NEPTUNE Mario Goni, Emily Garcia, Samantha Castillo

NEPTUNE  Neptune is the 8 th planet from the sun at 2.8 billion miles away.  It has a radius of 15,299 miles.  It has 5 rings, and 13 moons.  Neptune is blue/green in color and is known for having it’s Great Dark Spot.  It is the last hydrogen/helium gas giant in the solar system.

NEPTUNE’S FORMATION  There are two possible ways Neptune was formed, the more logical and modern one being called the disk instability model.  In this process, clumps of dust and gas are bound together early in the life of the solar system.  Over time, they combine to form into a giant planet.  This could take as little as a thousand years, allowing time for the planet to trap the rapidly-vanishing lighter gases and avoid a warm death by the sun.

INTERIOR  Onions have layers, so do planets  Neptune’s interior consists of mainly helium, hydrogen and methane.  The inner core is suspected to be made of a rocky iron or rock and ice.  It also has the greatest portion of core per planet size.  The mantle is an icy liquid including water, ammonia, and methane ices.  The crust/atmosphere is made of fluid hydrogen, helium and methane.  Neptune’s upper atmosphere is made of clouds.

NEPTUNE’S INTERIOR

EXTERIOR  The atmosphere is made up mostly of hydrogen, helium and methane.  The upper atmosphere contains some white clouds of frozen methane.  These appear as continually changing bands between the equator and the poles of Neptune.  It has a very active weather system with an average surface temperature of -225 degrees Celsius, the coldest in the solar system.  It has the solar system’s strongest winds, exceeding 1000 km.

EXTERIOR CONT.  Diameter: 49,530 km or 3.9 times Earth’s diameter  Density: 1.6 g/cm^3 or 30% of Earth’s surface density  Surface Gravity: 1.2 times Earth’s surface gravity  The poles are tipped over at 47 degrees, and has a magnetic field 27 times more powerful than earth’s causing wild swings during each rotation.  It is the smallest gas giant in the whole solar system.  Neptune is blue/green in color.  The planet can not sustain life as we know it.

RINGS  Neptune has 5 rings called Galle, Le Verrier, Lassell, Arago, and Adams, named after the astronomers who each made an important discovery about the planet.  The rings contain 20-70% dust, and small rocks.  The rings are very difficult to see because they are so dark, and vary in density and size.  It is believed the rings are very young for the planet and were probably formed when a moon traveled too close to Neptune and was torn apart by gravity.

RINGS CONT.  The Galle ring is the closest at 41,000-43,000 km away from Neptune.  The La Verrier ring is very narrow, only about 113 kilometers wide.  The Lessell ring is the widest of Neptune’s rings, at 4,000 km wide, 53,200-57,200 km from Neptune.  The Arago ring is 57,200 km from the planet and only 100 km wide.

THE ADAMS RING  The very outer ring, Adams, is narrow at only 35 km wide, yet still the most famous because of its 5, law defying arcs.  Adam’s arcs are areas where the materials of the ring are clumped together.  The three most famous of the arcs are Equality, Liberty, and Fraternity.  The arcs are the brightest parts of the rings and were the first to be discovered.  Scientists are unable to explain the arcs because according to the laws of motion, the materials should have been distributed uniformly through the rings.

NEPTUNE’S RINGS In 2005 it was discovered that the rings are much more unstable than originally thought, and some are actually dwindling away rapidly.

ORBIT  Neptune has an orbital period of 165 years/60,190 Earth days.  Recently completed its first orbit in 2011 since its original discovery in  It has a day length of 16 hours and 6 minutes.  At some points during its rotation, Pluto is actually closer to the sun and Earth than Neptune, since Pluto has an unusual elliptical orbit.

NEPTUNE’S ORBIT

UNIQUE CHARACTERISTICS  First, it is the last non-controversial planet in the solar system, yet discovered  Once Uranus had been discovered, perturbations in its orbit were seen. Calculations were made and it was predicted, that there should be a planet within a certain patch of sky. Within hours, Neptune was discovered in  This makes it the first planet to be discovered by mathematical calculations

NEPTUNE’S MOONS  Neptune has 13 official moons and one awaiting confirmation.  They are all named after lesser sea gods and nymphs from Greek mythology: Triton, Nereid, Naiad, Larissa, Proteus, Galatea, Thalassa, Despina, Halimede, Neso, Psamathe, Laomedeia and Sao.  There are six inner moons, two large center moons and 5 outer moons.

THE INNER MOONS  The inner moons consist of Naiad, Thalassa, Despina, Galatea, Larissa, and Proteus.  Naiad is 36 miles in diameter.  Thalassa is 50 miles in diameter.  Despina is 92 miles in diameter.  Galatea is 98 miles in diameter.  Larissa is 120 miles in diameter.  Proteus is 260 miles in diameter.

THE CENTER MOONS  Triton is 1,677 miles in diameter and is the largest of the moons, discovered in the same year as Neptune.  It is the only spherical moon of Neptune.  It is one of the 4 moons known to have an actual atmosphere and is the only moon of Neptune’s to have a retrograde orbit. This suggests that it may have been a dwarf planet that was captured into orbit by Neptune.  In 2010, seasons were discovered on Triton.  Scientists fear that Neptune’s gravity is pulling Triton closer to the planet, and eventually it will be torn apart.

TRITON

THE CENTER MOONS CONT  Nereid is the third largest moon, behind Proteus (260 miles), at 211 miles in diameter.  It is also one of the largest irregular moons in the solar system.  This means it has an orbit that is highly inclined to the planets equator.

NEREID

THE OUTER MOONS  The outer moons consist of Halimede, Sao, Laomedia, Neso and Psamathe.  Halimede has a diameter of 19 miles.  Sao has a diameter of 12 miles.  Laomedia has a diameter of 12 miles.  Neso has a diameter of 19 miles.  Phamathe has a diameter of 12 miles.

NEW MOON?  A new possible moon was discovered in 2013 orbiting 65, 400 miles away from Neptune.  It is expected to be no more than 12 miles across, making it the smallest moon to orbit Neptune. It completes one revolution around Neptune every 23 hours.  It is so tiny that it was even overlooked while the Voyager 2 spacecraft flew by in 1989 to survey the planet’s system of moons and rings..  It still has to wait for discovery conformation before it can be considered the official 14 th moon.

THE GREAT DARK SPOT  It is a depression in the atmosphere surrounded by high cirrus clouds.  A few years after the Voyagers found it, it had disappeared (Hubble Space Telescope). Then, in 1995, it reappeared in Neptune's northern hemisphere.  However, Neptune's Great Dark Spot does not appear to be stable.  When the Great Dark Spot was first discovered, it was thought to be moving very slowly. It wasn’t until Neptune's rotation rate was finally determined, that we realized the Great Dark Spot wasn't actually moving slowly with the planet, but instead was moving in a direction opposite the planet's spin, at almost supersonic speeds. These are ten times hurricane speeds on Earth.

THE GREAT DARK SPOT

TARGET QUESTIONS a giant storm.  17:Neptune’s Great Dark Spot was a giant storm. orbits the sun.  23: Kepler’s second law states that equal areas are covered in equal amounts of time as an object orbits the sun. Neptune  26: Which of the following planets is similar to Uranus in terms of its size and mass? Neptune

VIDEOS  Sounds of Neptune:  Ten Facts:  Neptune song (so sorry):