That's if you use what Asimov calls "tug of war" as your definition: https://en.wikipedia.org/wiki/Tug_of_war_(astronomy) https://en.wikipedia.org/wiki/Tug_of_w

That's if you use what Asimov calls "tug of war" as your definition: https://en.wikipedia.org/wiki/Tug_of_war_(astronomy) https://en.wikipedia.org/wiki/Tug_of_war_(astronomy) . I believe astronomers use the Hill sphere to define that bit of technicality. Quoting https://en.wikipedia.org/wiki/Hill_sphere https://en.wikipedia.org/wiki/Hill_sphere : > In the Earth example, the Earth (5.97E24 kg) orbits the Sun (1.99E30 kg) at a distance of 149.6 million km. The Hill sphere for Earth thus extends out to about 1.5 million km (0.01 AU). The Moon's orbit, at a distance of 0.384 million km from Earth, is comfortably within the gravitational sphere of influence ... All stable satellites of the Earth (those within the Earth's Hill sphere) must have an orbital period shorter than seven months. This asteroid is outside of Earth's Hill sphere so is in orbit around the Sun.