Ice giants: Uranus and Neptune

This article is from
Creation 44(2):34–37, April 2022

Browse our latest digital issue Subscribe

Creation for kids—Ice giants: Uranus and Neptune

by Jonathan Sarfati

Published in Creation 44(2):34–37, 2022

Fast facts

Uranus is tipped on its side!
Uranus’s diameter is 4.01 times that of Earth, and 63 Earths could fit inside it. But Uranus has only 14.54 times Earth’s mass because of its light materials.
Uranus’s ‘day’ (rotation on its axis) is 17 hours, 14.5 minutes. Its ‘year’ (time to revolve around the sun) is 84 years—or 42,718 Uranian ‘days’!
Uranus is 19.2 times further from the sun than Earth, i.e. 19.2 astronomical units (AU) away. Its atmosphere is the coldest of the planets in our system, an unimaginably chilly 49 K (−224 °C, −371 °F).
Uranus has strong winds of 900 km/hr (560 mph). Uranus has 13 fairly large moons and 22 tiny ones. It also has some thin rings. The orbits of the moons and rings are tipped sidewise like the planet.
Neptune’s diameter is about 3.88 times that of Earth, and 58 Earths could fit inside it. But it is only 17.15 times as massive as Earth. So Neptune is a bit smaller but a bit heavier than Uranus.
Neptune’s day is 16 hr 6.5 min, and its year is 164.8 Earth years, or 89,666 Neptunian days. Neptune is 30.07 AU from the sun. So it is frigid: 55 K (−218 °C, −360 °F)—but not as cold as Uranus.
Neptune has the fastest sustained winds in the whole solar system. They can reach 2,100 km/hr (1,300 mph). Neptune has a long-lasting storm called the Great Dark Spot, about as wide as the whole earth!
Neptune has one large moon, Triton, and 13 tiny moons. Triton orbits Neptune backwards (retrograde) and has the most circular orbit in the solar system. Neptune also has five thin rings.

uranus-and-four-rings — Uranus and its four major rings (Hubble telescope computerized image)

Discovery

Ancient people knew and named six of the eight planets in our solar system. But Uranus and Neptune are much further away and need powerful telescopes to be seen properly. The German-British astronomer William Herschel (1738–1822) discovered Uranus in 1781. People had seen it before, but they thought it was a very faint star. Herschel realized that it was a planet.

Then astronomers tracked its motion. By this time, the brilliant creationist scientist Isaac Newton (1642–1727) had proposed his laws of motion and gravity. The French astronomer Urbain Le Verrier (1811–1877) observed that Uranus’s motion was a little strange. He realized that there must be a large unseen object’s gravity pulling Uranus slightly. He worked out the position and sent it to Johann Gottfried Galle (1812–1910) at the Berlin observatory. The same night that Galle received the letter, he aimed the observatory’s powerful telescope at the position. He found Neptune just 1° from Le Verrier’s prediction. This was an amazing triumph for Newton’s theories.

Icy

Uranus and Neptune are much smaller than Jupiter and Saturn but much bigger than Earth. Jupiter and Saturn are called ‘gas giants’ because they are mainly made of hydrogen and helium. These stay gaseous even at the ultra-cold temperatures of space. But while Uranus and Neptune are also mostly hydrogen and helium, they also contain water, methane, and ammonia. The last three substances freeze at the temperatures of deep space. So Uranus and Neptune are called ‘ice giants’. The methane gives these planets an attractive blue colour—pale greenish blue for Uranus, bright blue for Neptune.

uranus-neptune-neptune — **Left:** Uranus from the 1986 Voyager 2 fly-by.
**Middle:** Neptune from Voyager 2 showing its Great Dark Spot.
**Right:** Neptune’s Great Dark Spot closer-up with accompanying high-altitude clouds.

Monuments to creation

How could they form? Evolutionists say that the sun and planets formed from a collapsing cloud of dust and gas. But there would be very little material so far away from the sun, and it would move very slowly. So some evolutionists say that Uranus and Neptune should not exist under their model. But they do exist, because God created them on Day 4 of Creation Week.

Uranus and especially Neptune give off more heat than they receive from the sun. That is why Neptune is a bit warmer despite being further from the sun. The heat also powers the strong winds on these planets. But if the planets were billions of years old, the heat source would have run out long ago.

Back in 1984, evolutionists predicted that these planets would have very weak magnetic fields. They believe that the planets are billions of years old, so they could not sustain a strong field. But the Bible teaches that God created the planets only about 6,000 years ago. Creationist physicist Dr Russell Humphreys proposed that God created planets with a field, which decayed over time. From this, he predicted that Uranus would have a field 100,000 times stronger. When the Voyager 2 satellite measured Uranus’s field in 1986, it confirmed Dr Humphreys’ prediction.

Activity

Ask your parents if they have binoculars. Try to find Uranus and Neptune in the night sky. Some smartphone apps could show you where they are, such as Sky Map.