- Industry: Astronomy
- Number of terms: 6727
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Planetary Science Research Discoveries (PSRD) is an educational site sharing the latest research by NASA-sponsored scientists on meteorites, asteroids, planets, moons, and other materials in our Solar System. The website is supported by the Cosmochemistry Program of NASA's Science Mission ...
The time when the Sun is 12-18 degrees below the horizon. When the Sun moves from 19 to 18 degrees below the horizon, astronomers can begin to detect an increase in the brightness of the sky, although to the naked eye the sky still looks dark.
Industry:Astronomy
Mixture of gases that surround and are gravitationally attached to a planet.
Industry:Astronomy
Fluid magma that flows onto the surface of a planet or moon; erupted from a volcano or fissure. Also, the rock formed by solidification of this material.
Industry:Astronomy
An element with atomic number 8; symbol: O. It is actually the most common element in the crusts and mantles of the inner planets and rocky moons, making up all silicate minerals. Along with hydrogen, carbon, and nitrogen, oxygen is essential to life.
Industry:Astronomy
The random movement (spreading) of molecules from regions of highest concentrations to regions of lowest concentrations.
Industry:Astronomy
The spontaneous breaking apart, or decay, of unstable nuclei in isotopes. The unstable radioactive isotope is called the parent, and the products of the decay of the parent are called the daughter isotopes.
Industry:Astronomy
The amount of time required for half of the mass of a radioactive isotope to decay.
Industry:Astronomy
A stony-iron meteorite that is a mixture of isolated silicate crystals (usually olivine) surrounded by metal.
Industry:Astronomy
