If it's a constant it can't be changed. So gravitational acceleration must be a variable, because it varies from celestial body to celestial body. It's huge on Uranus, Jupiter and Saturn and it's small on the moon, because the Moon itself is small ... well you know how gravity works :)

So it's variable Gravitational_acceleration. Then you define another variable called Astronomical_object(planets, moons, stars). So now you can do this: If Astronomical_object === "Earth" display ... else if Astronomical_object==="Moon" display ...

Anyway the only problem to your code is making Gravitational_acceleration a constant. If you want to simply post both with no input from the user, then what you did is fine except make it a variable.

You said GRAVITY is a constant, so you can't change it.

Pseudocode usually don't have precise declarations, although there are no real rules for pseudocode.

Either the declaration is wrong, or the second assignment is wrong.