THE SCIENCE SPECTRUM: Planets in the Solar System--- NEPTUNE: My Blue World

Neptune is the eighth planet from the Sun and the fourth largest (by diameter). Neptune is smaller in diameter but larger in mass than Uranus. Its color is blue and it has Neptune has 13 known moons; 7 small named ones and Triton plus four discovered in 2002 and one discovered in 2003

orbit: 4,504,000,000 km (30.06 AU) from Sun

diameter: 49,532 km (equatorial)

mass: 1.0247e26 kg

Neptune's Satellites

Distance Radius Mass Satellite (000 km) (km) (kg) Discoverer Date --------- -------- ------ ------- ---------- ----- Naiad 48 29 ? Voyager 2 1989 Thalassa 50 40 ? Voyager 2 1989 Despina 53 74 ? Voyager 2 1989 Galatea 62 79 ? Voyager 2 1989 Larissa 74 96 ? Voyager 2 1989 Proteus 118 209 ? Voyager 2 1989 Triton 355 1350 2.14e22 Lassell 1846 Nereid 5509 170 ? Kuiper 1949 Halimede 15728 61 ? 2002 Sao 22422 40 ? 2002 Laomedeia 23571 40 ? 2002 Psamathe 46695 38 ? 2003 Neso 48387 60 ? 2002

Read more about Neptune l Neptune facts, pictures and information. by nineplanets.org Distance Radius Mass Satellite (000 km) (km) (kg) Discoverer Date --------- -------- ------ ------- ---------- ----- Naiad 48 29 ? Voyager 2 1989 Thalassa 50 40 ? Voyager 2 1989 Despina 53 74 ? Voyager 2 1989 Galatea 62 79 ? Voyager 2 1989 Larissa 74 96 ? Voyager 2 1989 Proteus 118 209 ? Voyager 2 1989 Triton 355 1350 2.14e22 Lassell 1846 Nereid 5509 170 ? Kuiper 1949 Halimede 15728 61 ? 2002 Sao 22422 40 ? 2002 Laomedeia 23571 40 ? 2002 Psamathe 46695 38 ? 2003 Neso 48387 60 ? 2002

Read more about Neptune l Neptune facts, pictures and information. by nineplanets.org

Distance Radius Mass Satellite (000 km) (km) (kg) Discoverer Date --------- -------- ------ ------- ---------- ----- Naiad 48 29 ? Voyager 2 1989 Thalassa 50 40 ? Voyager 2 1989 Despina 53 74 ? Voyager 2 1989 Galatea 62 79 ? Voyager 2 1989 Larissa 74 96 ? Voyager 2 1989 Proteus 118 209 ? Voyager 2 1989 Triton 355 1350 2.14e22 Lassell 1846 Nereid 5509 170 ? Kuiper 1949 Halimede 15728 61 ? 2002 Sao 22422 40 ? 2002 Laomedeia 23571 40 ? 2002 Psamathe 46695 38 ? 2003 Neso 48387 60 ? 2002

Read more about Neptune l Neptune facts, pictures and information. by nineplanets.org

Distance Radius Mass Satellite (000 km) (km) (kg) Discoverer Date --------- -------- ------ ------- ---------- ----- Naiad 48 29 ? Voyager 2 1989 Thalassa 50 40 ? Voyager 2 1989 Despina 53 74 ? Voyager 2 1989 Galatea 62 79 ? Voyager 2 1989 Larissa 74 96 ? Voyager 2 1989 Proteus 118 209 ? Voyager 2 1989 Triton 355 1350 2.14e22 Lassell 1846 Nereid 5509 170 ? Kuiper 1949 Halimede 15728 61 ? 2002 Sao 22422 40 ? 2002 Laomedeia 23571 40 ? 2002 Psamathe 46695 38 ? 2003 Neso 48387 60 ? 2002

Distance Radius Mass

Satellite (000 km) (km) (kg) Discoverer Date

Naiad 48 29 ? Voyager 2 1989

Thalassa 50 40 ? Voyager 2 1989

Despina 53 74 ? Voyager 2 1989

Galatea 62 79 ? Voyager 2 1989

Larissa 74 96 ? Voyager 2 1989

Proteus 118 209 ? Voyager 2 1989

Triton 355 1350 2.14e22 Lassell 1846

Nereid 5509 170 ? Kuiper 1949

Halimede 15728 61 ? 2002

Sao 22422 40 ? 2002

Laomedeia 23571 40 ? 2002

Psamathe 46695 38 ? 2003

Neso 48387 60 ? 2002

Neptune's Rings

Distance Width

Ring (km) (km) aka

Diffuse 41900 15 1989N3R, Galle

Inner 53200 15 1989N2R, LeVerrier

Plateau 53200 5800 1989N4R, Lassell, Arago

Main 62930 < 50 1989N1R, Adams

(distance is from Neptune's center to the ring's inner edge)

Neptune is one of the most unique planets in the solar system that is why it is one of my favorite planets.

A new article in the journal Nature Physics says that there could be oceans of liquid diamonds with floating diamond icebergs on Neptune and Uranus.

The research, based on the first detailed measurements of the melting point of diamond, found diamond behaves like water during freezing and melting, with solid forms floating atop liquid forms. The surprising revelation gives scientists a new understanding about diamonds and some of the most distant planets in our solar system.

“Diamond is a relatively common material on Earth, but its melting point has never been measured,” said Eggert. “You can’t just raise the temperature and have it melt, you have to also go to high pressures, which makes it very difficult to measure the temperature.”

