<< Chapter < Page Chapter >> Page >

The Galileo data show that most of the volcanism on Io consists of hot silicate lava, like the volcanoes on Earth. Sometimes the hot lava encounters frozen deposits of sulfur and sulfur dioxide. When these icy deposits are suddenly heated, the result is great eruptive plumes far larger than any ejected from terrestrial volcanoes. As the rising plumes cool, the sulfur and sulfur dioxide recondense as solid particles that fall back to the surface in colorful “snowfalls” that extend as much as a thousand kilometers from the vent. Major new surface features were even seen to appear between Galileo orbits, as shown in [link] .

Volcanic changes on io.

A series of three images that show color change due to volcanic eruption on Io. The left most image is dated “April 1997”, the center image “September 1997”, and the third image “July 1999”.
These three images were taken of the same 1700-kilometer-square region of Io in April 1997, September 1997, and July 1999. The dark volcanic center called Pillan Patera experienced a huge eruption, producing a dark deposit some 400 kilometers across (seen as the grey area in the upper center of the middle image). In the right image, however, some of the new dark deposit is already being covered by reddish material from the volcano Pele. Also, a small unnamed volcano to the right of Pillan has erupted since 1997, and some of its dark deposit and a yellow ring around it are visible on the right image (to the right of the grey spot). The color range is exaggerated in these images. (credit: modification of work by NASA/JPL/University of Arizona)

As the Galileo mission drew to a close, controllers were willing to take risks in getting close to Io. Approaching this moon is a dangerous maneuver because the belts of atomic particles trapped in Jupiter’s magnetic environment are at their most intense near Io’s orbit. Indeed, in its very first pass by Io, the spacecraft absorbed damaging radiation beyond its design levels. To keep the system working at all, controllers had to modify or disable various fault-protection software routines in the onboard computers. In spite of these difficulties, the spacecraft achieved four successful Io flybys, obtaining photos and spectra of the surface with unprecedented resolution.

Maps of Io reveal more than 100 recently active volcanoes. Huge flows spread out from many of these vents, covering about 25% of the moon’s total surface with still-warm lava. From these measurements, it seems clear that the bright surface colors that first attracted attention to Io are the result of a thin veneer of sulfur compounds. The underlying volcanism is driven by eruptions of molten silicates, just like on Earth ( [link] ).

Lava fountains on io.

An image of lava fountains on Io, with hot lava erupting below ground.
Galileo captured a number of eruptions along the chain of huge volcanic calderas (or pits) on Io called Tvashtar Catena in this false-color image combining infrared and visible light. The bright orange-yellow areas at left are places where fresh, hot lava is erupting from below ground. (credit: modification of work by NASA/JPL)

Tidal heating

How can Io remain volcanically active in spite of its small size? The answer, as we hinted earlier, lies in the effect of gravity, through tidal heating    . Io is about the same distance from Jupiter as our Moon is from Earth. Yet Jupiter is more than 300 times more massive than Earth, causing forces that pull Io into an elongated shape, with a several-kilometer-high bulge extending toward Jupiter.

If Io always kept exactly the same face turned toward Jupiter, this bulge would not generate heat. However, Io’s orbit is not exactly circular due to gravitational perturbations (tugs) from Europa and Ganymede. In its slightly eccentric orbit, Io twists back and forth with respect to Jupiter, at the same time moving nearer and farther from the planet on each revolution. The twisting and flexing heat Io, much as repeated flexing of a wire coat hanger heats the wire.

After billions of years, this constant flexing and heating have taken their toll on Io, driving away water and carbon dioxide and other gases, so that now sulfur and sulfur compounds are the most volatile materials remaining. Its interior is entirely melted, and the crust itself is constantly recycled by volcanic activity.

In moving inward toward Jupiter from Callisto to Io, we have encountered more and more evidence of geological activity and internal heating, culminating in the violent volcanism on Io. Three of these surfaces are compared in [link] . Just as the character of the planets in our solar system depends in large measure on their distance from the Sun (and on the amount of heat they receive), so it appears that distance from a giant planet like Jupiter can play a large role in the composition and evolution of its moons (at least partly due to differences in internal heating of each moon by Jupiter’s unrelenting tidal forces).

Three icy moons.

