4 5 The Outer Planets What Do the

4. 5 The Outer Planets What Do the Outer Planets Have in Common? What Are the Characteristics of Each Outer Planet?

What Do the Outer Planets Have in Common? �Large �Gas giants (no solid surface)

Composition �Hydrogen and helium �Ices of ammonia and methane �Strong gravitational forces (due to their size) keep these gases from escaping �Much of the material in gas planets is actually liquid because the pressure inside the planet is so high The outer layers are extremely cold Temperature increases inward with pressure

Moons and Rings �All outer planets have many moons Jupiter: at least 63 Saturn: at least 61 Uranus: at least 27 Neptune: at least 13 �All outer planets have rings Thin disks of small particles of ice and rock Saturn’s rings are largest and most complex

What Are the Characteristics of Each Outer Planet? �Scientists are constantly discovering new information about these planets and moons (using telescopes and space probes)

Jupiter �Largest and most massive planet �Mass is 2 ½ times more than all of the other planets combined

Jupiter’s Atmosphere �Thick atmosphere (hydrogen and helium) �Great Red Spot: Storm larger than Earth! Similar to a hurricane Never ending 20, 000 km long and 12, 000 km wide

Jupiter’s Structure �Dense core of rock and iron at its center Pressure is 30 times greater than on the surface �It has a thick mantle of liquid hydrogen and helium

The Moons of Jupiter

Ganymede: Jupiter’s largest moon. (Larger than Mercury) Surface has dark and bright areas

Callisto: Second largest Less ice Most craters

Io: Not icy May have 300 active volcanoes

Europa: Ice Liquid water below the ice (possibly)

Saturn � 2 nd largest planet �Thick atmosphere (hydrogen and helium)

Saturn’s Rings �Made up of chunks of ice and rock going around Saturn �Some are kept in place from gravity of tiny moons

Saturn’s Moons �Titan (largest…larger than Mercury) Thick atmosphere (nitrogen and methane) Some features formed from flowing liquid �Mimas and Tethys: craters and trenches �Enceladus: Ice and water erupt in geysers �Phoebe: ring of material found

Uranus � 4 times diameter of Earth �Looks bluegreen due to methane in atmosphere �Rings

Uranus’s Moons �The 5 largest moons have icy, cratered surfaces

A Tilted Planet �Tilted at an angle of about 90 degrees from the vertical �The tilt is due to an object hitting Uranus and knocking it on its side �Rotation = 17 hours

Neptune �Similar to Uranus in size and color �Blue and cold �Atmosphere contains visible clouds �Interior is hot (forming clouds and storms at the surface)

Neptune’s Atmosphere �Great Dark Spot (about the size of Earth) Scientists think it is probably a giant storm that lasted a short period of time

Neptune’s Moons � 13 moons �Triton (largest) �Thin atmosphere �Nitrogen ice over south pole

THE END