| Explorations: Stars, Galaxies, and Planets Thomas Arny,
University of Massachusetts
Gravity and Motion
OverviewGravity gives the Universe its structure. It is a universal force that acts
on all the objects in the Universe so that every particle is drawn toward every
other particle by its pull. Gravity holds together astronomical bodies of all
sizes, from the Earth to the Universe itself. But the role of gravity extends
beyond giving structure to astronomical bodies. Gravity also controls their
motions, holding the Earth in orbit around the Sun, the Sun in orbit around
the Milky Way, and the Milky Way within the Local Group. Thus, gravity and motion
are tightly connected in the Universe. This connection is the theme of this
chapter. |
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