1. Uranus Seventh planet from the Sun Discovered in 1781
Sidereal Period: years
Sidereal Day: 0.72 days
Average Surface Temperature: 58 K (-355 F)
17 Moons

2. Uranus 4.01 x the radius of Earth 0.23 x the density of Earth
Solid core
Ice/rock layer
Liquid hydrogen

3. Neptune Eighth planet from the Sun Discovered in 1845/1846
Sidereal Period: years
Sidereal Day: 0.67 days
Average Surface Temperature: 59 K (-353 F)
8 Moons

4. Neptune 3.88 x the radius of Earth 0.297 x the density of Earth
Solid core
Ice/rock layer
Liquid hydrogen

5. Comparing the Outer Planets