21) What evidence is there that Neptune's moon Triton has been geologically active recently?

4) Science fiction movies often portray asteroid belts as crowded, dense regions that require spaceships to maneuver quickly to get through them. In this problem, we will calculate the fraction of volume in an asteroid belt that is actually occupied by asteroids. a) If there are 300,000 large asteroids between 2 and 3 AU from the Sun, and each asteroid is assumed to be spherical with a radius of 100 km, determine the total volume occupied by asteroids in this region. Recall that the volume of a sphere is given by the equation V = 4TR³ /3. b) Let's assume the region in which these asteroids orbit is an annulus with an inner radius of 2 AU, an outer radius of 3 AU, and a thickness of 2Ro. Determine the volume of this region. Recall that the area of a circle is given by the equation A = TR². Here are two conversions that you'll need: 1 AU = 1.496 × 108 km and 1 Ro = 6.955 × 105 km. c) What is the ratio of the volume occupied by asteroids to the volume of the asteroid belt (i.e., the…

Enceladus is a moon of Saturn. What unique feature does it possess? which is the correct answer?     Cryovolcanism, where water erupts instead of silicate rock     A dense system of rings     An atmosphere thicker than Earth's     Internal heating due to radioactivity     Has an orbit inside Saturn's rings

Question: The current and most scientifically accurate theory for the formation of the Moon is:  a.) The large impact theory.  b.) The capture theory.  c.) The fission theory.  d.) The twin formation theory.