APOD: A Solar Prominence Eruption from SDO (2011 Mar 07)

[APOD Robot]

A Solar Prominence Eruption from SDO

Explanation: One of the most spectacular solar sights is an erupting prominence. Two weeks ago, NASA's Sun-orbiting Solar Dynamic Observatory spacecraft imaged an impressively large prominence erupting from the surface. The dramatic explosion was captured in ultraviolet light in the above time lapse video covering 90 minutes, where a new frame was taken every 24 seconds. The scale of the prominence is huge -- the entire Earth would easily fit under the flowing curtain of hot gas. A solar prominence is channeled and sometimes held above the Sun's surface by the Sun's magnetic field. A quiescent prominence typically lasts about a month, and may erupt in a Coronal Mass Ejection (CME) expelling hot gas into the Solar System. The energy mechanism that creates a solar prominence is still a topic of research. As the Sun progresses toward Solar Maximum in the next few years, solar activity like eruptive prominences are expected to become more common.

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[bystander]

SDO Pick of the Week: Monster Prominence (2011 Feb 25)
viewtopic.php?p=143984#p143984

[neufer]

A Solar Prominence Eruption from SDO

The scale of the prominence is huge -- the entire Earth would easily fit under the flowing curtain of hot gas.

The video is awesome and the prominence is huge... but we all know that the earth is a tiny insignificant little marble.

I remember my dad taking me downtown to the Smithsonian in the mid 50's once to see black & white movies of prominences erupting. It was pretty neat back then.

[NoelC]

I always get my gas and plasma mixed up... Do they behave the same at this scale?

That thing is HUGE! Given that it was a significant size as compared to the size of the solar disk, and just about as bright, would we have felt the sunlight being particularly bright/hot during that eruption, if we had been outside under a clear sky? Would we have gotten a sunburn significantly faster in that hour and a half period?

we all know that the earth is a tiny insignificant little marble.

Graphically...

-Noel

[row]

does an increase in solar activity translate into a greater amount of solar energy hitting earth?

[Chris Peterson]

does an increase in solar activity translate into a greater amount of solar energy hitting earth?

When the Sun is at its greatest level of activity (solar maximum) it outputs about 0.1% more total energy than it does when it is at its lowest level of activity (solar minimum). This difference is related to the overall behavior of the Sun, and not individual events like this eruption. Any transient change in energy output during this eruption was too small to be detected. As impressive as events like this appear, they represent an insignificant amount of energy compared with the total energy output of the Sun.

[Chris Peterson]

I always get my gas and plasma mixed up... Do they behave the same at this scale?

Plasma is gas- gas with a significant amount of free charged particles. The behavior isn't a matter of scale- plasma behaves differently than neutral gas if there are electrical or magnetic fields present. With these solar eruptions we are seeing plasma acting under the influence of the Sun's magnetic field.

That thing is HUGE! Given that it was a significant size as compared to the size of the solar disk, and just about as bright, would we have felt the sunlight being particularly bright/hot during that eruption, if we had been outside under a clear sky? Would we have gotten a sunburn significantly faster in that hour and a half period?

The eruption is of very tenuous gas. Its energy is insignificant compared with that of the Sun as a whole. The change in total energy output during this event was probably not measurable- at least, not from the surface of the Earth.

[orin stepanek]

The videos were awesome! It's hard to imagine that the sun will burn for 5 billion more years as much material as it is expelling.

[neufer]

does an increase in solar activity translate into a greater amount of solar energy hitting earth?

When the Sun is at its greatest level of activity (solar maximum) it outputs about 0.1% more total energy than it does when it is at its lowest level of activity (solar minimum). This difference is related to the overall behavior of the Sun, and not individual events like this eruption. Any transient change in energy output during this eruption was too small to be detected. As impressive as events like this appear, they represent an insignificant amount of energy compared with the total energy output of the Sun.

When the Sun is at its greatest level of activity (solar maximum) it outputs about 10% more ULTRAVIOLET energy than it does when it is at its lowest level of activity (solar minimum). This causes the Earth's Stratopause to be about 10K warmer than normal which, in turn, makes the Stratosphere somewhat less stable dynamically.

[neufer]

The videos were awesome! It's hard to imagine that the sun will burn for 5 billion more years as much material as it is expelling.

Most of that material can be seen to be falling back into the sun in an equally awesome fashion.

[Chris Peterson]

When the Sun is at its greatest level of activity (solar maximum) it outputs about 10% more ULTRAVIOLET energy than it does when it is at its lowest level of activity (solar minimum). This causes the Earth's Stratopause to be about 10K warmer than normal which, in turn, makes the Stratosphere somewhat less stable dynamically.

You need to be a bit careful with comments like this, because there is a real potential for confusion. The solar variation in UV is highly dependent on wavelength. Between 200 and 300 nanometers, the variation is 1-2%; this spectral range accounts for about 1% of the Sun's total output. Below 200nm, the variation gets much larger, reaching as much as 50% in the extreme UV. However, these regions account for an even smaller percentage of the Sun's energy output.

