Astro Bob: New closeups of volcano-rich Io; Jupiter’s moons do do-si-dos – Duluth News Tribune

I’ve but to see a volcano up shut, however I’ve checked out Jupiter’s moon Io many occasions by means of my telescope.

Solely a bit of bigger than our personal moon, Io is likely one of the most seismically lively our bodies within the photo voltaic system with as much as 400 lively volcanoes. Latest photographs from NASA’s

Juno spacecraft

have supplied probably the most detailed view of this tumultuous world because the Galileo satellite tv for pc orbited the Jovian system from 1995 to 2003. Come this December and once more in January 2024 Juno will swoop by for a fair nearer look.

Jupiter moons

Jupiter has 95 recognized moons, however solely 4 are seen in newbie telescopes. Galileo was the primary to see them, so that they’re referred to as the Galilean moons.

Contributed / Stellarium

None of Io’s volcanoes are seen in newbie telescopes. On the present distance of 371 million miles (597 million km) it and the opposite brilliant Galilean moons — Callisto, Ganymede and Europa — look precisely like stars lined up on both facet of Jupiter when considered by means of a small telescope. However whereas the others shine white, Io glows orange. That shade derives from sulfurous gases belched out by volcanoes which freeze on the floor and paint the moon tomato crimson, pumpkin orange and goldenrod yellow.


Earth’s inside is sizzling from gravitational contraction — the planet continues to crush itself right into a ball since its start greater than 4.5 billion years in the past — and warmth launched from the decay of radioactive components. Rock melted by the warmth turns into magma that reaches the floor by means of convection (like boiling water effervescent in a pot) and spawns volcanoes and earthquakes. Io’s warmth comes from a distinct supply.

Io is the innermost of the Galilean moons. Gravitational interactions with neighboring Europa and Ganymede have stretched the moon’s orbit in order that one finish is comparatively close to Jupiter and the opposite farther away. Astronomers say its orbit is eccentric.

The distinction in Jupiter’s pull between the closest and farthest factors of that orbit flexes the moon first a technique after which the opposite. Friction from the back-and-forth heats and melts its inside. Should you unwind a paperclip and bend the wire backwards and forwards it is going to warmth up and ultimately break. Jupiter flexes Io in the same approach.

Io volcanoes

All the intense dots are both volcanoes or different sizzling spots on the floor of Jupiter’s moon Io. The left facet of Io is in daylight; the proper facet is in darkness. Juno’s Jovian Infrared Mapper imager (JIRAM) imaged the moon in infrared gentle (which exhibits warmth as brilliant areas) throughout a July 2022 flyby.

Contributed / NASA, JPL-Caltech, SwRI, ASI, INAF, JIRAM

Temperatures contained in the moon can attain greater than 2,000 levels Fahrenheit (1,200 levels C), sizzling sufficient to soften the core and mantle and spawn volcanoes that spew poisonous fuel and sizzling magma. Lava flows composed of molten silicates and sulfur flood the floor for miles. Photos from the New Horizons spacecraft, which flew by Jupiter a number of years after NASA’s Galileo mission, recorded a brand-new giant volcano that sprouted in the course of the interim. What a busy and fearsome place!

Io eruption

This pair of photographs taken by NASA’s Galileo spacecraft captures a dynamic eruption at Tvashtar Catena, a sequence of volcanic bowls on Jupiter’s moon Io. The picture on the left is a composite from 1999 and the one on the proper a single picture from early 2000. They present a change within the location of an outpouring of sizzling, sulfurous lava over a interval of only a few months.

Contributed / NASA, JPL, College of Arizona

So no. I’ve by no means seen a volcano . . . simply 400 of them squeezed right into a pinpoint of sunshine. Io orbits Jupiter each 42.5 hours so when you see it on one facet of Jupiter tonight it will likely be situated on the other facet the next night time. For each two orbits Io completes, Europa (the subsequent moon out) completes one. And for each 4 orbits Io makes, Ganymede (additional out) makes one. This neat association, referred to as an orbital resonance, outcomes from gravitational interactions between the moons and is answerable for Io’s eccentric orbit and in the end its volcanoes.

Io changes

This montage compares related sides of Io photographed by the Galileo spacecraft in October 1999 (left) and the New Horizons spacecraft on February 2007. The most important seen function is the darkish oval composed of deposits from the Pele volcano, practically 750 miles (1,200 kilometers) throughout its longest dimension. The volcano Dazhbog (arrowed) is a distinguished darkish spot within the New Horizons picture however a lot much less conspicuous within the Galileo picture. Way more apparent is a more moderen, and on the time nonetheless lively, volcanic eruption (circled), which deposited materials throughout practically 300 miles (500 kilometers).

Contributed / NASA, JHUAPL, SRI

Callisto is probably the most distant of the Galileans with an orbital interval of 16.7 days. It shifts extra slowly night time to nighttime, spending roughly one week on both facet of the planet. Watching the 4 change positions night time to nighttime is like having tickets to a endless ballet efficiency. Drop in for a look-see the subsequent time it is clear. All you want is a 20x-30x recognizing scope or a small astronomical telescope.

Jupiter moons

These panels present chosen dates and positions of Jupiter’s 4 brightest moons the way in which they appear by means of a small telescope. North is up and west to the proper. To minimize litter I assigned every moon a quantity — 1 for Io, 2 for Europa, 3 for Ganymede and 4 for Callisto. The orbital intervals for the moons are: Io (1.8 days); Europa (3.5 days); Ganymede (7.2 days) and Callisto (16.7 days).

Contributed / Stellarium with additions by Bob King

I’ve included simulations of a few of the extra fascinating groupings of Jovian moons over the subsequent couple weeks. This is a

full-sized model

of the panel above. You may assume they’d at all times align in a straight line, however their inclinations to Jupiter’s equator fluctuate barely. As effectively, Jupiter’s and Earth’s orbits will not be precisely on the identical aircraft, so we typically look a bit of above or under the moons as they orbit the planet. For these causes they break from an ideal line, making their preparations much more fascinating.

Bob King

“Astro” Bob King is a contract author and retired photographer for the Duluth Information Tribune. You possibly can attain him at nightsky55@gmail.com.

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