Yes, this is a week late, but uh… better late than never and all that.
Happy “first” birthday, Neptune!
Our solar system’s last “real” planet (I’m still torn about Pluto) was discovered on September 23, 1846. Neptune is far too dim to be observed with the naked eye, so it wasn’t until the telescope was invented that it could even be seen. However, although it was observed by astronomer after astronomer, every last one of them thought Neptune to be a star (with “them” including Galileo, Jérôme Lalande and John Herschel). In 1781, British astronomer William Herschel discovered Uranus, and by 1846 it was clear that Uranus had some orbital oddities that could only be explained by the presence of another planet. Thus, Neptune is the only planet in our solar system discovered by mathematical means, not observation. Interestingly, Neptune’s massive moon, Triton, was discovered by English astronomer William Lassell just 17 days later.
Neptune is the forth largest planet by diameter and the third most dense in the solar system. It orbits the Sun at an average distance of 30.1 AU (astronomical units, the average distance from the earth to the Sun). It takes Neptune 165 years to circle the Sun, thus, if there were people on Neptune, they’d be celebrating the first year anniversary of when earthlings discovered their home.
Here’s a cool video from the BBC’s 1999 series The Planets about Neptune:
Even cooler, here’s a sound recording from the Voyager mission. This isn’t what the planet actually sounds like to human ears; it’s what the radio waves coming from Neptune sound like. And it’s really cool:
I love Neptune! It’s my favorite planet after earth!