As you note, the variations in UV output do affect the upper atmosphere, but it is important to recognize that they are not significant when considering the variation in total solar irradiance- that is, when considering just total energy output.

[NoelC]

Well, I'm seeing plainly, in this video reportedly shot in UV light, that the VERY large prominence is equally bright as the sun. You say it's tenuous gas, Chris, but that doesn't change the observation that it's brilliant. Some parts of it are even a lot brighter than the photosphere overall.

Just as a guess, though we can't see it all I'd say the size of this flare is at least 10% of the apparent size of the solar disk at some points. If Neufer's figures are an overall average measurement, then in an instantaneous fashion - i.e., over the 90 minute period of this particular huge flare - it seems to me one could expect to get a sunburn noticeably faster.

I don't see numbers of this size as negligible. Did I make a mistake somewhere here?

-Noel

[Chris Peterson]

Well, I'm seeing plainly, in this video reportedly shot in UV light, that the VERY large prominence is equally bright as the sun. You say it's tenuous gas, Chris, but that doesn't change the observation that it's brilliant. Some parts of it are even a lot brighter than the photosphere overall.

Just as a guess, though we can't see it all I'd say the size of this flare is at least 10% of the apparent size of the solar disk at some points. If Neufer's figures are an overall average measurement, then in an instantaneous fashion - i.e., over the 90 minute period of this particular huge flare - it seems to me one could expect to get a sunburn noticeably faster.

I don't see numbers of this size as negligible. Did I make a mistake somewhere here?

This is an extreme UV image: recorded with the AIA camera at 30.4 nm. That's a strong HeII emission line, but the energy output of the Sun in this band is on the order of a few ten-thousandths of its total energy output. So seeing this flare against the background energy is probably impossible with our measurement technology- we only see it here because we boost the contrast by blocking almost all the other energy. It's the same reason you can see prominences in narrow H-alpha, but not in white light; they simply don't have enough energy to be seen against the total solar output.

And of course, when it comes to sunburns, absolutely none of this 30 nm extreme UV makes it to the surface of the Earth.

[NoelC]

Ah, oversimplifying the term "UV" was my mistake then. Thanks for that.

-Noel

[Beyond]

Ah, oversimplifying the term "UV" was my mistake then. Thanks for that.

-Noel

At least you didn't get 'burned' for your missteak

[APOD_admirer]

Greetings all,

A newbie question:

In the last few seconds of the video, the some of the ejecta appears to flow in reverse, back towards where it came from. I found this fascinating.

Does anyone know why the flow moves in that way ? I'd be most grateful for any info.

Thanks very much,
APOD_admirer

[bystander]

In the last few seconds of the video, the some of the ejecta appears to flow in reverse, back towards where it came from. I found this fascinating.

Does anyone know why the flow moves in that way ? I'd be most grateful for any info.

Plasma rain
SDO Observes Massive Eruption, Scorching Rain

[APOD_admirer]

Click on image to enlarge

bystander, thank you for the link on "plasma rain" ! Very interesting !

Please have a look at the image with this post. It's from about the 13sec mark in the Youtube video. I've enclosed the area of interest in an ellipse. Maybe my eyes are playing tricks on me, but the flow looks like it's backtracking... watch from about 10sec to the end.

Honestly, thinking a little further, I wonder if the flow "appears" to reverse due to some sort of cooling upon expansion. But, what do I know...

Thanks again !

APOD_admirer

[BMAONE23]

As a Guess,
These solar prominences form on, follow and flow along magnetic lines. Some inherent property within them is evidently ruled by magnetism. I would think that as the force of the eruption lessens, the force of gravity gets stronger than the repulsive force behind the prominence and the material is pulled back to the surface, but because they are directed along the magnetic paths they follow, they backtrack along the magnetic field line instead of just falling straight down.

[Chris Peterson]

As a Guess,
These solar prominences form on, follow and flow along magnetic lines. Some inherent property within them is evidently ruled by magnetism. I would think that as the force of the eruption lessens, the force of gravity gets stronger than the repulsive force behind the prominence and the material is pulled back to the surface, but because they are directed along the magnetic paths they follow, they backtrack along the magnetic field line instead of just falling straight down.

Also, consider that we are seeing a 3D structure in 2D projection. We can't easily tell the difference between material reversing and following the same path back, and material coming over the top of an arched loop and traveling back down the other side, where the arch is being seen edge-on.

[APOD_admirer]

To bystander, BMAONE, and Chris,

thank you for the ideas, especially the info on magnetism and what can happen when a 3D structure is projected on 2D.

APOD_admirer

[laura_abc]

omg... the plasma rain video is fantastic! do you have more?

[Rauf]

Is there no way to watch this video or similar deleted videos again?