Hi: ) i don’t understand why it causes the rocks to melt at low temperature. one of the factors causing rocks to melt is increased temperature. however, why does this factor cause rocks to melt at low temperature? i’m very confused, pls ! you :

Rocks melt at a lower temperature in the presence of volatiles such as water and carbon dioxide. ... As the cold slab sinks, water is forced out and percolates upward into the overlaying hot, dry mantle rock. This sudden addition of water lowers the melting point of that mantle rock, and it begins to melt.

There’s no picture or character?

Why the planet stays in orbit is because of inertia (object stays in motion until a force changes it’s motion) also the atmosphere and gravity!