A series of three separate close-up images of icy moons. The leftmost image is labeled “Europa”, the middle image “Ganymede”, and the rightmost image “Callisto”.
These Galileo images compare the surfaces of Europa , Ganymede , and Callisto at the same resolution. Note that the number of craters (and thus the age of the surface we see) increases as we go from Europa to Ganymede to Callisto. The Europa image is one of those where the system of cracks and ridges resembles a freeway system. (credit: modification of work by NASA/JPL/DLR)

Key concepts and summary

Jupiter’s largest moons are Ganymede and Callisto, both low-density objects that are composed of more than half water ice. Callisto has an ancient cratered surface, while Ganymede shows evidence of extensive tectonic and volcanic activity, persisting until perhaps a billion years ago. Io and Europa are denser and smaller, each about the size of our Moon. Io is the most volcanically active object in the solar system. Various lines of evidence indicate that Europa has a global ocean of liquid water under a thick ice crust. Many scientists think that Europa may offer the most favorable environment in the solar system to search for life.

Questions & Answers

is their life on mars
Darius Reply
what is the origin of the universe
Ummisalmah Reply
Big Bang
Michele
what is it first cause
Ummisalmah
is its existence necessary
Ummisalmah
from where the first energy came during big bang?
Bysali
the steady state theory may be true too
Shaunak
Did there is any life probability on titan (largest moon of saturn)
sanjay Reply
Yes, there could be a possibility of existance of life because Titan is full icy mountains which are one form of water and. could assist in microbial growth
Astronomy
although life is not yet detected on it, it is theorized that when the sun starts its red giant phase, the temperatures on titan,enceladus,etc will become suitable for life and they may develop an atmosphere too
Shaunak
What is 5 dimension
Sourav Reply
hi
Danbirnianz
yo!!!
Bennett
5 dimension is truth
Bennett
form - order - structure - society - TRUTH
Bennett
nice topic! i reread this.
TPonder
why not string theory called a theory of everything
Harsh Reply
Perhaps because string theory is useless when discussing "things" like music theory, or morality and justice. Therefore cannot be a theory of "everything."
Bennett
why the energy cost
MASTER Reply
what is sagittarius
Noorzad Reply
what is gimine
Noorzad
Black hole of Milky way galaxy
deepanshu
thanks a lot for your sympath and information
Noorzad
thanks a lot for your sympath and information Deepanshu
Noorzad
Hello: My friends, How do you do?
zin
(Sagittarius A) is a name of black hole ,present center of Milky Way
Harsh
this question is for atheists what created humans , how did they evolve
ilyes Reply
not entirely sure what this question has to do with Atheism but, firstly, there is no "who", life evolved in multiple paths, humans are simply one of those paths. The process of how life evolves is a very complicated but very well researched field of biology, so it would be worth doing research...
ben
...into that field, evolution isnt disputed. However, the direct path from the common ancestor (that we share with chimps) has not yet been completed. But know for sure that humans didn't just magically appear one day, it was over millions of years of evolution
ben
(I must ask though, what has this got to do with Atheism?)
ben
idk i thought believers will say god created us
ilyes
there are many types of believers one say that god created consciousness, one say we just magically appeared out of nowhere, and one say universe was created by God(all based on people I have met so far)
Tanmay
Hey
Asim
Tanmay!
Asim
Hello
Asim
hello Asim
Tanmay
hi my friends asim and tqnmay we hhave lern okay
Eyiba
did u forget me!!
Amit
Could God have created evolution? Nope, no way, too complicated.
Bennett
yes god can do that in theory
Tanmay
@Eyiba hello
Tanmay
@Amit seems like that XD
Tanmay
haha🤣🤣
Amit
This question is for theists, what created God?
Anthony
hi
UFOLIENS
God was begotten, not made. More of a concept than an entity.
Bennett
hello
Stuart
Hi🙂🙂
Harsh
Hi🙂🙂
Harsh
Hi🙂🙂
Harsh
Hi🙂🙂
Harsh
we came by God not real old stinky water
Bryant
Here people don't have a goal to become astronomers ,rather they want to become astrologers,with this mindset,there won't be any progress in this void earth as Feynman says in his book "if I could explain it to the average person (like how astrologers do) I wouldn't have been worth the nobel price".
Akshar
God did not create the universe.. Humans created god, possibly to fill in an unwanted reality no1 wants to believe because life can be a struggle for most.
Collins
astronomy and astrology diverged from the same concept, to deny either one is to deny them both.
Bennett
may i ask a question
Raluca Reply
yes why not you don't need to ask anyone for permission
Tanmay
sure, why not?
ca
-Why there are moons in every planet but there's note in mercure ?
Amal Reply
