Neptune Facts

Neptune Facts Summary

Neptune is the planet located farthest from the Sun in our solar system. New Neptune facts constantly fascinate us as they continue to be revealed. As recently as 1989, Voyager 2 confirmed one of the most recently discovered Neptune facts, namely that Neptune, like Uranus and Saturn, has rings.

Neptune is a lot like Uranus and the other gas giants, Jupiter, and Saturn. Neptune and Uranus are further classified as ice giants because they have a large volume of ice compared to gas. You better wear a sweater! These Neptune facts are the cold truth about this windy and mysterious planet.

1. Neptune Gets Its Name from Roman Mythology

When scientists discovered Neptune, there was a good bit of debate over what to name this new planet. One of the earliest Neptune facts we know is that the planet was referred to as “the planet exterior to Uranus” when it was first discovered. This was due to the fact that Neptune is the next farthest planet from the Sun after Uranus.

Urbain Le Verrier, a French astronomer, predicted the location of the planet Neptune. When an observatory in Germany confirmed his calculations and established that the planet existed, he suggested the name Neptune. Others suggested the names Janus and Oceanus.

In one of the more selfish Neptune facts, Le Verrier later requested and gained support in France for naming the planet after himself, calling it Leverrier. In the hopes of gaining traction for Le Verrier’s name, French reference books changed the name of Uranus to Herschel, after William Herschel who discovered the planet.

Outside of France, other scientists did not like the idea and Neptune became the accepted name that we use today. Neptune was the Roman god of the sea, who the Romans adopted from the Greek god Poseidon. Although Uranus was named after a Greek god, most of the other planets had been given the names of Roman gods, so Neptune fit in with the pattern.

2. Galileo Almost Discovered Neptune

It’s one of the amazing historical Neptune facts that Galileo’s notes contain information on Neptune. When Galileo was observing the sky for the first time through a telescope, he noticed an object near Jupiter, but thought it was a star.

Part of the reason Galileo thought Neptune was a star is because Neptune was in retrograde at the time. This is when one of the outer planets appears to go in the opposite direction, as the Earth’s orbit takes Earth past the outer planet. This happens because we measure one year every time the Earth orbits the Sun, and it takes Neptune 165 years to orbit the Sun!

For Galileo, Neptune would have appeared relatively fixed as it went into retrograde, which explains why he thought it was a star. Had Galileo observed the sky at a different time, he may have been the first to discover the planet!

3. Neptune Affects Uranus’ Orbit

More than 200 years after Galileo peered through his telescope for the first time, more Neptune facts began to emerge. In 1821, the first tables of the orbit of Uranus were published. Astronomers began to notice that there were big differences in the orbit of Uranus, as they observed the planet compared to what they believed the predicted orbit should be.

In 1843, British scientist John Couch Adams began to make more precise calculations. With the help of the Astronomer Royal, Adams also gathered more precise observations of Uranus. Adams predicted that there was another planet that was affecting Uranus’ orbit.

From 1845 to 1846, the race was on to discover the new planet and establish the first Neptune facts. In France, Urbain Le Verrier was working separately from Adams and also predicted the appearance of another planet around the same time. Adams saw Le Verrier’s predictions and raced to get more observations and to be the first to have a confirmed sighting of the new planet.

Le Verrier’s calculations were more accurate and, on September 23, 1846, Neptune was observed and confirmed by the Berlin Observatory. The Observatory had only received Le Verrier’s letter earlier that day. That night, the first Neptune facts were established and Neptune was observed to within one degree of where Le Verrier had predicted it to be!

Uranus helped establish the first Neptune facts. It may have been some time later, after telescopes had improved more, that the planet would have been found, except for the fact the Uranus’ orbit is affected by Neptune. The gravity from Neptune counteracts the gravity of the Sun and pulls Uranus slightly from what the predicted orbit should be.

4. The Discovery of Neptune was a Big Victory for Science and Math

It’s one of the inspiring Neptune facts for kids that Le Verrier discovered Neptune using only math. Based on the calculus of Sir Isaac Newton and Gottfried Wilhem Liebniz, Le Verrier’s calculations allowed him to predict the size and location of the object that was affecting Uranus’ orbit.

It’s one of the amazing Neptune facts that Neptune was predicted not by what it looked like, but by how it affected Uranus. The mathematical prediction was confirmed through observation. Scientists love when they can confirm a theory through observation.

Discovering another planet that we did not know about for perhaps all of human history was a big victory for science and math. In the 1840s, when the first Neptune facts were established, the Industrial Age was just beginning, made possible thanks to many more discoveries through math and science.

5. Neptune is One of the Ice Giants

Neptune and Uranus seem to be linked by more than gravity. Because of Neptune’s position in the solar system, one of our Neptune facts is that it is a big ball of ice and gas, like Uranus. Jupiter, Saturn, Uranus, and Neptune are the Gas Giants. Because Neptune and Uranus have a large internal ball of liquid and ice, they are considered Ice Giants.

Giant is the right word, because Neptune is huge! Some of the massive Neptune facts include the fact that Neptune is 17 times larger than Planet Earth, and its radius is four times that of Earth’s. While it may look like a pale blue dot in the sky, Neptune is the third largest planet by mass, and more massive than Uranus.

The ice on Neptune is not like the ice we are used to here on Earth. Most of Neptune is made of a large ice and liquid mantle of methane, water and ammonia. Inside of the icy mantle on Neptune, there is a small rocky core. Another of the massive Neptune facts is that although we call it a small rocky core, that’s simply in relation to the size of the planet. Neptune’s core is actually larger than the entire Earth!

