- target rocks
- The surface rocks that an asteroid or comet impactor smashes
into in a meteorite impact event.
tectonic
- The deformation forces acting on a planet's crust.
tektites
- Natural, silica-rich, homogeneous glasses produced by complete
melting, and dispersed as droplets during terrestrial impact events.
Tektites range in color from black or dark brown to gray or green and most
are spherical in shape. They have been found in four regional deposits
or strewn fields on the Earth's surface: North America,
Czechoslovakia, Ivory Coast and Australasia.
Terrestrial Planets
- Included in this group are the planets Mercury, Venus, Earth, and Mars. They are classified as terrestrial planets because of there compact, rocky, Earth-like appearence.
terminator
The dividing line between the illuminated and the unilluminated
part of the moon's or a planet's disk.
tessera
A tile; polygonal ground.
tholus
A small domical mountain or hill.
tidal forces
The gravitational pull on planetary objects from nearby planets and
moons. When the tidal forces of a planet and several moons are focused
on certain moons, particularly if the orbits of the various objects bring
them into alignment on a repeated basis, the tidal forces can generate a
tremendous amount of energy within the moon. The intense volcanic
acivity of Io is the result of the interaction
of such tidal forces.
tidal heating
The frictional heating of a satellite's interior due to flexure
caused by the gravitational pull of its parent planet and possibly
neighboring satellites.
Tombaugh, Clyde 1906-
American astronomer. Tombaugh discovered Pluto.
trailing hemisphere
The hemisphere that faces backwards, away from the direction of
motion of a satellite that keeps the same face toward the planet.
Trojan satellites
Satellites which orbit at the Lagrangian points, 60° ahead
of and 60° behind another satellite. For example,
Telesto and Calypso
are trojans of Saturn's satellite
Tethys.
troposphere
The lower regions of a planetary atmosphere where
convection keeps the gas mixed and maintains a
steady increase of temperature with depth. Most clouds are in the
troposphere.
tuff
The general term for consolidated pyroclastic debris.
