- 産業: Astronomy
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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 ...
A gas molecule composed of one part nitrogen and three parts hydrogen; NH<sub>3</sub>.
Industry:Astronomy
A table of positions in right ascension (celestial coordinate corresponding to longitude on Earth) and declination (celestial coordinate corresponding to latitude on Earth), as a function of time for a moving celestial object.
Industry:Astronomy
The official scale (created by Professor Richard P. Binzel and formalized in Torino, Italy in 1999) for categorizing the Earth impact hazard for asteroids and comets. Values range from 0 (no chance of collision with Earth) to 10 (collision with global climatic disasters). (Torino Scale)
Industry:Astronomy
Group of asteroids with similar orbital elements (distance from the Sun, inclination of the orbital plane to the Earth's orbital plane, and eccentricity of the orbit) thought to be remnants of one larger asteroid parent.
Industry:Astronomy
Crack extending far into a planet or moon through which magma travels to and erupts onto the surface.
Industry:Astronomy
The relationship of a distance on a map or model to the true distance in space; written as a ratio, such as 1:24,000.
Industry:Astronomy
Unit of measure that is one-billionth of a meter. A nanometer-sized particle is smaller than a living cell and can only be seen with the most powerful microscopes.
Industry:Astronomy
A constant value: 299,792,458 meters per second (186,282 miles per second).
Industry:Astronomy
Apparent motion of a nearby object as projected against more distant background objects due to the motion of the observer.
Industry:Astronomy
