oalewa (also called 2016 HO3) is one of seven known Earth quasi-satellites. Its orbit around the Sun tracks Earth's, so from our viewpoint it seems to circle us like a slow second moon, though it is not bound to Earth by gravity. Pan-STARRS in Hawaii discovered it on April 27, 2016.
What Tianwen-2 has done
According to SpaceNews and Sci.News, China's Tianwen-2 launched on May 29, 2025 and closed to about 20 km from the asteroid on July 2, 2026, when it took its first image. China announced the arrival on July 6, 2026. The plan is to collect around 100 grams of material, leave in April 2027 and return a capsule to Earth in late November 2027, as summarised by OrbitalHub.
Why the "piece of the Moon" idea is wobbling
The lunar idea came from two clues: a 2021 spectrum that looked red like weathered lunar rock, and a 2024 paper pointing to the far-side Giordano Bruno crater as a possible source. OrbitalHub's roundup lists three recent challenges:
- A population model (Astronomy & Astrophysics) found main-belt asteroids far likelier to produce such an object than Giordano Bruno ejecta: about 1.23 versus 0.042 expected objects.
- A May 2026 Nature Communications paper says the spectrum fits LL chondrite meteorites once heavily weathered.
- New James Webb observations found a less red, much brighter surface, closer to some asteroid types than to lunar material.
After the first image, astronomer Mikael Granvik told SpaceNews the brightness it implies is not compatible with lunar material, so the rock "seems to be of asteroidal origin".
What is still unknown
None of this is final. The three studies do not agree on which kind of asteroid it is, and the Webb result is a preprint. Only returned samples can be compared properly with Moon rocks and meteorites.
Sources
- SpaceNews, "Tianwen-2 arrives at asteroid Kamo'oalewa, first image revealed", July 6, 2026: https://spacenews.com/tianwen-2-arrives-at-asteroid-kamooalewa-first-image-revealed/
- Sci.News, "China's Tianwen-2 Spacecraft Reaches Earth's Quasi-Moon": https://www.sci.news/space/tianwen-2-earths-quasi-moon-2016-ho3-14897.html
- OrbitalHub, "Tianwen-2's first look at Kamo'oalewa, and why its lunar origin is wobbling", October 3, 2026: https://orbitalhub.com/2026/10/03/tianwen-2s-first-look-at-kamo%CA%BBoalewa-and-why-its-lunar-origin-is-wobbling/
Facts checked: October 4, 2026. Study details come from OrbitalHub's summary; we did not read the papers.