Archive | June, 2016

Europa D.6.24

23 Jun

Europa, a little bit farther out in the system. It may have a very deep liquid ocean under its icy crust, due also to tidal heating. That tidal squeeze, release, squeeze, release is what keeps Europa warm, not as hot as Io, but warm. But also warm enough to support the idea that there may be liquid water under that icy surface.

Magnesium sulphate might be the major salt component, as opposed to Earth, where we have sodium chloride; regular table salt is what makes our oceans salty. On Europa it might be magnesium sulphate.

Elliptical orbit of Io D.6.23

22 Jun

How did Io get into an elliptical orbit? The elliptical orbit is caused by the orbital resonances with the other Galilean moons, so in particular Europa and Ganymede. And you know what an orbital resonance is. It just means that one planet goes around an integer multiple times of another planet. So in this example every time Ganymede, which is one of the farther ones out, goes around one orbit, which it completes in about seven days. So every time it does one of those, there’s an orbital resonance with Europa.

Europa will go around twice in the same amount of time, and Io will go around four times. So these are orbital resonances because they are exact integer multiples of one another. It’s not 4.2 or 3.8; it’s four because you have an integer relationship between the orbital periods. And it’s these orbital periods that give a little extra gravitational nudge, which then pushes Io into its elliptical orbit, which causes the tidal stressing from Jupiter, which causes the fantastic magma sulphur displays on Io.

Io D.6.22

21 Jun

The Galilean moons of Io, Europa, Ganymede, and Callisto are quite geologically active.

Io is the most volcanically active object in the solar system. It’s got this yellow colour and that yellow is from sulphur. There are lots of dark regions and there are red regions. And this is from volcanic plumes that come up, spew their material onto the surface. In some cases the magma erupts with such velocity that it can escape Io and then becomes part of Jupiter’s atmosphere, its magnetosphere. And so you get this very blotchy appearance from the hyperactive volcanic activity on Io. We’ve actually even been able to watch some of the volcanos erupt on Io.

We can actually watch, in real time, the surface of Io change due to its volcanism.

So, why does Io, it’s relatively small, why does it have such active volcanisms? Well, it’s primarily due to its interior being kept very hot from tidal heating from Jupiter. So Io goes around in an elliptical orbit around Jupiter, but Jupiter’s gravity is so strong that when Io is close the planet is a little bit deformed. And then as it gets farther away, it goes back into a more spherical shape.  And you know that if you take an object and you squeeze it and you squeeze it and you let it go, and you squeeze it, and you let it go, that the object heats up, right? You can do this with a ball on Earth. And the same thing happens with Io. And this constant stressing from the tidal effects of Jupiter is what keeps Io’s interior incredibly hot and sustaining that sulphur volcanism going on – on Io.

Jovian Planets Moons D.6.21

20 Jun

There are more than 100 known moons orbiting the Jovian planets. There are larger moons of those orbiting Jupiter, Saturn, Uranus, Neptune, and then the dwarf planet Pluto.

Most of the large moons around the Jovian planets probably formed from the disks of gas and dust that surrounded the Jovian planets when they were young.

There is the big disk going on with the Solar System and then each of the Jovian planets makes a little disk from which they form their moon.

A lot of the smaller moons are probably captured asteroids or comets because they don’t look very spherical; they’re irregularly shaped and very small. And so they’re probably captured comets and asteroids.

Rotation and Magnetic Planets D.6.20

20 Jun

Saturn, is very closely perfectly aligned on Saturn so both rotation and magnetic are together.

Uranus is a very odd case in that it’s tipped on its side so it goes around the solar system sideways with its rotation axis almost in the plane of its orbital. And then its magnetic axis is almost 98 degrees away from that.  So on Uranus its rotation axis and its magnetic axis are wildly different.

On Neptune it’s a little bit in between, a little bit more similar to Jupiter or Saturn. Not as extreme as Uranus, but still different than what it is on Earth. And that’s a little bit about the structure of the Jovian atmosphere with belts and zones and weather and then the magnetic fields of the Jovian planets

Earths Axis D.6.19

19 Jun

On Earth, we have the north rotation axis and then we have a magnetic field axis, which is separated by about 11 degrees.

This is why when you have a compass, it gets you north or south. It doesn’t get you to exact north, because of the offset between the magnetic axis and the rotation axis. Just for clarity, the north rotation access is actually the south magnetic access of the earth. Why, because you have the compass and the north of the compass points towards the south pole because north and south attract each other and so on Earth you want to think of it as a bar magnet.

The north pole of the Earth’s magnet is the south rotation pole of the Earth. Jupiter is similar, there’s a slight misalignment in the magnetic field axis and the rotation axis.

Jovian planets multiple cloud layers D.6.18

18 Jun

The Jovian planets have a layered interior with very high internal pressures. So their differences mainly come from the different amounts of hydrogen helium that they gathered in.

The Jovian planets all have multiple cloud layers, much like the terrestrial planets do, that give them very distinct colours. Because they’re made of different elements, it gives them fast winds and very large storms.