As a radioactive substance gradually decays, the abundance of daughter ____ gradually increases.​

​Which best describes the surface of Callisto?

Martian volcanoes are _______________ volcanoes with gradual slopes.

Almost all geological features on Venus have _______________ names.​

    What is the current dominant geological process on Mars?​

All the planets in the Solar System revolve in a clockwise motion.

​Which space mission orbited Saturn and dropped a probe into Saturn’s atmosphere?

​ Kuiper belt objects appear to be ancient planetesimals that formed in the outer Solar System but were never incorporated into a planet.

​Scientists believe Saturn’s moon Phoebe originated from a ____.

​The Babcock model of the solar magnetic cycle explains the sunspot cycle as primarily a consequence of the Sun’s ____.