Page 55 - Curriculum Visions Dynamic Book

The core
Neptune is the densest of the giant planets, being almost a third as dense as the Earth. This must mean that it has a larger than usual core, probably made from melted ice and molten rock.
Neptune, like Uranus, has a magnetic field that is produced not from its core, as on the Earth or Jupiter or Saturn, but from a region closer to the cloud tops. At the moment there is no clear explanation for why this should be.
The magnetic field traps few charged particles, and so it has none of the spectacular auroras that are a feature of the larger gas giants.
Satellites and rings
From Earth-bound telescopes only two moons can be seen—Triton and Nereid. Voyager’s encounter found six others (Naiad, Thalassa, Despina, Galatea, Larissa, and Proteus), all between the surface of Neptune and Triton. Proteus is 400 km across; the others are each about 200 km across.
molten rock
absolute zero The coldest possible temperature, defined as 0 K or –273°C.
atmospheric pressure The pressure on the gases in the atmosphere caused by gravity pulling them toward the centre of a celestial body.
aurora A region of illumination, often in the form of a wavy curtain, high in the atmosphere of a planet.
core The central region of a body. latitude Angular distance north or south
of the equator, measured through 90°.
magnetic field The region of influence of a magnetic body.
pressure The force per unit area.
Gas
Melted ice and
 Neptune’s two bright rings have material throughout their orbit and are continuous. The faint inner ring can also be seen.
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