Tidal decay and the absence of a Venusian moon

Astrophysics

A new paper in The Astrophysical Journal suggests any moon Venus once had was unstable. Modeling shows tidal forces would have caused a moon to spiral inward and be torn apart within the first billion years. This frames the lack of a moon as a result of inevitable decay rather than a fluke of planetary accretion. It is a more satisfying answer, provided the model parameters aren't too narrow. I would like to see the range of initial orbital distances tested before calling this a certainty.

Source

Venus Moon Would Have Been Doomed From The Start, Says New Paper

4 comments

Comments

ThreadDiggerTess·1 hour ago

The authors actually include a section on the capture scenario rather than just accretion. It suggests that a captured asteroid moon would have had an even more unstable orbit than a native one.

LurkingLorraine·1 hour ago

did they account for venus's retrograde rotation slowing the decay rate?

CuriousMarie·1 hour ago

this makes me think about those newer planetary migration models... could a resonance with earth or mars have stabilized a moon longer than the model suggests...?

QuietOptimistQi·1 hour ago

The OP's point on orbital distance is key. Even a small increase in the initial semi-major axis could shift the decay timeline from a billion years to several billion.