Uranus

Uranus Average distance from the sun = about 1 billion 710 million miles (1,710,000,000) 1 year = 84 Earth years 1 day = 17.24 Earth hours Radius = 4 times Earth’s radius Mass = 14.5 times Earth’s mass Average temp at cloud tops = -330 F Atmospheric composition 82.5% Hydrogen 15.2% Helium 2.3% methane Some water vapor

Uranus The 4th most massive planet in the Solar system Discovered in 1781 with the aid of a telescope Like Saturn and Jupiter, it has belts and zones Methane and water vapor form ice crystals in the cloud tops Methane absorbs red light, giving Uranus its blue-green color

A Unique axis of rotation

Its axis of rotation is tilted 98o This produces dramatic seasons It also rotates on its axis in a clockwise direction (like Venus) Recall this is called retrograde motion It may have been part of a massive collision that caused the axis to tilt in this way

The Interior of Uranus The interior most likely is separated into 3 distinct layers Outer layer: liquid Hydrogen and Helium Middle layer: highly compressed water Some methane and ammonia Inner core is dense rock

Rings and Moons of Uranus Uranus has 10 known rings They were discovered accidentally when they blocked the light from a star behind it This is known as occultation They orbit in the plane of the equator Most of its moons orbit in this plane also There are 5 major moons ( of 27 total known) They from 480-1600km in diameter

Miranda Miranda is the smallest of the 5 major moons After a high energy impact, large pieces of the moons ice-rock crust broke off Eventually they were gravitationally attracted back to the planet Today, we see a patchy surface

Neptune

Neptune The 3rd largest planet in the solar system Very similar to Uranus It is blue in color and has belts and zones High wind speeds Up to 2000 km/hr Rotational axis is tilted 30 degrees

Key Stats Average distance from the sun = 2 billion 700 million miles (2,700,000,000) 1 year = 164.8 Earth years 1 day = 16.11 hours 17.1 times the mass of Earth Radius is 24,764 km (3.88 times larger than Earth’s radius Average temp at cloud tops -360F Atmospheric composition 79% Hydrogen 18% Helium 3% methane

The Discovery of Neptune Neptune was predicted to exist by looking at the orbit of Uranus Uranus was moving slightly different than should have been according to Newton’s laws of motion This was due to the gravitational influence of Neptune

Neptune’s atmosphere Belts and zones show differential rotation There are also storm systems The Great Dark Spot Methane ice crystals have been detected in the upper cloud layer giving Neptune a blue-green color

Neptune’s interior Very similar to the interior of Uranus The interior most likely is separated into 3 distinct layers Outer layer: liquid Hydrogen and Helium Middle layer: highly compressed water Some methane and ammonia Inner core is dense rock

Rings and Moons of Neptune Neptune also has rings They are similar to those of Uranus Low albedo Thin It has 13 known moons Most are captured objects Triton is the largest

Triton Has a retrograde orbit Is most likely a mixture of rock and ice Has a thin Nitrogen atmosphere Tidal forces from Neptune may has melted the interior They may also have changed its surface features It appears to have frozen lakes and ice geysers expelling nitrogen Plumes of gas 8 km high have been observed It surface temp is -395F The coldest body yet studied

The Roche Limit If an moon gets too close to a planet, it can be pulled apart This specific distance is called the Roche limit Triton is slowly drifting closer to Neptune Eventually, it will breech the Roche limit and be destroyed Its pieces will most likely end up as a ring around Neptune