APOD: 50,000 Kilometers over the Sun (2016 Sep 19)

APOD Robot · Post by **APOD Robot** » Mon Sep 19, 2016 4:07 am

50,000 Kilometers over the Sun

Explanation: What's happening at the edge of the Sun? Although it may look like a monster is rampaging, what is pictured is actually only a monster prominence -- a sheath of thin gas held above the surface by the Sun's magnetic field. The solar event was captured just this past weekend with a small telescope, with the resulting image then inverted and false-colored. As indicated with illustrative lines, the prominence rises over 50,000 kilometers above the Sun's surface, making even our 12,700-diameter Earth seem small by comparison. Below the monster prominence is active region 12585, while light colored filaments can be seen hovering over a flowing solar carpet of fibrils. Filaments are actually prominences seen against the disk of the Sun, while similarly, fibrils are actually spicules seen against the disk. Energetic events like this are becoming less common as the Sun evolves toward a minimum in its 11-year activity cycle.

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obobo · Post by **obobo** » Mon Sep 19, 2016 4:20 am

" The solar event was captured just this past weekend with a small telescope"

It looks way to good for a small telescope. If the small telescope part is right then I suspect it more like just the prominence was used from the small telescope and it was added to some high resolution setup. ( I think I understand the invert and false color part.)

I am not telescope smart so please inform me.

Thanks.

old stupid dude · Post by **old stupid dude** » Mon Sep 19, 2016 4:37 am

Never realized the atmosphere of the Sun was so white. Is it because it is scattering all wavelengths equally?

Chris Peterson · Post by **Chris Peterson** » Mon Sep 19, 2016 5:04 am

old stupid dude wrote:Never realized the atmosphere of the Sun was so white. Is it because it is scattering all wavelengths equally? :?: :? :(

It's because the image has been inverted (you're looking at a negative). If you undo the processing, you get something close to the original image:

Chris Peterson · Post by **Chris Peterson** » Mon Sep 19, 2016 5:13 am

obobo wrote:It looks way to good for a small telescope.

The theoretical resolution for a 104mm aperture is about one arcsecond. The image scale appears to be about 0.8 arcsec/pixel, and the smallest details I can see are at least a few pixels across, so the resolution we're seeing here is consistent with this small telescope on a day of very good seeing conditions.

digitalsky · Post by **digitalsky** » Mon Sep 19, 2016 9:37 am

It looks way to good for a small telescope. If the small telescope part is right then I suspect it more like just the prominence was used from the small telescope and it was added to some high resolution setup. ( I think I understand the invert and false color part.)

I will take this as a compliment - thanks

Pete Lawrence

Joe25 · Post by **Joe25** » Mon Sep 19, 2016 3:01 pm

Gee, and what do you suppose creates/causes magnetic fields to arise ? (that are holding the prominence aloft)

Chris Peterson · Post by **Chris Peterson** » Mon Sep 19, 2016 3:41 pm

Joe25 wrote:Gee, and what do you suppose creates/causes magnetic fields to arise ? (that are holding the prominence aloft)

The star is made up of plasma- a fluid form of matter consisting of many free electrons or ions. As such, it is electrically conductive, and regionally charged. Move charge around (which convection does) and you generate magnetic fields, which then serve to move the charge around some more. The result is a self-generating magnetic field- a dynamo. It's not unlike the process that generates planetary magnetic fields, except that the medium is a plasma rather than a fluidic solid or liquid conductor.

Michael B. Luskin · Post by **Michael B. Luskin** » Mon Sep 19, 2016 5:16 pm

When we talk about the "surface" of a star, or, for that matter, a gaseous planet what do we mean?

Boomer12k · Post by **Boomer12k** » Mon Sep 19, 2016 5:31 pm

Michael B. Luskin wrote:When we talk about the "surface" of a star, or, for that matter, a gaseous planet what do we mean?

