Eruption of the Tvashtar volcano on Io, as viewed from the New Horizons spacecraft during its Jupiter flyby (March 2007)

During this time, a 25-kilometre (16 mi) long, 1-to-2-kilometre (0.62 to 1.24 mi) high curtain of lava was seen to erupt from one patera, a lake of superheated silicate lava erupted in the largest patera, and finally a plume of gas burst out, rising 385 kilometres (239 mi) above Io and blanketing areas as far away as 700 kilometres (430 mi).[2]

An eruption on Tvashtar on February 26, 2007 was photographed by the New Horizons probe as it went past Jupiter en route to Pluto. The probe observed an enormous 330-kilometre (210 mi) high plume from the volcano, with an as-yet unexplained filamentary structure made clearly visible by the background light from the sun.[3]

https://en.wikipedia.org/wiki/Tvashtar_Paterae

Damn, I'm trying to imagine a mile-high curtain of lava.

Volcanic plumes(not necessarily Tvashtar) were imaged^source by Voyager 1 in 1979 and by Galileo^source in 1997 as well, so I think it's pretty fair to say they happen "often"^TM

The fact that several eruptions appear to be occurring at the same time suggests that Io has the most active surface in the solar system and that volcanism is going on there essentially continuously.

The Prometheus plume can be seen in every Galileo image with the appropriate geometry, as well as every such Voyager image acquired in 1979. It is possible that this plume has been continuously active for more than 18 years.

Io is the most geologically active body in the solar system. It has constant volcanic activity.

Yes, the cloud is big. We get it, you vape

Thank you. I used it to colorize the gif

http://i.imgur.com/TAUkMfc.gifv

Is there an explanation for why the lava appears blue, as opposed to the usual orange-red we get on Earth?

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Not Tvashtar, but another plume imaged by Voyager 1:

Another characteristic of the observed volcanism is that it appears to be extremely explosive, with velocities more than 2,000 miles an hour (at least 1 kilometer per second). That is more violent than terrestrial volcanoes like Etna, Vesuvius or Krakatoa.

Edit:

Here is a calculation of speeds of the plume of Tvashtar from New Horizons^source showing 0.7km/second.

Standing there would've been amazing!

So is standing right next to a nuclear bomb going off.

I'm just imagining at one point humans harnessing that energy, 2254 is going to be an exciting time in history.

Oh dang I need to take a page from your book... all I can think of is how unfair it is to never see this with my own eyes, and also why can't we hurry some high-def cameras into space!

Cryovolcanism can happen on bodies with subsurface liquid and otherwise solid cores.

The fact is that Io would propably have a solid core if things were different.

In this case, the different gravitational attraction of Jupiter on differents parts of Io (because some are regions closer to the Jupiter than others) ends up "squeezing" the satellite and heating it up due to inner friction forces. This heat builds up, melting some parts of its core and creating those curious volcanoes you just saw.

Not sure but I'm sure you could find out by searching for eruptions on celestial bodies.

Almost no mass is getting pushed out of the moon's gravity well so the moon is not getting pushed much either.

Not on Io, but Enceladus experiences thrust from volcanism. I wrote a reply here to a similar question if you're interested.

I need to know this as well. That thing should be rocketing out of the solar system right now.

The resolution on Io will not be very good. Here's a mockup I made of what Io will look like through JunoCam at the closest possible distance between Juno and Io that could ever happen. Not very good.

There's a joke in there about how tiny that image is...seriously though, do you have a link to higher res images of the same? I would love to see them!

They are named after dieties of volcanoes, fire, smithing, etc.

Yes, but almost certainly not on Io. The eruption would have to throw ash and rocks out at escape velocity or faster. If everything falls back down, no (net) momentum is exchanged. This might be a stupid analogy, but it would be like firing a gun with an elastic band attached to the bullet. The gun would recoil initially, but when the elastic band pulls the bullet back, it pulls the gun also. Unless the bullet breaks the elastic band (representing gravity here) and leaves the gun for good, there's no net thrust.

Io is small, but it still requires 2.558 km/s (5,722 mph) to escape its gravity, which is a lot. A volcano on Earth would have to eject things at 11.18 km/s (25,010 mph) to send them out into space, which is virtually impossible. Even if you could achieve those velocities on either Earth or Io, their atmospheres would stop anything from escaping. Yes, Io has an atmosphere, mostly made out of volcanic gases (sulfur dioxide).

However, Enceladus, one of Saturn's moons, is also volcanically active, and is much smaller. Its escape velocity is 0.239 km/s (535 mph), but its geysers eject streams of water at ~0.608 km/s (=2.2 km/hr or 1,360 mph). This water actually ends up becoming Saturn's E-ring, as it is not traveling fast enough to escape Saturn. The thrust would be extremely low, however. Wikipedia claims it ejects only 200 kg/s, which is a lot less mass moving much slower than exhaust from a human-built rocket. It would be about 112 kN (25,000 lbf) of thrust applied to Enceladus. The Space Shuttle Main Engines produce 500,000 lbf of thrust each. This tiny amount of thrust applied to such a large object will not alter its orbit significantly. I would estimate that Enceladus's orbit would be much more heavily affected by the other moons of Saturn.

Normally bodies as small as Enceladus and Io would have cooled off enough to have completely solid cores and no volcanic activity, but both Enceladus and Io are heated by "tidal heating." This happens in eccentric orbits. The near side of a moon is more strongly attracted to the main body (Jupiter and Saturn here) than the far side, which both deforms the whole body and makes the near side want to orbit the main body significantly faster than the far side. This effect is most prominent at periapsis (closest approach) and weakest at apoapsis (furthest point in the orbit), so the moon significantly deforms and then relaxes constantly. Deforming an object like this causes it to heat up. You can see this with a coat hanger or thick wire. Bend it back and forth really fast and then touch the joint that you bent. It will be hot.

I'm interested in an answer to this too

I'm only a college student so I'm probably wrong but I would imagine not. Even though the eruption was huge almost 0 mass left the moons gravity well.

Probably not. A simple physics equation to look at would be F=MA. The force of an event is equal to the mass times the acceleration produced. Even though Io is only a moon, it still has incredibly large mass. We think it's 9.94e+22 kg. That's an incredibly large number. For there to be any change in its orbit, any change in the acceleration, the force also needs to be a supermassive number like the mass. While I'm sure this eruption was strong, it likely isn't that strong.

I'm not qualified enough to say this, but I think no eruption would be powerful enough to propel any mass to escape velocity. Not in the case of planets or moons but check out the outgassing of asteroids.

This image came out in 2007 when New Horizons went by Jupiter. You're seeing an old image being posted here.

Lava, Io is super hot. It is so close to Jupiter that it gets really hot through tidal forces.