Well with mercury Venus also does not have moon.The reason that Mercury is not having moons is since it is too close to sun and thus if it would have any moon orbiting it ,then the moon will eventually attracted by sun due to it's high gravitational force whereas mercury has the lowest gravity
Anjali
The gravitational force of mercury is lowest in solar system and it won't be able to hold a moon in it's orbit
Anjali
Nice explanation
Asim
Thank you brother
Anjali
Did general theory of relativity leads us to singularity?
Asim
yes the general theory of relativity leads us to singularity
Anjali
But Einstein was not a believer of big bang. And singularity lead us to big bang?
Asim
yes Einstein was really astonished by his mathmatical answers that came fron his equations (this is what almost every one says)
Tanmay
and there are many theories stating how our universe came in which one is big bang
Tanmay
Einstein was against the fact that anything can come from nothing that our big bang says and he also thought that singularity (infinite mass in zero volume) can not be real(also what most people say)
Tanmay
also what most people say means that there is no evidence that he was against all these things
Tanmay
Okay
Asim
Tanmay
Asim
anything else
Tanmay
Do you believe that grand unified theory can be complete in future?
Asim
Do you believe that grand unified theory will be complete in future?
Asim
yes I do believe in it as I also believe big bang
Tanmay
Well i don't believe in big bang like Einstein didn't.
Asim
do you believe in wormholes are real?
Amit
@Asim then what do you think our universe came from or how it started
Tanmay
Well it's a myth.
Asim
@Amit I believe wormholes are real
Tanmay
It came from nothing Tanmay.
Asim
Even I believe in wormholes
Anjali
So Tanmay you must believe in baby universes.?
Asim
I believe that they are many things we can't explain or give prove but they are theories,imaginations and they are the basics for new discoveries
Anjali
So ,it is useless to argue over them
Anjali
But we should try to find new possibilities if we don't believe in old ones
Anjali
you are right @anjali
Amit
what is dark matter?
Amit
can a star turn into planet?
Amit
I have doubt on how Stephen hawking posses ideas of black hole by himself?
Enceladus
why do people believe in God and how are humans made
ilyes
No amit star can't turn into planet.
Asim
you are wrong asim
Amit
also Asim, please tell me why you think the big bang is a myth?
ben
@Asim what do you mean by it came from nothing what came from nothing
Tanmay
@Asik I don't know what baby universe is if you mean early universe then the question doesn't make sense
Tanmay
@Amit starts can become cold enough for us to live at high altitude but their surface will still be made of plasma
Tanmay
@Amit dark matter is a type of substance that doesn't interact with normal matter and also gives galaxies enough mass to hold its stars rather than to fly out by its rotation
Tanmay
Sorry Asim for wrong spelling of your name
Tanmay
@Tanmay thanks for your explanation
Amit
@Tanmay but a star can turn into a planet, but this transformation only happens for a very particular type of star known as a brown dwarf.
Amit
oh, somebody has google 😂
ben
I will check and then I will tell you if it's true or not thanks for the question
Tanmay
I will check as it is really wierd but thanks for your question
Tanmay
(oh no I was joking hahaha, Amit just took the definition that you see first on google and pasted)
ben
Tanmay baby universes is when something fell in black hole it's went into another universe called baby universe according to Stephen hawking. Well i don't know weather to believe it or not.
Asim
Amit brown dwarf are not planet or stars they have their own classification these are basically failed star, not massive enough to power hydrogen fission reaction.
Asim
ahh, didn't he use that to explain where "information" goes? because recently a paper was published stating that information may actually be re-emitted by the black hole as 'encoded' hawking radiation
ben
(so it may not be going to another universe, but instead coming back into our own)
ben
Hawking radiation are basically the the radiation emitted by black hole boundaries called event horizon.
Asim
@ben someone asked me this question today so i asked here and also google it..
Amit
So re-emitting doesn't make scene.
Asim
every black hole contains a singularity?
Amit
Yep absolutely.
Asim
ohhh, no worries dude, and yeah hawking radiation is a consequence of both quantum mechanics and relativity, really cool. And look it up Asim, it's a really interesting read
ben
but a singularity is a point in space where there is a mass with a infinte density. the problem is that infinities never exist in real world.
Amit
Ben it's really difficult to relate quantum mechanics to relativity.
Asim
Dude if you have done nobel price is waiting for you. (haha)
Asim
consequence of both quantum mechanics and relativity.!!!
Amit
Amit read theory of relativity and black hole singularities in Google. Everything will be cleared.
Asim
🤣🤣🤣
Amit
ok i will read this
Amit
