IIRC, the IAU’s definition of planet – infamously applied so that Pluto fell off the list of Solar System planets – requires that a candidate planet be large enough that its own gravity is strong enough to force it into a rough sphere, whatever it might be made of.
So a disc-shaped planet could not ever meet this criteria, because if it were made of something strong enough to remain a disk, then it’s too small to be a planet. And if it did exceed the critical size for gravity to make a sphere, then it wouldn’t be disc shaped anymore.
But setting that definitional quibble aside, we will focus on sizes and materials that allow a disk shape object to exist and be large enough for humans (or Mario) to visit. So no Wensleydale cheese. If we say that this object is mostly uniform in its mass distribution, then it would have to be the case that for any disc shape (including cylindrical), different points along the surface will be farther or closer to the center of gravity. Thus, inhabitants would experience gravity differently depending on where they are.
Note that we haven’t even considered whether the disc is rotating. If it is, then there’s a chance that the centrifugal acceleration at some points will completely negate the gravitational acceleration. At such points, one could hop up and off the surface, linger for a bit, and then get pulled back down once the disc has rotated to a position where there’s a net force upon you again. Or if the centrifugal acceleration is too strong, it might repel visitors on the surface altogether.
Alternatively, there would be a danger of playing on a trampoline that accidentally crosses into a net-zero gravity region. Here, a double bounce could send someone very high up, only to then plummet back down to their death when re-entering a downward gravity zone.
I have almost no citations for the above, but I thank you for posing an interesting question.
IIRC, the IAU’s definition of planet – infamously applied so that Pluto fell off the list of Solar System planets – requires that a candidate planet be large enough that its own gravity is strong enough to force it into a rough sphere, whatever it might be made of.
So a disc-shaped planet could not ever meet this criteria, because if it were made of something strong enough to remain a disk, then it’s too small to be a planet. And if it did exceed the critical size for gravity to make a sphere, then it wouldn’t be disc shaped anymore.
But setting that definitional quibble aside, we will focus on sizes and materials that allow a disk shape object to exist and be large enough for humans (or Mario) to visit. So no Wensleydale cheese. If we say that this object is mostly uniform in its mass distribution, then it would have to be the case that for any disc shape (including cylindrical), different points along the surface will be farther or closer to the center of gravity. Thus, inhabitants would experience gravity differently depending on where they are.
Note that we haven’t even considered whether the disc is rotating. If it is, then there’s a chance that the centrifugal acceleration at some points will completely negate the gravitational acceleration. At such points, one could hop up and off the surface, linger for a bit, and then get pulled back down once the disc has rotated to a position where there’s a net force upon you again. Or if the centrifugal acceleration is too strong, it might repel visitors on the surface altogether.
Alternatively, there would be a danger of playing on a trampoline that accidentally crosses into a net-zero gravity region. Here, a double bounce could send someone very high up, only to then plummet back down to their death when re-entering a downward gravity zone.
I have almost no citations for the above, but I thank you for posing an interesting question.
A disc-shaped body may not be a planet, technically. But it would still be a workd. A discworld, if you will. Ook.
Humans that successfully visit would be honored as a Discman.
Not the double bounce?!