This week’s image comes from a Chinese probe called Tianwen-2. It shows the spinning asteroid 2016 HO3, or Kamo‘oalewa, which is labeled by some of a “quasi-moon” of Earth until it decides to move on. Unlike the actual Moon, this asteroid is simply joining the Earth as it circles the Sun. The asteroid is about the size of a school bus.
The Chinese probe, launched from China in May 2025, is believed to have started its orbit of asteroid Kamo‘oalewa on June 6th of this year. It is now believed to be a rubble-pile asteroid, meaning it is basically loose material rather than a solid object. Even so, the Chinese probe may try to grab a sample to be returned to Earth in November 2027.
The source of the asteroid is still being debated, with some believing it is a piece of the Moon dislodged by an incoming asteroid while others believe it comes from the main asteroid belt.
In a paper released last year, scientists were leaning towards its origin being the main asteroid belt, noting:
Quantitative estimates show that population models of [Near Earth Asteroids] based on the migration of objects from the main belt are capable of accounting for Kamo‘oalewa-like objects. This relative contribution supports the hypothesis that (469219) Kamo‘oalewa originated from the main belt, which will be further investigated by future observations and in situ exploration of the Tianwen-2 spacecraft.
How long will it remain Earth’s partner? Back in 2021, Renu Malhotra, a UArizona planetary sciences professor, stated:
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.
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