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Old 10-18-2017, 03:38 PM   #10
a humble lich
Join Date: Jun 2017
Default Re: [Space] Triple Full Moons

Putting some numbers in, the moons are so close, I think they could be visible. You're right that they are inside the Roche limit, although for the farther moons they are close to the limit, so they are probably small captured asteroids. If the closest one is the size of Phobos (i.e. about 20 km) and Lerrom is about earth-sized, then Moon A will subtend an arc of about 0.18 degrees. For comparison, our moon subtends 0.5 degrees, so Moon A would be a little smaller than half the size of our moon.

The Roche limit also depends on the density of the satellite, so if these moons are captured asteroids with a high iron content, they could be bigger.

I'm wondering what tides are like. If the moons are tiny there won't be much tides, I calculate for the case of Phobos being Moon A the tidal acceleration from Moon A would be about 1% of what Earth gets from our moon. However, if the moons are larger and denser, that would go up.
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