Earth (Planet)
Planet that is the third in order from the sun. It is one of the four inner or terrestrial planets of the SOLAR SYSTEM.
Evolution, Planetary
Creation and development of bodies within solar systems, includes study of early planetary geology.
Exobiology
The interdisciplinary science that studies evolutionary biology, including the origin and evolution of the major elements required for life, their processing in the interstellar medium and in protostellar systems. This field also includes the study of chemical evolution and the subsequent interactions between evolving biota and planetary evolution as well as the field of biology that deals with the study of extraterrestrial life.
Astronomy
Stars, Celestial
Extraterrestrial Environment
The environment outside the earth or its atmosphere. The environment may refer to a closed cabin (such as a space shuttle or space station) or to space itself, the moon, or other planets.
Astronomical Phenomena
Aggregates of matter in outer space, such as stars, planets, comets, etc. and the properties and processes they undergo.
Minor Planets
Small solar system planetary bodies including asteroids. Most asteroids are found within the gap lying between the orbits of Mars and Jupiter.
Mercury (Planet)
The first planet in order from the sun. It has no known natural satellites. It is one of the four inner or terrestrial planets of the solar system.
Solar System
The group of celestial bodies, including the EARTH, orbiting around and gravitationally bound by the sun. It includes eight planets, one minor planet, and 34 natural satellites, more than 1,000 observed comets, and thousands of lesser bodies known as MINOR PLANETS (asteroids) and METEOROIDS. (From Academic American Encyclopedia, 1983)
Neptune
The eighth planet in order from the sun. It is one of the five outer planets of the solar system. Its two natural satellites are Nereid and Triton.
Atmosphere
Life
The state that distinguishes organisms from inorganic matter, manifested by growth, metabolism, reproduction, and adaptation. It includes the course of existence, the sum of experiences, the mode of existing, or the fact of being. Over the centuries inquiries into the nature of life have crossed the boundaries from philosophy to biology, forensic medicine, anthropology, etc., in creative as well as scientific literature. (Random House Unabridged Dictionary, 2d ed; Dr. James H. Cassedy, NLM History of Medicine Division)
Meteoroids
Mars
The fourth planet in order from the sun. Its two natural satellites are Deimos and Phobos. It is one of the four inner or terrestrial planets of the solar system.
Biogenesis
Uranus
The seventh planet in order from the sun. It is one of the five outer planets of the solar system. It has five known natural satellites.
Evolution, Chemical
Chemical and physical transformation of the biogenic elements from their nucleosynthesis in stars to their incorporation and subsequent modification in planetary bodies and terrestrial biochemistry. It includes the mechanism of incorporation of biogenic elements into complex molecules and molecular systems, leading up to the origin of life.
Geology
Tidal Waves
Water waves caused by the gravitational interactions between the EARTH; MOON; and SUN.
Moon
Pluto
The ninth planet in order from the sun. It is one of the five outer planets of the solar system. Its only natural satellite is Charon.
Spacecraft
Space Flight
Travel beyond the earth's atmosphere.
Jupiter
The fifth planet in order from the sun. It is one of the five outer planets of the solar system. Its sixteen natural satellites include Callisto, Europa, Ganymede, and Io.
Space Simulation
An environment simulating one or more parameters of the space environment, applied in testing space systems or components. Often, a closed chamber is used, capable of approximating the vacuum and normal environments of space. (From NASA Thesaurus, 1988) This also includes simulated EXTRAVEHICULAR ACTIVITY studies in atmosphere exposure chambers or water tanks.
Solar Activity
Metals, Alkaline Earth
Cosmic Dust
Cosmic Radiation
High-energy radiation or particles from extraterrestrial space that strike the earth, its atmosphere, or spacecraft and may create secondary radiation as a result of collisions with the atmosphere or spacecraft.