Star Trillian-2009 was initially observed by astronomers to spin with a period of 25 days, and was computed to have a rotational inertia of 23.81 IARIU (International Astronomical Rotational Inertia Units). It then undergoes a change, and the new rotational inertia is calculated to be a third of the original value.

Star Trillian-2009 was initially observed by astronomers to spin with a period of 25 days, and was computed to have a rotational inertia of 23.81 IARIU (International Astronomical Rotational Inertia Units). It then undergoes a change, and the new rotational inertia is calculated to be a third of the original value.