Throughout my life, I’ve always admired Neptune, our furthest planet* from the sun. As a child, I would find as many books as I could about the outer gas giants, especially Neptune. I always found it the most majestic of the gas giants, with its blue hues being a welcome contrast to the incredibly ordinary Uranus, ringed wonder Saturn, or the massive and sometimes ugly, Jupiter.
But what facts set Neptune apart from the other planets, and why should we consider these facts about Neptune?
Neptune Fact # 1 : Neptune is the Smallest, Most Dense Gas Giant in Our Solar System
Not only is Neptune the furthest out of the major planets, its also the smallest of the giants, but not by much. Its approximately 3% smaller than its neighbor, Uranus. However, it is more massive than Uranus, which makes Neptune the most dense giant in our solar system. Its density is likely due to the fact it contains heavier elements compared to the other gas giants. Neptune has the lowest amount of hydrogen and more helium when compared to the other giants in our solar system. The result is a greater density, at about 1.6 grams per centimeter.
Neptune Fact #2 : Neptune Was Found by Science, Not a Telescope
The discovery of many planets in our solar system have been the result of looking up into the sky, either with eyes or telescopes. However, the discovery of Neptune is markedly different: it was discovered using mathematical models. Alexis Bouvard “discovered” the planet by completing observations of the other gas giants – Jupiter, Saturn, and Uranus – which resulted in notable discrepancies in Uranus’ orbit. Mr. Bouvard noticed that there were significant irregularities with the mathematical model, and the actual orbit of Uranus. This led him to postulate that an eighth planet existed beyond the orbit of the last known planet.
His model was absolutely correct, and his facts about Neptune were found with a telescope in September, 1843 – three years after his death. Astronomers noted that his model was able to predict the orbit of Neptune to within 1 degree – which helped them find the planet in what amounted to finding a needle in not a haystack, but a barn of hay.
Neptune Fact #3 :Neptune is Blue Because of Methane
Neptune’s color has always been fascinating to me. Its deep blue is very reminiscent of Earth’s oceans, and far more colorful than Uranus’ bluish-green color. What makes each gas giant a different color is all in what is in its atmosphere. Both Uranus and Neptune have a large amount of methane in their atmosphere, which makes them absorb red light, and reflect blue.
What would Neptune look like without the methane? One would likely have to look at Jupiter for the answer, as it is the closest planet in terms of composition, without the methane. Although, Neptune would still look very unique, as it has the most helium in its atmosphere when compared to all other planets in our solar system.
Neptune Fact #4 : Neptune’s Largest Moon Will Not Exist in the Future
Neptune is home to one of the most interesting moons in the solar system: Triton. Scientists believe that the moon is not natural to Neptune. That is, they believe that it was captured by the planet from the Kuiper Belt. Triton has a very strange retrograde orbit around the planet. This is causing it to inch closer and closer to the planet. Eventually, this will result in the moon reaching the Roche Limit, which will tear the moon apart, resulting either in it crashing into the planet, or creating a massive ring system around the planet, much like Saturn.
However, this isn’t to occur in a very long time. Scientists estimate that it is billions of years away. But it leads to an interesting discussion: What would Neptune look like with a large ring system?