- 行业: 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 ...
An element with atomic number 16; symbol: S. Sulfur is common on the surface of Jupiter's moon Io.
Industry:Astronomy
Technique to determine the age of a rock by measuring the last time the rock being dated was either melted or disturbed sufficiently to rehomogenize its naturally-occurring radioactive elements. This is accomplished because of the decay of long-lived radioactive isotopes. Some of the parent-daughter isotopes used as chronometers to determine the age of extraterrestrial rocks are: aluminum-magnesium, uranium-lead, thorium-lead, rubidium-strontium, potassium-argon, samarium-neodymium, and lutetium-hafnium.
Industry:Astronomy
Celestial coordinate which is equivalent to the longitude of an object on Earth. The starting point for longitude on Earth is at Greenwich England, whereas in the celestial coordinate system it is at a point in the sky called the vernal equinox. The two great circles defined by the celestial equator and the ecliptic, which is defined as the plane of the Solar System, cross each other at 2 points: at the vernal equinox (first day of spring) and the autumnal equinox (first day of autumn). The vernal equinox is the starting point for the RA coordinate system.
Industry:Astronomy
The Sun and all the objects (planets, moons, asteroids, and comets) that orbit the Sun.
Industry:Astronomy
A temperature scale with the freezing point of water assigned the value 32 °F and the boiling point of water 212 °F at standard pressure. To convert Fahrenheit to Celsius: Deduct 32, then multiply by 5, then divide by 9.
Industry:Astronomy
The configuration (shapes, positions, arrangements) and relief (elevations, slopes) of the land surface.
Industry:Astronomy
The percentage of the total volume of rock or soil that consists of open spaces. (The space between particles is called pore space. )
Industry:Astronomy
Celestial coordinate which is equivalent to the latitude of an object on Earth. This is an angular measure of how far above the celestial equator an object lies.
Industry:Astronomy
A small body (a "dirty iceball", typically 1 km across, with dust and plasma tails) that circles the Sun with a highly elliptical orbit.
Industry:Astronomy
