Breaking the Ice with Uranus and Neptune

• Uranus and Neptune’s important characteristics:

  • They are comparable in size and chemical makeup.

  • They are both smaller and denser than Jupiter and Saturn.

  • A tiny system of moons and rings surrounds each planet, which serves as its center.

  • Each planet exhibits evidence of an earlier collision with a large body.

• Uranus and Neptune are also known as ice giants because their atmospheres surround cores of rock and water.

• The water is a hot liquid because it is so deep inside Uranus and Neptune and is under such intense pressure.

• Uranus’s equatorial diameter is 31,770 miles.

• Neptune’s equatorial diameter is 30,775 miles.

• The fact that Uranus appears to have turned on its side is proof positive that the planet was involved in a significant collision or gravitational encounter.

  • During roughly one-fourth of Uranus' 84-year orbit around the Sun, the North Pole faces roughly the Sun, while roughly the other one-fourth of the time, the South Pole faces roughly the Sun.

  • During the remaining time, the Sun illuminates the entire range of latitudes from pole to pole.

• The planet Uranus has a ring system and 27 known moons.

  • The rings are composed of an extremely dark substance, most likely carbon-rich rock, similar to some meteorites called carbonaceous chondrites.

• Neptune's axis is tilted 28° from the perpendicular to its orbit plane.

• Neptune has 14 known moons.

  • Triton: Neptune’s largest moon — which is larger than Pluto.

• Neptune’s atmosphere features cloud belts, and occasionally a so-called Great Dark Spot appears, which may be a very large storm.

Pluto

• Pluto moves inside the orbit of Neptune every 248 years for a few decades at a time, but the last such inside move ended in early 1999.

• Pluto's orbit around the Sun is direct.

• Pluto is massive enough that their own gravity makes them round.

• Pluto is tilted for about 120° from the plane of its orbit.

• Pluto is 1,475 miles in diameter.

• Pluto takes 6 days, 9 hours, and 18 minutes to turn once on its axis.

• Pluto is mostly made of rock, but it is all buried deeply. A thick layer of water ice covers the surface. Rather than granite, frozen water makes up Pluto's bedrock.

• Between the rock interior and the ice shell surface layer is probably an underground ocean.

• Some dark areas on Pluto are coated with tholins — chemical substances produced when methane particles or other hydrocarbons are struck by ultraviolet light from the sun and by galactic cosmic rays.

• Charon: Pluto’s moon, it has a huge reddish-brown polar cap, which was probably created when gas that broke free from Pluto's atmosphere fell onto the massive moon and was exposed to cosmic rays and ultraviolet radiation, which created tholins.

• Pluto has no additional moons that New Horizons could discover and no discernible rings.

• Over 20 haze layers were discovered by New Horizon in its atmosphere. It also studied the known moons, hunted for additional moons, and looked for signs of a ring around the dwarf planet.

• Tombaugh Regio: It is a sizable region that essentially resembles a heart-shaped box of Valentine's Day sweets and is named after the late American astronomer Clyde Tombaugh, who discovered Pluto.

  • Sputnik Planitia: The west lobe of the region which is brighter and smooth.

  • There are no craters on Sputnik Planitia, at least none that are visible at the resolution of the images.

  • Tombaugh Regio's eastern lobe is clearly cratered; a large portion of it is about 1 billion years old.

  • The areas of Pluto that are farther from the Heart are heavily cratered and, in some places, mountainous, and they are about 4 billion years old.

Kuiper Belt

• These are 100,000 icy bodies in the region between Neptune's orbit and 50 AU from the Sun.

• It is named after the astronomer — Gerald Kuiper.

• Their orbits are very elliptical.

• Their orbital planes differ significantly from the plane of the Earth's orbit in terms of tilt.

• They take about the same amount of time to complete two full orbits around the Sun as Neptune does to complete three.

• Since their orbits cross, it prevents Pluto and Neptune from ever colliding.