字幕表 動画を再生する 英語字幕をプリント Something is up with Uranus. Well, that's kind of an understatement. The seventh planet from the Sun is a real oddball in our solar system, and yet we've only explored it once, back in the 1980s. Scientists recently gave data from that mission a closer look, and discovered the ice giant was doing something unexpected. It turns out Uranus is leaking gas. Let's just address the elephant in the room: Uranus. It's unfortunate that astronomer Johann Bode chose to name it after the Greek god of the sky. I know, all the other planets are named after Roman gods. What was he thinking? But if it were up to William Herschel, who discovered the planet in 1781, we'd be calling it Georgium Sidus after King George III of England. So, Uranus it is! Since that's what I'll be calling it this whole episode, let's try and be mature about it, shall we? Anyway, Uranus is shooting gas off into space. Tons of it. Huge rips. The data from our mission to Uranus, Voyager 2, show in 1986 it ejected a mass of electrically excited gas roughly 30 times wider than Earth's diameter. Where did this gas go? Well because of the, ahem, solar wind, the gas goes where the sun don't shine. See this ejection of gas was what's known as a plasmoid. They occur when ions from the atmosphere follow magnetic field lines. These lines on the side facing the sun experience intense magnetic radiation from the solar wind, sometimes enough to break them. The field lines can then whip around to the back of the planet and reconnect. When that occurs, the ions in the pinched-off portion are sent hurtling into space. Plasmoids aren't uncommon; in fact they've been spotted around several planets. But we only just noticed this one from decades ago because of a few complicating factors. First, like I said, there isn't a lot of data, just what we have from that Voyager 2 flyby. And second, Uranus is just weird. It and Venus are the only two planets that spin on their axes from east to west, opposite of the rest of the planets in the solar system. However, unlike any other planet, Uranus is sideways. Its equator is almost perpendicular to its plane of orbit, possibly from getting smacked by an Earth-sized object. Side note, pun intended: this gives Uranus some crazy seasons, with summer on one pole consisting of about 21 straight years of daytime while the other pole experiences 21 years of continuous dark winter. On many planets that have them, magnetic fields more or less line up with their geographic poles, which is why a compass works well enough on Earth. But Uranus just can't stop being silly, and its magnetic axis is tilted at almost 60 degrees from its axis of rotation. And to make things just that much more complicated, it's also offset from the planet's center by about a third of the planet's radius. All this makes for a very odd and twisted magnetic field with some unusual properties, like it opens and closes to the solar wind daily. So finding this plasmoid hidden in Voyager 2's magnetometer data required examining it at a higher resolution than ever before. Even in such fine detail, the plasmoid showed up as just a 60-second blip, meaning it was one of those silent-but-deadly ones. (Well, I assume it'd be deadly if you tried to inhale what is probably mostly ionized hydrogen, anyway.) When you take a deep dive into Uranus, you discover it's such a strange and magical place. I didn't even talk about how it possibly rains diamonds far under its gassy surface. It's kind of surprising it was called “the most boring planet” after Voyager 2's pictures were underwhelming. The scientists who spotted this plasmoid were looking for a reason to send a probe back to Uranus. Hopefully this data and an upcoming convenient alignment of planets in the 2030s encourages us to further plumb the depths of Uranus. Another acceptable pronunciation of the planet's name is "yur-in-us." Could I have called it that this whole episode? Yes. Did I? No. We may not be going back to Uranus anytime soon, but we're very interested in Jupiter. Specifically some of its moons that may have the right conditions for life. Check out Amanda's video on that here. Make sure to subscribe to Seeker for even more planetary updates and as always, thanks for watching. I'll see you next time.