- oceanus
- An ocean.
obliquity
- The angle between a body's equatorial plane and orbital plane.
occulation
- The blockage of light by the intervention of another object; a planet
can occult (block) the light from a distant star.
old
- A planetary surface that has been modified little since its formation
typically featuring large numbers of impact craters;
(compare to young).
Oort, Jan Hendrik 1900-1992
- Dutch astronomer. Oort made major contributions to knowledge of
the structure and rotation of our galaxy. More or less as a
sideline, Oort studied comets
as well. The result of this work was a theory, now widely
accepted, that the Sun is surrounded by a distant cloud of
cometary material, now called the Oort Cloud, bits of which
are occasionally hurled into the Solar System as comets.
orbit
- The path of an object that is moving around a second object or point.
ovoid
- Shaped like an egg.