Like Uranus, there are speculations that the very base of the Neptune’s mantle may be an ocean of liquid diamond. One of the more speculative Neptune facts is also one of the most intriguing: when methane is under extreme pressure at the bottom of Neptune’s mantle, the molecules break down and carbon atoms are released. These carbon atoms form an ocean of liquid diamond. Diamond is one of the hardest known substances. An ocean of liquid diamond would certainly make for one rough day at the beach!

6. Neptune Has 14 Moons

Neptune may be a big ball of gas and ice, but that doesn’t mean it doesn’t have any friends. Shortly after Le Verrier discovered Neptune, more Neptune facts were discovered, including the discovery of Neptune’s moon Triton. William Lassell discovered Triton only 17 days after Le Verrier’s discovery. After telescopes advanced, more moons were discovered in the 1900s, bringing the total number of Neptune’s known moons to eight.

When the Voyager 2 spacecraft visited Neptune in 1989, it discovered six more moons, bringing the total to 14. Voyager 2 established more Neptune facts, including the fact that Neptune’s magnetic field is tilted from its axis of rotation, like that of Uranus. Poor Neptune is like the younger brother of Uranus, with many Neptune facts revealing the planet’s similarities with Uranus.

Neptune’s large moon Triton is much bigger than the other moons and accounts for over 90% of the mass of objects orbiting Neptune. Triton is in a retrograde orbit, which leads scientists to a mysterious Neptune fact. It appears that Neptune grabbed Triton with its gravity from a mass of objects at the edge of the solar system known as the Kuiper belt.

7. Neptune Has the Fastest Winds in the Solar System

Here’s one of the Neptune facts that show Neptune is a special planet in its own right. Voyager 2 discovered that there is an incredible weather system on Neptune that is extremely active. Giant storms that cause intense weather are visible through telescopes and are compared to the Great Red Spot on Jupiter.

Get ready for the most blistering of Neptune facts: winds on Neptune can reach speeds of over 1300 miles per hour, or over 2000 kilometers per hour! Typical wind speed is calm and peaceful, with westerly winds at over 700 miles per hour! Perhaps wearing a sweater won’t be enough! These conditions make it impossible for life, as we know it, to survive on Neptune.

8. Neptune Has Rings

Voyager 2 discovered another of our Neptune facts in 1989: Neptune has rings! Astronomers also love history, and when the rings were discovered, they used the names of the original astronomers who raced to find Neptune in 1845 and 1846.

The three main rings of Neptune are named: the Adams ring – after John Couch Adams, the Le Verrier ring – after Urbain Le Verrier, and the Galle Ring, after Johann Gottfried Galle. Galle was the first person to observe Neptune at the Berlin Observatory. Galle deserves credit for being the scientist who took the initiative and immediately looked for the planet based on Le Verrier’s calculations on the evening of the day he received Le Verrier’s letter.

Although Neptune is cold and windy, it’s one of the heartwarming Neptune facts that Le Verrier eventually got his wish and had something in the solar system named after him, though he wasn’t alive to celebrate.

9. Neptune Is Cold

We’ve established the Neptune facts about the planet’s incredibly fast winds. We know wearing a sweater can’t protect us on Neptune. Well, to make matters worse, the temperature is over 300 degrees Fahrenheit below zero, or 200 degrees Celsius below zero! Even a coat won’t be enough!

More Neptune facts will emerge as scientists continue to compare Neptune and Uranus, which have similar composition but different weather. Both are extremely cold, yet there appears to be a difference in the way that Neptune absorbs energy from the Sun. One of our surprising Neptune facts is that Neptune actually puts out more energy from the Sun than it receives! Neptune outputs over two and half times the energy it receives from the Sun.

This is another one of the mysterious Neptune facts that astronomers will continue to study. Some speculation is that there is some internal heat source radiating the energy, perhaps left over from the strong interactions that occurred when the planet was formed.

10. Neptune is the Farthest Planet from the Sun…Again

As soon as Neptune gets a moment to shine out of the spotlight of Uranus, it gets compared to Pluto! After its discovery in 1846, Neptune was considered the planet farthest from the Sun. Then, in 1930, Pluto was discovered and described as the last planet in our solar system. Neptune was then considered to be the next to last planet from the Sun.

At the end of the 20th century and the beginning of the 21st century, scientists debated whether Pluto should be included as part of the newly discovered Kuiper belt. In 2006, Pluto was reclassified as a dwarf planet. Neptune, in part because of its ability to influence the orbit of Uranus, is still considered a planet and is once again able to claim the crown of the planet farthest from the Sun!

It’s incredible to think that the planets are so far away from Earth and yet we can establish so many facts about them. It’s not surprising that telescopes and spacecraft were needed to establish Neptune facts. Neptune is over 4 billion kilometers, or over 2.5 billion miles, from the Earth and the Sun! No wonder Neptune is so mysterious. This icy and windy planet is a bit of a loner on the outer fringes of the solar system!

The good thing is that Neptune has plenty of friends — 14 moons, and three rings of objects orbit the planet. Of course, who would Neptune be without its brother, Uranus? After all, Neptune was discovered using mathematical calculations based on the changes in Uranus’ orbit. The discovery of Neptune, and the fact that Uranus is similar in composition, explains why so many Neptune facts are given in comparison to, or with reference to, Uranus. Despite any similarities, Neptune fascinates us in its own right and Neptune facts teach us more about the solar system.

Neptune Facts