Words of the Week: Zone! Belt!

Hey, Sky Fans! Welcome back! Wednesday already, eh? Time moves along.

Update: I made some mistakes in what I originally wrote below, and have since corrected them. This was mostly in the parts about what the atmosphere is made up of, and how big the storms are. What’s here now is, hopefully, correct. Sorry about the mistakes.

Have you seen these photos of the planet Jupiter, the giant-and-stripey one, that have been coming in from NASA’s Juno probe? I can’t look away. Here’s one:

Jupiter’s South Pole (from Juno/NASA)

That photo was taken by Juno when it was only 32,000 miles (52,000 km) from Jupiter, near perijove, earlier this month. That’s less than a tenth of the distance from the Earth to the Moon.

Here’s another:

Jupiter, from NASA/Juno

Not bad for a probe that wasn’t even going to have a color camera when it was first designed, huh? How could you go all the way to Jupiter without a camera, though? I can’t even go all the way to the supermarket without one.

The Juno probe, which arrived at Jupiter in early July 2016, is in a highly elliptical orbit around the planet, over its poles, which takes it about 53 days to make it around once. The perijove, which you might remember from months ago when we talked about the word apsis, is the point when it, or any other object for that matter, gets to its closest point in its orbit around Jupiter. Perijove is specific to Jupiter. Perigee is the closest point around Earth, perihelion is the closest point around the Sun.

There’s been a lot of amazed swearing around my camera-and-Slinky strewn desk over the last few days, just like I have been for years over the pictures of the Saturn system from Cassini.

These are some of the most incredible photos of the solar system’s biggest planet that we’ve seen. See those round things in among the blue? Purple? Those are giant storms, 600 miles across. Some similar storms on Jupiter are as big as Earth is. Try to picture that if you can. Those storms look positively tiny against Jupiter’s south polar region, but some of them are the size of this pile of rocks we’re on now.

If you want to try to imagine the scale of the whole thing, Jupiter’s about 87,000 miles across, which is more than 10 times bigger than Earth’s 7900 miles. In three dimensions, that’s big enough that 1300 Earths would fit inside it. We have one moon, and it’s a big one, but Joops has close to 70, including four giant ones, one of which is bigger than the planet Mercury. There’s no end to the superlatives for Joops. It’s an amazing place; big, too.

Let’s take a break from the Juno plotzing, though, and, instead, switch to plotzing over this probably-iconic photo of Jupiter that Voyager 1 snapped in 1979:

Jupiter as seen by Voyager 1 in 1979

In that photo, we can see the Great Red Spot, the giant, multiple-Earth-sized storm just south of the planet’s equator, but we can also see this week’s Words of the Week!

Belts and Zones!

Voyager 1 approaching Jupiter in 1979

Jupiter is a gas planet. It’s mostly hydrogen and helium, like in the Sun, mixed with other things, but no solid surface like here on Earth. It’s just hydrogen and helium all the way through, getting denser and denser, and eventually liquefying, as it goes deeper. In fact, part of what we’re hoping to learn from Juno is whether there’s even a solid, rocky core in the middle of it all.

When we see Jupiter, we’re looking at the top of its clouds.

As I’m sure you’ve noticed before, the atmosphere is opaque, and has stripes. The different colors are caused by different amounts of other gases mixed in with the hydrogen and helium; mostly ammonia, methane and water vapor. The darker, warmer bands are falling gases called belts, and the lighter, and cooler ones are called zones, which have rising gases. This means these clouds aren’t flat as they look in books and on websites. They have depth and texture. The clouds in the cooler zones are higher up, while the warmer belts’ clouds are lower. This is just like it is here on Earth. The upper reaches of our atmosphere is colder than the part lower to the ground.

Each belt and each zone has its own official name and abbreviation. I started to draw a map, but the one I found on Wikipedia (yeah…) is better than what I was able to draw, even if you remember how liberal I am with the quality of my artwork (if you can call it that):

Jupiter cloud bands.svg
By Sakurambo at English Wikipedia – Transferred from en.wikipedia to Commons by Shizhao using CommonsHelper., Public Domain, Link
  • NPR: North Polar Region
  • NNTZ: North-North Temperate Zone
  • NNTB: North-North Temperate Belt
  • NTZ: North Temperate Zone
  • NTB: North Temperate Belt
  • NTropZ: North Tropical Zone
  • NEB: North Equatorial Belt
  • EZ: North Equatorial Zone
  • SEB: South Equatorial Belt
  • STropZ: South Tropical Zone
  • STB: South Temperate Belt
  • STZ: South Temperate Zone
  • SSTB: South-South Temperate Belt
  • SSTZ: South-South Temperate Zone
  • SPR: South Polar Region

I’ve always loved looking at photos of Jupiter. I think Saturn, thanks to all its rings and its almost completely uniform yellow color, gets more press, but for me, there’s something about Jupiter that sends me places Saturn doesn’t. It really makes my imagination move in a different way. There’s a certain unsettling, “What in the world…?” feeling I get looking at pictures of Jupiter that I don’t get looking at anything else. Put some soaring and triumphant-sounding music over it all, and I can’t stop myself.

Incidentally, Saturn has regions like Jupiter’s, but they’re difficult to see because the clouds’ coloring blends together more smoothly.

So, there you have it. The next time you see some photos or the view of Jupiter in a telescope, you’ll have a little more to talk about. I hope this helps.

Clear skies, everyone!


9 thoughts on “Words of the Week: Zone! Belt!

  1. I have been trying to draw Jupiter the last few nights. It is amazing how much you see when you really try. I’ve been dealing with a lot of what you mention here in terms of understanding the composition of the planet.

    Liked by 1 person

      1. Thanks, though I am not impressed with my Jupiter drawings. It’s been decades since and I drew and this and my Moon and (last year’s) Mars attempts convinced me I need to relearn the craft before proceeding. Still, in the interest of science, I will at some point post them. 🙂

        Liked by 1 person

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