A(n) ________ (wandering star) is an astronomical object, circling around a star that is massive enough to be rounded by its own gravity. A(n) ______ is a giant luminous sphere(发光球体) held together by gravity. The nearest one to Earth is the Sun, which is the source of most of the energy. A(n) ______ is an icy small Solar System body with a tail sometimes. A(n) _______ is a small planet especially one of the inner Solar System.

Some heaven bodies in The Solar System

planet; asteroid; comet; star

planet

star

comet

asteroid