This is the front page of the Simple English Wikipedia. Wikipedias are places where people work together to write encyclopedias in different languages. We only use simple English words and grammar here. Simple English Wikipedia is for everyone! That includes children and adults who are learning English.
There are 254,181 articles in this Simple English Wikipedia. All of the pages are free to use. There is a discussion in the GNU Free Documentation License. You can help here! You may change these pages and make new pages about whatever you want. Read the help pages and other good pages to learn how to write pages here. If you need help, you may ask questions at Simple talk.
When writing articles here:
Use easy words and shorter sentences. This lets people who know little English read them.
Write good pages. The best encyclopedia pages have useful, well written information.
Use the pages to learn and teach. These pages can help people learn English. You can also use them to make a new Wikipedia to help other people.
Simple doesn't mean little. Writing in Simple English doesn't mean that the readers want the information simple, the words are simple. Articles don't have to be short to be simple, expand the articles, include a lot of information, but use basic vocabulary.
Neptune's mass is 17 times Earth's mass and a little bit more than Uranus' mass. Neptune is denser and smaller than Uranus. Its greater mass makes its gravity make its atmosphere smaller and denser.
It was named after the Roman god of the sea, Neptune. Neptune's astronomical symbol is ♆, the trident of the god Neptune.
Neptune's atmosphere is mostly hydrogen and helium. It also contains small amounts of methane which makes the planet appear blue. Neptune's blue color is much darker than the color of Uranus. Neptune also has the strongest winds of any planet in the Solar System, as high as 2,100 km/h or 1,300 mph.
Urbain Le Verrier and John Couch Adams were the astronomers who discovered Neptune. Neptune was not discovered using a telescope. It was the first planet to be discovered using mathematics. In 1821, astronomers saw that Uranus' orbit was different from what they expected. Another nearby planet's mass was changing Uranus' orbit. They found Neptune was the cause.
Voyager 2 visited Neptune on 25 August 1989. It was the only spacecraft to visit the planet. Neptune used to have a huge storm known as the "Great Dark Spot". Voyager 2 discovered the spot in 1989. The dark spot was not seen in 1994, but new spots were found since then. It is not known why the dark spot disappeared. Visits by other space probes have been planned.
Neptune has five rings. These rings are hard to see from the Earth.