- Отрасли: 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 ...
Astronomical brightness measured on a logarithmic scale, based on the ancient practice of noting that the brightest stars in the sky were of "first importance" or "first magnitude", the next brightest being "second magnitude" etc. The human eye is a logarithmic detector, and in 1854 Pogson formalized this scale and defined a difference of 5 magnitudes to be exactly a factor of 100 in brightness. The scale is calibrated to the bright star Vega which is defined to have a magnitude of 0. For reference, the faintest naked-eye magnitude visible from a dark site is +6. Comet C/1996 B2 Hyakutake reached magnitude 0 in late March 1996.
Industry:Astronomy
The central region of a planet or moon frequently made of denser materials than the surrounding regions (mantle and crust). Earth and the Moon are thought to have cores of iron and nickel.
Industry:Astronomy
Groups of thousands to millions of old stars held together in orbits about their own center of mass and arranged in almost symmetrical (spherical) clusters.
Industry:Astronomy
A hole or depression. Most are roughly circular or oval in outline. On Earth most natural craters are of volcanic origin. On the Moon most are of impact origin.
Industry:Astronomy
Iron meteorites are made, almost completely, of iron and nickel metal. They are chemically distinguished and grouped according to the abundances of the trace elements such as gallium and germanium, as well as nickel. Initially, irons were classified into four groups and were given Roman numerals I, II, III, and IV. Today twelve groups are recognized and designated further by letters A through F according to concentrations of siderophile ("iron-loving") trace elements. Iron meteorites that do not fit into the groups are called ungrouped. The two iron-nickel alloys in iron meteorites are called kamacite (low-nickel content, usually up to 7. 5 wt% nickel) and taenite (high-nickel content, ~20 to 50 wt% nickel). These alloys are rare in terrestrial rocks. (See also Widmanstätten Pattern. )
Industry:Astronomy
U. missione di S. Discovery-classe luna lanciato il 6 gennaio 1998. Suoi strumenti sono stati progettati per fornire mappe globali e insiemi di dati di composizione della luna e magnetici e campi di gravità da un'orbita polare bassa. La missione durò 18 mesi e si concluse il 31 luglio 1999 con un atterraggio controllato in un cratere presso il polo sud lunare.
Industry:Astronomy
An element that concentrates in iron or that forms alloys easily with iron. Siderophile means "iron loving. "
Industry:Astronomy
Una tecnica di misura di precisione utilizzata per analizzare quantitativamente gli elementi e isotopi di materiali su scala microscopica (con una risoluzione spaziale tipica di 1 micrometro). Uno strumento di SIMS è anche chiamato una microsonda ionica.
Industry:Astronomy
Uno strumento svolta a Giove la sonda planetaria di Galileo, di imaging nelle regioni dello spettro di energia che gli esseri umani non possono vedere. NIMS sito presso il Jet Propulsion Laboratory.
Industry:Astronomy
