S&T this month has a news blurb about the "moon race" ... Teams competing to find more moons around Jupiter and Saturn. Jupiter is up to 60, and Saturn up to 31.
The article says the moons being found are of the order of about 2km or larger.
That seems awfully small, but then, I thought, if we were talking about earth moons, I would have no problem with it if it were naked-eye visible from the ground. But I don't know enough about mechanics to know how far out a 2km chunk of moon stuff would have to be to stay in orbit around the earth.
And at that distance, x, what would a 2km large 2nd moon look like to us on the ground if we had one? Invisible? Like the ISS but further out? At what size then is it "debris" and not a moon? Does it have to be spherical (mostly)?
You see what I'm getting at: intuition tells me naked eye visible ( from your host planet ) natural satelite.
but science is something like equal parts:
sherical (though not always a disqualifier).
regular orbit (of course)
diameter (but at 2km is there really a cut off? when?)
who knows.
T.
The article says the moons being found are of the order of about 2km or larger.
That seems awfully small, but then, I thought, if we were talking about earth moons, I would have no problem with it if it were naked-eye visible from the ground. But I don't know enough about mechanics to know how far out a 2km chunk of moon stuff would have to be to stay in orbit around the earth.
And at that distance, x, what would a 2km large 2nd moon look like to us on the ground if we had one? Invisible? Like the ISS but further out? At what size then is it "debris" and not a moon? Does it have to be spherical (mostly)?
You see what I'm getting at: intuition tells me naked eye visible ( from your host planet ) natural satelite.
but science is something like equal parts:
sherical (though not always a disqualifier).
regular orbit (of course)
diameter (but at 2km is there really a cut off? when?)
who knows.
T.
