# Would a system consisting of Earth and Venus orbiting around a common center be stable in the long-term?

Earth and Venus and very close to each other in mass and would both orbit around a point in space positioned almost perfectly in between the two.

Assume that this system is 1 AU from the Sun and the distance between Earth and Venus is the same as the distance between the Earth and the Moon. Would this system be stable in the long-term?

Both planets would very likely be tidally locked to each other, but I'm not sure if that would have any impact on stability.

PSA: I only used Venus and Earth because they're very close to each other in mass. What I'm really curious about is if a double planet consisting of 2 components very similar in mass can be stable in the long-term.

• FWIW, using 384399 km for the semi-major axis, and grav params of Venus & Earth from Horizons, the orbital period of the Venus-Earth binary system (ignoring the Sun) is 1760541.5 seconds = 20.37664 days = 20 d, 09 h 02 m 21.5 s. The distances from the barycentre are 211790.3 km & 172608.7 km. Commented Dec 21, 2021 at 0:01