The Outer Planets
Outer Planets
• Jupiter, Saturn, Uranus and Neptune.
• The four outer planets are large, low density and
gaseous with small rocky cores.
• All have thick hydrogen and helium atmospheres.
• The planets have several moons.
• All have rings made of ice and rocks.
• Known as Jovian or giant planets.
Jupiter
• Distance from the sun:
778,340,821 km
• Origin of Name:
the Roman king of the gods
• Size (in diameter):
139,822 km
• Interesting Fact:
Rotates faster than any planet in the Solar System, one day is less than 10 hours.
Jupiter
• Jupiter has a huge magnetic field, much stronger than Earth's, which extends past the orbit of Saturn. • Jupiter's colorful cloud bands are
composed of ammonia and
ammonia compounds. Jupiter's fast rotation creates strong jet streams, smearing its clouds into bands
across the planet.
• Jupiter has faint rings composed of small grains of rock, but no ice.
• In Roman mythology, Jupiter (known as Zeus in Greek mythology) was the king of the gods.
• Jupiter is the largest planet in the solar system. Jupiter is more than twice as massive as all the other planets combined.
• Jupiter has at least 67 moons. Most of these moons are very small, and were probably once asteroids that got too close and were captured by Jupiter’s gravity. The largest and most interesting of its moons are Io, Europa,
Ganymede and Callisto.
• This giant planet has no solid surface but scientists think it has a solid inner core about the size of Earth. Its atmosphere is similar to that of the Sun - mostly hydrogen and helium. The atmosphere slowly gets thicker and thicker until the increasing heat and pressure condenses the gases into an ocean of liquid metallic hydrogen.
Great Red Spot
• Jupiter's Great Red
Spot is a giant
hurricane, over twice
the size of Earth.
• The storm was
discovered by Galileo
nearly 400 years ago.
• With no surface to
slow them down,
Jupiter’s spots can
persist for many
years.
Jupiter’s Moons
• Jupiter’s largest moons are also known as Galilean moons after Galileo Galilei who discovered them in 1610.
• Ganymede
, the largest moon in the solar system (larger than Mercury), has an icy surface cut by fractures and impact craters. It is the only moon known to have its own magnetic field.• Callisto
has the oldest, most cratered surface of any body yet observed, which serves as a visible record of the solar system’s early history.• Io
has active volcanoes which erupt a form of molten sulfur mixed with other minerals, giving it a colorful surface.• Europa
has a smooth, thin surface of ice with perhaps an ocean of slushy or liquid water beneath. It is thought to have twice as much water as the Earth.Saturn
• Distance from the Sun:
1,426,666,422 km
• Origin of Name:
The Roman god of agriculture
• Size (in diameter):
116,464 km
• Interesting Fact:
It is the least dense of all the
Saturn
• In Roman mythology, Saturn was the god of agriculture and Cronus, father of Zeus the Greek equivalent.
• Saturn has 53 moons. The largest and most interesting is Titan because it has a thick, smog-like atmosphere.
• Saturn has seven rings with several gaps and divisions made mostly of water ice and very little rocky material. Its rings are 169,800 miles wide, but less thick than a football field.
• Saturn’s atmosphere is very similar to Jupiter’s. It’s mostly hydrogen with
clouds of methane and helium. The sky gradually turns into liquid until it
becomes a giant ocean of liquid metallic hydrogen.
• Winds in the upper atmosphere which can reach 500 m/s combine with heat rising from the planet’s interior to cause the yellow and gold bands visible in the atmosphere.
• Saturn is furthest planet from Earth that can be observed without a telescope.
North Pole Hexagon
• Saturn’s hexagon is a
persisting hexagonal
cloud pattern around
the north pole first
discovered by the
Voyager 1 spacecraft.
• The hexagon forms
where there is a steep
change in the speed
of the winds from the
interior to the outer
atmosphere of the
planet.
Saturn’s Moons
• Saturn’s largest moon, Titan, is a bit larger than the planet Mercury.
• Titan is shrouded in a thick, nitrogen-rich smog that might be similar to what
Earth's atmosphere was like long ago before life. The Huygens spacecraft discovered large methane/ethane lakes when it landed on the moon’s surface in 2005.
• Saturn’s much smaller, moon Enceladus, has smooth icy areas which
indicate that liquid water may be present beneath the surface. The icy surface also makes it very reflective and one of the brightest objects in the solar
system.
• Enceladus’ polar region is cut by long fractures called “tiger stripes”, some of which emit jets of water vapor and dust.
Uranus
• Distance from the Sun:
2,870,658,186 km
• Origin of Name:
The Greek god of the sky
• Size (in diameter):
50,724 km
• Interesting Fact:
The moons of Uranus are named after characters from the works of William Shakespeare and
Uranus
• Uranus spins on its side - angle of rotation is 98˚. It is believed that long ago a very large Earth-sized object smashed into the
planet. The crash was so powerful that it knocked the planet on its side and
completely changed the direction of Uranus' spin.
• Its atmosphere is mostly hydrogen and
helium with only 2% methane which is what makes Uranus look greenish-blue.
• Uranus is an ice giant. More than 80% of its mass is made up of a hot dense fluid of “icy” materials – water, methane and ammonia. • For a long time, astronomers didn't think the
planet had rings and they were discovered by accident. The rings are made of dark carbon stuff which does not reflect light. • The planet is almost featureless with very
little weather.
• In Roman mythology, Uranus was the lord of the skies and husband of Earth. He was also the king of the gods until his son Saturn overthrew him.
• Uranus has 27 moons. Five of these moons are large, and the rest are smaller.
• The planet rotates clockwise while all the other planets (except Venus) and all the moons spin counterclockwise.
Neptune
• Distance from the Sun:
4,498,396,441 km
• Origin of Name:
The Roman god of the sea
• Size (in diameter):
49,324 km
• Interesting Fact:
In 2011, Neptune completed it’s first orbit since its discovery in 1846.
Neptune
• Neptune's winds are the fastest in the solar system, reaching 2000 km/hour or nine times stronger than Earth’s.
• Neptune has six rings which circle the planet.
• It’s a sister ice giant to Uranus. Neptune’s atmosphere gradually
becomes a very thick, hot combination of water, ammonia and methane.
• Neptune also gets its bright blue color from methane.
• Because dwarf planet Pluto’s orbit is so eccentric, it crosses the orbit of Neptune for a 20-year period.
• In Roman mythology, Neptune was originally only the god of water, but was later extended to the ocean when he became associated with the Greek god Poseidon.
• For many centuries people did not know that this planet even existed.
Astronomers observed that Uranus’ orbit was not where is should be and they thought there must be another planet disturbing its orbit. So the search began and Neptune was discovered in 1846 (Uranus was discovered in 1781).
Neptune was the first planet located through mathematical predictions rather than through regular observations.
