+
NASA Homepage
+
NASA en Español
+
Contact NASA
SSE Home
> Dictionary
Dictionary Lookup
Can't find it? Don't understand it?
Ask us.
Find entries
starting with
containing
tail
In the case of a comet, the tail is a long linke of gas and dust that flow away from the nucleus and coma of the comet.
tectonic
Deformation forces acting on a planet's crust.
tectonism
The processes of faulting, folding or other deformation of the lithosphere of a planetary body, often the result of large-scale internal movements below the lithosphere.
terminator
The dividing line between the illuminated and the unilluminated part of the moon's or a planet's disk. The line of sunrise or sunset on a planet or its satellite. At dawn and dusk when the sun is lowest in the sky (low sun), topographic features cast their longest shadows. This reveals information about the size and shape of the objects casting the shadows. Therefore, features near the terminator are imaged in order to obtain morphologic information.
terra
An extensive land mass.
terrain
The surface features of an area of land.
terrestrial planets
The inner solar system planets: Mercury, Venus, Earth, Mars, composed of rocky materials and iron, with a density between 4.0 and 5.5 grams per cubic centimeter.
tessera
Tile; terrain formed of polygonal pattern
texture
The general appearance or character of a rock. (e.g. the size, shape, and arrangement of its constituent elements)
tholus
small domical mountain or hill.
tidal heating
Frictional heating of a satellite's interior due to flexure caused by the gravitational pull of its parent planet and possibly neighboring satellites.
topography
The general configuration of a land surface.
torus
A shape that resembles a doughnut or the inner-tube of a tire.
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
An object orbiting in the Lagrange points of another (larger) object. This name derives from a generalization of the names of some of the largest asteroids in Jupiter's Lagrange points: 588 Achilles, 624 Hektor, and 911 Agamemnon. Saturn's satellites Helene, Calypso and Telesto are also sometimes called Trojans.
troposphere
The layer of the atmosphere from the surface to where the temperature stops decreasing with height.
Explore more of NASA on the Web:
NASA Site Network
Ciencia@NASA
Earth Observatory
Great Images in NASA
Human Space Flight Web
Liftoff to Learning
Mars Exploration
NASA Education Program
NASA History
NASA Image Exchange
NASA Kids
NASA Science Update Newsletter
Planetary Photojournal
Science@NASA
NASA Technology
NASA Enterprises and Field Centers
Aeronautics Research
Earth Science
Exploration Systems
Office of Space Operations
Space Science
NASA Headquarters
Ames Research Center
Dryden Flight Research Center
Glenn Flight Research Center
Goddard Space Flight Center
Jet Propulsion Laboratory
Johnson Space Center
Kennedy Space Center
Langley Research Center
Marshall Space Flight Center
Stennis Space Center
+
Awards & Recognition
+
Send to a Friend
+
The Vision for Space Exploration
+
NASA Solar System Exploration Roadmap
+
Privacy/Copyright/Image Use Policy
NASA Official: Marilyn Lindstrom
Outreach Manager: Alice Wessen
Editors: Phil Davis and Kirk Munsell
Science Writer: Samantha Harvey
Webmaster: David Martin
Last Updated: 30 Dec 2008
+
Contact Us