Happy Discovery Day, Neptune!

Hey, everyone. Happy Friday. Thanks for stopping by. I hope you’re having a great day to end the week, and a great, starry weekend ahead of you.

It’s kind of a special day in astronomy, and kind of an minor holiday around here. Today, September 23, 2016 is the 170th anniversary of the discovery of what might be my favorites non-Earth planet, the planet Neptune! So with that, here’s a Friday photo!

What we have here is a photo of Neptune, the smallest and bluest of the outer giant planets. It was taken by NASA’s Voyager 2 spacecraft as it flew through the Neptune system in August 1989. It’s a great story…

Oh, wait, I forgot the photo.

Neptune, as seen by Voyager 2 in August 1989

Neptune’s discovery is a great story. After Uranus was discovered, astronomers started to notice that it wasn’t where they thought it should be. Its orbit didn’t line up with what they expected based on what was taught by Johannes Kepler and Isaac Newton. Rather than shrug, and say “Eh… ah well, what can you do?” like I would have, a bunch of incredibly smart people started figuring out what went wrong.

Of these smart people, was a French mathematician and astronomer named Urbain Le Verrier. He figured out there was another planet out there whose gravity was tugging just enough to change Uranus’s orbit. Using just math, what he saw of Uranus, and, one can assume, a pen, he figured out where the other planet should be.

As it turns out, at about the same time, another smart guy, British astronomer and mathematician, John Couch Adams came up with the same prediction as Le Verrier’s. Then, on the night of September 23-24, 1846, Johann Gottfried Galle spotted the gigantic ball of icy gas only about a degree—the width of a finger at arm’s length—from where Le Verrier’s prediction said would be.

Neptune became the first planet to be discovered without being seen; discovered only by math and brain power.

I really love this story. It’s at least part of the reason I love Neptune. Those real “if you put your mind to it…” kind of stories are incredibly inspiring.

Think of it, there were six planets. Then, William Herschel, having just discovered Uranus, could show it to people in his telescope. They had no idea there was more. For all they knew, there was a big glass wall there, just past Uranus. That was the end of the solar system. With telescopes only as sort of a secondary tool, that wall got pushed back a billion miles. Since then, the end of the solar system keeps getting pushed back again and again, with the Voyagers are leading the way.

If they could discover an entire planet without seeing it, what else can people do? As I say so often around here, wow.

Have a great weekend, and if you’re out and about tonight, clear skies!

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One thought on “Happy Discovery Day, Neptune!

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