- 産業: 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 fourth state of matter beyond solid, liquid, and gas. Plasma may be the most common state of matter in the universe. Our Sun is plasma. In space science, plasma is hot, ionized gas--a mixture of electrons (negative electric charge) and protons (positive electric charge). Plasma conducts electrical currents and responds to electromagnetic fields.
Industry:Astronomy
Streams of plasma--charged particles (mainly ionized hydrogen and some helium but actually a mixture of all electrons and protons in the Sun)-- ejected from the outer atmosphere (corona) of the Sun and moving outward all the time with velocities in the range 300-500 kilometers per second. For amazing images and information about the Sun and solar wind see the SOHO website for the Solar and Heliospheric Observatory, a project of international cooperation between ESA and NASA.
Industry:Astronomy
The ability or tendency of one substance to dissolve into another at a given temperature and pressure.
Industry:Astronomy
The scientific study of minerals. This is the field within geology that focuses on the chemistry, structure, properties, and classification of minerals.
Industry:Astronomy
Variable radio star having stable, very short (around one second) periods of pulsations. Electrons moving rapidly in a pulsar's magnetic field produce narrow beams of radiation which sweep around as the pulsar spins (analogous to sweeping search-light beams).
Industry:Astronomy
The part of Earth's crust, water, and atmosphere where living organisms can survive.
Industry:Astronomy
A point on the surface of a sphere that is located diametrically opposite another point. For example, on the Earth the antipode of Hawaii is Botswana. The term is used commonly in lunar geology to describe locations on the Moon in relation to impact basins. Researchers have hypothesized that accumulations of converged ejecta materials, production of impact shock stresses, anomalies in lunar crustal magnetic fields, and geochemical anomalies are associated with antipodes of basins.
Industry:Astronomy
Extremely high-energy subatomic particles that continuously bombard Earth from all directions. Most cosmic rays hit and break up atomic nuclei in Earth's upper atmosphere. Airless bodies are not protected and their surfaces (asteroids, for example) are exposed.
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
