APOD: Auroras and the Magnetosphere of Jupiter (2016 Apr 06)

[APOD Robot]

Auroras and the Magnetosphere of Jupiter

Explanation: Jupiter has auroras. Like near the Earth, the magnetic field of our Solar System's largest planet compresses when impacted by a gust of charged particles from the Sun. This magnetic compression funnels charged particles towards Jupiter's poles and down into the atmosphere. There, electrons are temporarily excited or knocked away from atmospheric gases, after which, when de-exciting or recombining with atmospheric ions, auroral light is emitted. The featured illustration portrays the magnificent magnetosphere around Jupiter in action. In the inset image released last month, the Earth-orbiting Chandra X-ray Observatory shows unexpectedly powerful X-ray light emitted by Jovian auroras, depicted in false-colored purple. That Chandra inset is superposed over an optical image taken at a different time by the Hubble Space Telescope. This aurora on Jupiter was seen in October 2011, several days after the Sun emitted a powerful Coronal Mass Ejection (CME).

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[RocketRon]

As a gas giant, what in Jupiters makeup would enable this magnetic field etc to occur ?

[Guest]

When they mention 'several days', does that mean 3 days or 10 days. And does this provide an opportunity to find a way to harness this energy to get a probe from here to there in that kind of time frame? Mixing SI and Imperial units, and thinking about solar sail technology (theory?), what would be the horse-power per cubic meter of sail?

[Nilesh Pune]

As a gas giant, what in Jupiters makeup would enable this magnetic field etc to occur ?

Jupiter has large amount of hydrogen in it, some of it gets compressed at center due to tremendous gravity & atmospheric pressure of Jupiter. the compressed hydrogen atoms get so close that they behave like metal atoms- allowing free flow of shared electrons- this phase is called metallic hydrogen.
thus core of Jupiter is electrically conducting & also it is rotating at fast speed, which creates strong magnetic field.

such strong magnetic fields are not observed on other gas giants due to absence of conducting core.

[daveboling]

Currently, exoplanets are detected through the wobble, or temporary dimming of the parent star, and perhaps in ways I have not read. Would it be possible to detect exoplanets, in systems where the orbital plane is orthogonal (or nearly so) to our direction from that system, through observation of the spectral emmissions of their auroras? Would not planets with magnetospheres be more likely of harboring, or sustaining life since the magnetosphere would block a significant portion of incoming radiation?

[heehaw]

such strong magnetic fields are not observed on other gas giants due to absence of conducting core.

Saturn does have a magnetic field, and, remarkably, it is precisely aligned with Saturn's spin (rotation) axis, the only celestial object for which such alignment occurs! Wonder why?

[sshea]

Love today's image - both artistic and scientific!
And I have to say, I have coffee with you almost every morning. As interesting as the APOD image is every day, your links often make me smile, e.g., your excitement level links today.
Thanks for all you do!

[neufer]

[b][color=#0000FF]Tilts of planetary magnetic fields with respect to their rotation axes. Credit: Fran Bagenal & Steve Bartlett[/color][/b]

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Saturn does have a magnetic field, and, remarkably, it is precisely aligned with Saturn's spin (rotation) axis, the only celestial object for which such alignment occurs! Wonder why?

Gas giant Saturn & ice giant Neptune
are quite similar in that they both:

• 1) Radiate ~255% their Solar energy
  2) Have extremely high surface winds.

However, gas giant Saturn & ice giant Neptune differ radically in their dipole tilts:

• 1) Saturn dipole tilt <0.5°
  2) Neptune dipole tilt ~47°

Is this dipole tilt difference because the strong internal heating source is mostly

• 1) Above the thin shell of electrically conducting liquids for Saturn but
  2) Below the thin shell of electrically conducting liquids for Neptune

<<Like Jupiter's magnetic field, Saturn's is created by a fluid dynamo within a layer of circulating liquid metallic hydrogen in its outer core. Saturn's magnetic dipole is strictly aligned with its rotational axis, meaning that the field, uniquely, is highly axisymmetric (i.e., dipole tilt <0.5°).

Saturn has a hot interior, reaching 11,700 °C at its core, and it radiates 2.5 times more energy into space than it receives from the Sun. Jupiter's thermal energy is generated by the Kelvin–Helmholtz mechanism of slow gravitational compression, but this alone may not be sufficient to explain heat production for Saturn, because it is less massive. An alternative or additional mechanism may be generation of heat through the "raining out" of droplets of helium deep in Saturn's interior. As the droplets descend through the lower-density hydrogen, the process releases heat by friction and leaves Saturn's outer layers depleted of helium. These descending droplets may have accumulated into a helium shell surrounding the core.>>

<<Neptune also resembles Uranus in its magnetosphere, with a magnetic field strongly tilted relative to its rotational axis at 47° and offset at least 0.55 radii, or about 13500 km from the planet's physical centre. Before Voyager 2's arrival at Neptune, it was hypothesised that Uranus's tilted magnetosphere was the result of its sideways rotation. In comparing the magnetic fields of the two planets, scientists now think the extreme orientation may be characteristic of flows in the planets' interiors. This field may be generated by convective fluid motions in a thin spherical shell of electrically conducting liquids (probably a combination of ammonia, methane and water) resulting in a dynamo action.

Neptune's more varied weather when compared to Uranus is due in part to its higher internal heating. As with Uranus, the source of this heating is unknown, but the discrepancy is larger: Uranus only radiates 1.1 times as much energy as it receives from the Sun; whereas Neptune radiates about 2.61 times as much energy as it receives from the Sun. Neptune is the farthest planet from the Sun, yet its internal energy is sufficient to drive the fastest planetary winds seen in the Solar System. Depending on the thermal properties of its interior, the heat left over from Neptune's formation may be sufficient to explain its current heat flow, though it is more difficult to simultaneously explain Uranus's lack of internal heat while preserving the apparent similarity between the two planets.>>

[Fred the Cat]

Quite the sight if we could see it that way in the night sky.

Jupiter Magnetic Field in Night Sky.jpg (8.12 KiB) Viewed 2760 times

Jupiter's space is quite dynamic.

Lots of people have put some thought into this topic.

[bystander]

http://asterisk.apod.com/viewtopic.php?t=35758

[Asterhole]

Sorry to overrule here, Art but Neptune is assuredly a GAS giant. Exactly what lies beneath the upper atmosphere layer of methane is uncertain, but it probably isn't frozen, or at least solidly so.

But onto the Jovian aurorae: At that scale, any one of the flashes could easily outsize the planet Earth, it would seem.

[geckzilla]

Sorry to overrule here, Art but Neptune is assuredly a GAS giant. Exactly what lies beneath the upper atmosphere layer of methane is uncertain, but it probably isn't frozen, or at least solidly so.

But onto the Jovian aurorae: At that scale, any one of the flashes could easily outsize the planet Earth, it would seem.

They're not called ice giants because they're made of solid ice, sheesh...
https://en.wikipedia.org/wiki/Ice_giant

[Fred the Cat]

Sorry to overrule here, Art but Neptune is assuredly a GAS giant. Exactly what lies beneath the upper atmosphere layer of methane is uncertain, but it probably isn't frozen, or at least solidly so.

But onto the Jovian aurorae: At that scale, any one of the flashes could easily outsize the planet Earth, it would seem.

They're not called ice giants because they're made of solid ice, sheesh...
https://en.wikipedia.org/wiki/Ice_giant

I think it's been found.

And the strangest thing, it's right here – in Blue Earth. He does look cold! I just hope he hasn't been eating his Brussels Sprouts although I do wish they'll call the new ninth planet - Jolly

[Boomer12k]

Awesome depiction...

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