Space exploration began with the launch of Sputnik and Astrophysics was born as the application of physics to the phenomena observed by Astronomy, which etymologically means laws of the stars.
There are 2759 entries in this glossary.| Term | Definition |
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| N Galaxy |
An active galaxy with a compact and extremely bright nucleus, sometimes associated with a radio source.
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| N Star |
An obsolete stellar classification now incorporated into the group of carbon stars. The former N-type stars fall into classes C6 to C9.
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| N-Body Problem |
A general term for calculations involving the gravitational interaction of an arbitrary number n of masses. The motion of two bodies is easily analysed and solutions exist for certain cases of three-body interaction. For VALUES (of n greater than 2, there are no general solutions and particular cases necessitate vast amounts of computation. Examples in astronomy requiring the solution of n-body problems are the motion of a space probe in the solar system, and the orbits of stars within a cluster.
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| Nadir |
The point on the celestial sphere diametrically opposite the zenith.
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| Nagler Eyepiece |
A specialist telescope eyepiece with an exceptionally wide 80° field of view.
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| Naiad |
A satellite of Neptune 1989 N6 discovered during the flyby of Voyager 2 in August 1989.
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| Naked Singularity |
A singularity without an event horizon. According to the cosmic censorship hypothesis, this should not be possible. However, if the universe began as a singularity, the Big Bang was a naked singularity.
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| Naked-Eye Star |
A star visible in principle without the aid of a telescope. In principle, stars down to about sixth magnitude are visible to the naked eye under ideal conditions, but this is rarely achieved in practice except on moonless nights under transparent skies remote from artificial illumination.
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| Nakhlite |
A rare type of achondritic meteorite made of calcic pyroxene and olivine. Together with shergottites and chassignites, nakhlites belong to the class of SNC meteorites, believed to have originated on the surface of Mars.
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| Nançay |
The location in France of the radio astronomy station of the Observatoire de Paris.
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| Nanometre Symbol Nm |
One thousand-millionth 10 to the power of -9 of a metre.
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| Nanosecond |
One thousand-millionth 10 to the power of -9 of a second.
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| Narrabri |
Culgoora.
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| Narrow-Band Photometry |
The measurement of the magnitudes of stars in a set of narrow wavelength bands, typically less than 30 nanometres wide. The most commonly used narrow-band system is uvby photometry. The wavebands are isolated by means of standard filters. The narrow-band magnitudes can be used to determine basic physical properties of stars more simply and quickly than through spectroscopy, and are also useful for statistical studies on groups of stars.
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| Nasa |
Abbreviation for National Aeronautics and Space Administration.
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