Other groups, notably scientists from Sandia National Laboratories, successfully melted diamond years ago, but they were unable to measure the pressure and temperature at which the diamond melted.

Diamond is an incredibly hard material. That alone makes it difficult to melt. But diamond has another quality that makes it even harder to measure its melting point. Diamond doesn’t like to stay diamond when it gets hot. When diamond is heated to extreme temperatures it physically changes, from diamond to graphite.

The graphite, and not the diamond, then melts into a liquid. The trick for the scientists was to heat the diamond up while simultaneously stopping it from transforming into graphite.

Eggert and his colleagues took a small, natural, clear diamond, about a tenth of a carat by weight and half a millimeter thick, and blasted it with lasers at ultrahigh pressures like those found on gas giants like Neptune and Uranus.

The scientists liquefied the diamond at pressures 40 million times greater than what a person feels when standing at sea level on Earth. From there they slowly reduced the temperature and pressure.

When the pressure dropped to about 11 million times the atmospheric pressure at sea level on Earth and the temperature dropped to about 50,000 degrees, solid chunks of diamond began to appear. The pressure kept dropping, but the temperature of the diamond remained the same, with more and more chunks of diamond forming.

Then the diamond did something unexpected. The chunks of diamond didn’t sink. They floated. Microscopic diamond ice burgs floated in a tiny sea of liquid diamond. The diamond was behaving like water.

After the discovery of Uranus, it was noticed that its orbit was not as it should be in accordance with Newton's laws. It was therefore predicted that another more distant planet must be perturbing Uranus' orbit. Neptune was first observed by Galle and d'Arrest on 1846 Sept 23 very near to the locations independently predicted by Adams and Le Verrier from calculations based on the observed positions of Jupiter, Saturn and Uranus. An international dispute arose between the English and French (though not, apparently between Adams and Le Verrier personally) over priority and the right to name the new planet; they are now jointly credited with Neptune's discovery. Subsequent observations have shown that the orbits calculated by Adams and Le Verrier diverge from Neptune's actual orbit fairly quickly. Had the search for the planet taken place a few years earlier or later it would not have been found anywhere near the predicted location.

More than two centuries earlier, in 1613, Galileo observed Neptune when it happened to be very near Jupiter, but he thought it was just a star. On two successive nights he actually noticed that it moved slightly with respect to another nearby star. But on the subsequent nights it was out of his field of view. Had he seen it on the previous few nights Neptune's motion would have been obvious to him. But, alas, cloudy skies prevented obsevations on those few critical days.

Neptune has been visited by only one spacecraft, Voyager 2 on Aug 25 1989. Much of we know about Neptune comes from this single encounter. But fortunately, recent ground-based and HST observations have added a great deal, too.

Because Pluto's orbit is so eccentric, it sometimes crosses the orbit of Neptune making Neptune the most distant planet from the Sun for a few years.

Neptune's composition is probably similar to Uranus': various "ices" and rock with about 15% hydrogen and a little helium. Like Uranus, but unlike Jupiter and Saturn, it may not have a distinct internal layering but rather to be more or less uniform in composition. But there is most likely a small core (about the mass of the Earth) of rocky material. Its atmosphere is mostly hydrogen and helium with a small amount of methane.

Neptune's blue color is largely the result of absorption of red light by methane in the atmosphere but there is some additional as-yet-unidentified chromophore which gives the clouds their rich blue tint.

Like a typical gas planet, Neptune has rapid winds confined to bands of latitude and large storms or vortices. Neptune's winds are the fastest in the solar system, reaching 2000 km/hour.

Like Jupiter and Saturn, Neptune has an internal heat source -- it radiates more than twice as much energy as it receives from the Sun.

At the time of the Voyager encounter, Neptune's most prominent feature was the Great Dark Spot (left) in the southern hemisphere. It was about half the size as Jupiter's Great Red Spot (about the same diameter as Earth). Neptune's winds blew the Great Dark Spot westward at 300 meters/second (700 mph). Voyager 2 also saw a smaller dark spot in the southern hemisphere and a small irregular white cloud that zips around Neptune every 16 hours or so now known as "The Scooter" (right). It may be a plume rising from lower in the atmosphere but its true nature remains a mystery.

However, HST observations of Neptune (left) in 1994 show that the Great Dark Spot has disappeared! It has either simply dissipated or is currently being masked by other aspects of the atmosphere. A few months later HST discovered a new dark spot in Neptune's northern hemisphere. This indicates that Neptune's atmosphere changes rapidly, perhaps due to slight changes in the temperature differences between the tops and bottoms of the clouds.

Neptune also has rings. Earth-based observations showed only faint arcs instead of complete rings, but Voyager 2's images showed them to be complete rings with bright clumps. One of the rings appears to have a curious twisted structure (right).

Like Uranus and Jupiter, Neptune's rings are very dark but their composition is unknown.

Neptune's rings have been given names: the outermost is Adams (which contains three prominent arcs now named Liberty, Equality and Fraternity), next is an unnamed ring co-orbital with Galatea, then Leverrier (whose outer extensions are called Lassell and Arago), and finally the faint but broad Galle.

Neptune's magnetic field is, like Uranus', oddly oriented and probably generated by motions of conductive material (probably water) in its middle layers.

Neptune can be seen with binoculars (if you know exactly where to look) but a large telescope is needed to see anything other than a tiny disk. There are several Web sites that show the current position of Neptune (and the other planets) in the sky, but much more detailed charts will be required to actually find it. Such charts can be created with a planetarium program.