The top layer we generally see....we call that the "surface"... it isn't a matter of the material, but generally some "hard part" as opposed to a Gas. It is the apparent top... sometimes....like "the surface of the ocean"... or "the surface of that table"...Now with Earth, or Mars, or Venus, or a Moon, we mean the top hard rocky layer of land , water is said to cover the surface...and we don't mean the atmosphere. But I did say..."generally"... With a planet like Jupiter, it could get dicey... it does not seemingly have a solid surface. The Sun HAS a surface. It is a calcium ferrite surface layer...and is "rocky"...The photosphere is above that and is a plasma, an "atmosphere" and so covers the actual "surface of the Sun", like water.... look up... the surface of the Sun...

:---[===] *

Boomer12k · Post by **Boomer12k** » Mon Sep 19, 2016 5:34 pm

Mr. Lawrence Emailed me an answer on the size of the scope used... it is listed at the bottom of the image... a 102mm Vixen Refractor, basically a 4 inch lens, so "small scope"... we should all be more observant... including me.

:---[===] *

Chris Peterson · Post by **Chris Peterson** » Mon Sep 19, 2016 5:37 pm

Michael B. Luskin wrote:When we talk about the "surface" of a star, or, for that matter, a gaseous planet what do we mean?

The Sun consists of different layers. One of these, the photosphere, is the outermost layer which is largely transparent to visible light. It's very thin- perhaps 100 km- and the layers below are opaque. So from our vantage, the photosphere (or the layer immediately below it) appears as a surface... which we call the surface of the Sun.

neufer · Post by **neufer** » Mon Sep 19, 2016 6:22 pm

Boomer12k wrote:
Michael B. Luskin wrote:
When we talk about the "surface" of a star, or, for that matter, a gaseous planet what do we mean?
The top layer we generally see....we call that the "surface"... it isn't a matter of the material, but generally some "hard part" as opposed to a Gas. It is the apparent top... sometimes....like "the surface of the ocean"... or "the surface of that table"...Now with Earth, or Mars, or Venus, or a Moon, we mean the top hard rocky layer of land , water is said to cover the surface...and we don't mean the atmosphere. But I did say..."generally"... With a planet like Jupiter, it could get dicey... it does not seemingly have a solid surface. The Sun HAS a surface. It is a calcium ferrite surface layer...and is "rocky"...The photosphere is above that and is a plasma, an "atmosphere" and so covers the actual "surface of the Sun", like water.... look up... the surface of the Sun...

For a gaseous planet, a revolving oblate spheroid set at the point at which atmospheric pressure equals 1,000 mb (i.e., 100 kPa) is conditionally designated as the planetary "surface."

For stars (including the Sun) the surface is defined as "the edge" of the photosphere (where the optical depth ~ 2/3). The gas pressure the Sun's "surface" is only ~10 mb (i.e., ~1 kPa).

https://en.wikipedia.org/wiki/Sun#Photosphere wrote:
<<The photosphere is a star's outer shell from which light is radiated. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately 2/3. In other words, a photosphere is the deepest region of a luminous object, usually a star, that is transparent to photons of certain wavelengths.

The visible surface of the Sun, the photosphere, is the layer below which the Sun becomes opaque to visible light. Above the photosphere visible sunlight is free to propagate into space, and its energy escapes the Sun entirely. The change in opacity is due to the decreasing amount of H⁻ ions, which absorb visible light easily. Conversely, the visible light we see is produced as electrons react with hydrogen atoms to produce H⁻ ions. The photosphere is tens to hundreds of kilometers thick, and is slightly less opaque than air on Earth. Because the upper part of the photosphere is cooler than the lower part, an image of the Sun appears brighter in the center than on the edge or limb of the solar disk, in a phenomenon known as limb darkening. The spectrum of sunlight has approximately the spectrum of a black-body radiating at about 6,000 K, interspersed with atomic absorption lines from the tenuous layers above the photosphere. The photosphere is not fully ionized—the extent of ionization is about 3%, leaving almost all of the hydrogen in atomic form.>>

