If the sun were as tall as a typical front door, the Earth would be the size of a nickel and Neptune would be about as big as a baseball.
Neptune is the eighth planet from the sun at a distance of about 4.5 billion km (2.8 billion miles) or 30.07 AU.
One day on Neptune takes about 16 hours (the time it takes for Neptune to rotate or spin once). Neptune makes a complete orbit around the sun (a year in Neptunian time) in about 165 Earth years (60,190 Earth days).
Neptune is a sister ice giant to Uranus. Neptune is mostly made of a very thick, very hot combination of water (H2O), ammonia (NH3), and methane (CH4) over a possible heavier, approximately Earth-sized, solid core.
Neptune's atmosphere is made up mostly of hydrogen (H2), helium (He) and methane (CH4).
Neptune has 13 moons. Neptune's moons are named after various sea gods and nymphs in Greek mythology.
Neptune has six rings.
Voyager 2 is the only spacecraft to have visited Neptune.
Neptune cannot support life as we know it.
Want to go outside and view the planets without a telescope? You can, but you won't see Neptune. Neptune is the only planet not visible to the naked eye. This is due to the planet's extreme distance from the Earth.
Fact: Sometimes, during the course of Neptune's orbit, dwarf planet Pluto is actually closer to the sun, and us, than Neptune. This is
due to the unusual elliptical (egg) shape orbit of Pluto.