47 lines
2.2 KiB
HTML
47 lines
2.2 KiB
HTML
<html >
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<title >Netpune</title>
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</head>
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<body >
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<mbp:pagebreak>
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<tei-ms:entry>
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<tei-ms:orth><h1 align="center" >Neptune</h1></tei-ms:orth>
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</tei-ms:entry>
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<br />
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<div align="center" title="Neptune is the fourth largest planet in our Solar-system."><img src="neptune.jpg" /></div>
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<p ><b class="first" >N</b>eptune, fourth largest of the planets in the solar
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system, and eighth major planet in order of increasing distance from the sun.
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The mean distance of Neptune from the sun is 4.5 billion km, and its mean linear
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diameter is approximately 49,400 km, or about 3.8 times that of the earth.</p>
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<p >Its volume is about 72 times, its mass 17 times, and its mean density 0.31
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that of the <a href="earth.htm">earth</a>. The period of rotation is about 16 hr, and the period of
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revolution about the sun is 164.79 earth years. The average stellar magnitude of
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the planet is 7.8, and it is therefore never visible to the naked eye, but it
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can be observed in a small telescope as a small, round, greenish-blue disk
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without definite surface markings.</p>
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<p >The temperature of the surface of Neptune is about -218 degrees C , much like
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<a href="uranus.htm">Uranus</a>, which is more than 1 billion miles closer to the sun. Scientists assume,
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therefore, that Neptune must have some internal heat source. The atmosphere
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consists mostly of hydrogen and helium, but the presence of up to three percent
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methane gives the planet its striking blue color.</p>
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<p >Eight known satellites orbit Neptune, two of which are observable from earth.
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The largest and brightest is Triton, discovered in 1846, the same year Neptune
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was first observed. Triton, with a diameter of 2705 km, is only slightly smaller
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than earth's moon. It has a retrograde orbit-that is, opposite its primary's
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direction of rotation-unlike any other major satellite in the solar system.
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Despite its extreme coldness, Triton has a nitrogen atmosphere with some methane
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and some form of haze, and it displays an active surface of geysers that spout
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an unknown subsurface material.</p>
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<p >Nereid, the second satellite, has a diameter of only about 320 km. Neptune is
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also circled by five thin rings. Further, its magnetic field is tilted more than
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50 degrees to the rotation axis.</p>
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</body>
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</html>
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