https://en.wikipedia.org/wiki/Hydrogen_anion wrote:
The hydrogen anion is a negative ion of hydrogen, H⁻. The hydrogen anion is an important constituent of the atmosphere of stars, such as the Sun. The ion has two electrons bound by the electromagnetic force to a nucleus containing one proton. The hydrogen anion is an important species in the photosphere of the Sun. It absorbs energies in the range 0.75–4.0 eV, which ranges from the infrared into the visible spectrum (Rau 1999, Srinivasan 1999). It also occurs in the Earth's ionosphere (Rau 1999). Its existence was first proven theoretically by Hans Bethe in 1929 (Bethe 1929). H⁻ is unusual because, in its free form, it has no bound excited states, as was finally proven in 1977 (Hill 1977).>>

ta152h0 · Post by **ta152h0** » Mon Sep 19, 2016 8:54 pm

Good destination for all the junk that is floating in the Pacific ocean, if we can get it there

neufer · Post by **neufer** » Tue Sep 20, 2016 1:09 am

ta152h0 wrote:
Good destination for all the junk that is floating in the Pacific ocean, if we can get it there

http://www.nature.com/scitable/blog/green-science/garbage_dump_in_the_middle wrote:
<<Garbage Dump in the Middle of the Pacific Ocean consists of about 3.5 million tons of trash such as light bulbs, Styrofoam cups, plastic bags, bottle caps, Popsicle sticks, bottle, cans, fishing gear, nets, buoys, and even toothbrushes.>>

3.5 million tons of Pacific junk would have to be
accelerated to ~32 km/s in order to end up in the Sun.

A railgun utilizing the total world energy power consumption
would have to run for 37 hours at a 100% efficient to do that job.

suicidejunkie · Post by **suicidejunkie** » Tue Sep 20, 2016 5:12 pm

neufer wrote:
ta152h0 wrote:Good destination for all the junk that is floating in the Pacific ocean, if we can get it there
http://www.nature.com/scitable/blog/green-science/garbage_dump_in_the_middle wrote:<<Garbage Dump in the Middle of the Pacific Ocean consists of about 3.5 million tons of trash such as light bulbs, Styrofoam cups, plastic bags, bottle caps, Popsicle sticks, bottle, cans, fishing gear, nets, buoys, and even toothbrushes.>>

3.5 million tons of Pacific junk would have to be
accelerated to ~32 km/s in order to end up in the Sun.

A railgun utilizing the total world energy power consumption
would have to run for 37 hours at a 100% efficient to do that job.

Firing junk into the sun is very wasteful.
It is significantly cheaper to fire the junk into some other star (~10% of the energy cost if I've done the math right). The hard part would be the aiming, but it is also much less dangerous if you miss.
For the impatient, I'd suggest Jupiter. You also get the benefit of watching the fireworks, with a free close up view from the orbiter if you act now!

rstevenson · Post by **rstevenson** » Tue Sep 20, 2016 5:53 pm

suicidejunkie wrote:Firing junk into the sun is very wasteful. It is significantly cheaper to fire the junk into some other star (~10% of the energy cost if I've done the math right). The hard part would be the aiming, but it is also much less dangerous if you miss....

I suspect that might be misinterpreted by the denizens of said stellar system, assuming they're of sufficient advancement to notice we're using their star as a dump.

Rob, who is firmly in favour of dealing with your own waste in your own back yard

Chris Peterson · Post by **Chris Peterson** » Tue Sep 20, 2016 5:58 pm

rstevenson wrote:Rob, who is firmly in favour of dealing with your own waste in your own back yard

Chris, who is firmly happy he doesn't have a window overlooking Rob's back yard.

Chris Peterson · Post by **Chris Peterson** » Tue Sep 20, 2016 6:02 pm

suicidejunkie wrote:Firing junk into the sun is very wasteful.

Grind it up into submillimeter particles and launch it into space near the Earth. P-R drag will cause it to fall into the Sun over a few thousand years.

Fred the Cat · Post by **Fred the Cat** » Tue Sep 20, 2016 7:29 pm

One of the mysteries of our sun is why the corona is so hot. If those vortices are related to prominences or other solar events I hope we find out exactly how they lead to the temperature out at 2 million meters.

Starship Asterisk*

APOD: 50,000 Kilometers over the Sun (2016 Sep 19)

APOD: 50,000 Kilometers over the Sun (2016 Sep 19)

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what is the surface of a star

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