hahahahaha, yeah that's true I'm being lazy as hell there haha, I mean more it's something relates the big and small (it's cool to see quantum phenomena having a direct effect on something predicted by relativity)
ben
(if a GUT is found I genuinely doubt I'd be able to comprehend the maths hahaha, maybe a long a way down the road but not yet)
ben
ben you are nominated for nobel as well as oscar for your thoughts..(hahaha)
Amit
what's you thinks about gravitational waves gentlemen?
Amit
hahahaha, and I love what I know so far but honestly dude, I've learnt essentially nothing about gravitational waves at university yet, I'm hoping that's going to be next year
ben
I would love to ask someone what the effects of constructive ans destructive interference of gravitational waves would be. Would total destructive interference lead to black holes?
ben
good luck for your next year... ben
Amit
if such things happen that's gonna be amazing.....
Amit
eyy thank you dude, likewise man, wish you all the best for your endeavours
ben
eyy cheers dude, likewise for you man, wishing all the best for you
ben
thanks buddy..
Amit
💝❤
Amit
(my bad, sometimes my phone wont show the first message as being sent, so I send another just in case)
ben
Gravitational Waves could help us travel faster in the space, if we are to set on an adventure like the one in The Interstellar, lol. Just saying
Awesh
what do u think created the universe
ilyes
m curious
ilyes
I believe in the theory where it states that our universe came from death of another universe and after our universe's death another universe will come from it
Tanmay
@Amit if that's what baby universe is then
Tanmay
my current understanding of universe and black holes, I would have to disbelief it
Tanmay
@Asim @Amit there is a feild in physics where we study about the physics of those objects who have intermediate size and follow some rules of quantum physics and relativity
Tanmay
@Ben what is full form of GUT?
Tanmay
@Ben I have never seen anyone spotting interference with gravitational waves but most of the people think that it will just be like interference in waves like light or sound. Do that means it's amplitude will change and will not create and black holes or stuff
Tanmay
@Awesh yes many people in youtube(some have good degrees and are astrophysicist) say that warping space is possible using gravitational waves
Tanmay
Do you all believe in multiverse
Anjali
I believe in multiverse
Tanmay
The relation between quantum physics and relativity is like sky and the land (hahaha)
Amit
what about the air between sky(let's assume height of clouds is sky) and land. It basically means that there is a field like that you should google it up
Tanmay
it's the most mysterious field and we almost know nothing about it. there are no laws(like Newton's law of motion) or something like that
Tanmay
The most undifined and fascinating theory is string theory what do u think about it?
Amit
how can I learned quantum mechanics
Harsh
what is the model about the earth being the center of the universe called?
Lordgy Reply
geocentric model
SCIENCE
I hope you got your answer.
SCIENCE
heliocentric universe
Jason
you are wrong Jason skerbinc
SCIENCE
in heliocentric model sun is at the center of the universe
Tanmay
what is black hole and stellar black hole
azeb Reply
does Millikan consider electron axial spin in his discovery of electrons mass using q/m ratio ? If No how it is possible that he found rest mass of electron (9×10^31 Kg) ?
Anurag Reply
how did light from up
Sourav Reply
Before there stars , there was matter and radiation . Before there were neutral atoms ,there was an ionized plasma ,and when that plasma froms neutral atoms , those allow the Universe to deliver the earliest light we see today .......
Apsara
how to know the distance of a star
Sourav Reply
What is time
Sourav
Technical Infinite Measurement of Evolution
Doc
not by the book but the simplicity of word play ....
Doc
to calculate the distance of a star we use parallax method (as far as my school has taught me).
Tanmay
in this method we see the star from one point and then after traveling some distance perpendicular to the distance of star we see it again. With this we can make a triangle and then it's median will give our distance
Tanmay
And time is just a way of defining when an event happened
Tanmay
oh and we will know the distance of all the 3 sides of triangle formed above if we multiply the time taken by light with speed of light and the third side will be known to us as it is dependent on our will
Tanmay
what is space fabric
Harsh
parallex method
Harsh
what is spacetime velocity?
Amit
Hi i am Gurashish
Gurashish
hello
Samuel
Hi
Gurashish
perhaps we calculate the time that light take from planet Earth to the star in question! the speed of light is 300000 km in a second! we Have to do a calculated! I hope it is right! it is very complicated!
Michele
Parallax method
Awesh
Practice Key Terms 1

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Astronomy. OpenStax CNX. Apr 12, 2017 Download for free at http://cnx.org/content/col11992/1.13
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Astronomy' conversation and receive update notifications?

Ask