Iam struggling with some questions: 1) i need two objects or worlds that will still be geologically active when in 4byrs the earth will have entered its big chill.
2) how most meteorites get from the asteroid belt to the earth?
3) why earth's moon cannot retain an atmosphere and saturn's moon and titan can?
4) why cannot determine the absolute ages of the surfaces of jupiter's moons, calisto and genymede