Sun's loops are displaying an optical illusion

Jul 09, 2013
This photo of the sun's edge, taken with the Solar Dynamics Observatory Atmospheric Imaging Assembly, shows coronal loops in a variety of sizes. Although the loops appear to have a constant width, like strands of rope, new work suggests that this is an optical illusion. The loops are actually tapered, wider at the top and narrower at the bottom. Credit: NASA/SDO

(Phys.org) —The Sun's outer atmosphere, or corona, has posed an enduring mystery. Why is it so hot? The Sun's visible surface is only 10,000 degrees Fahrenheit, but as you move outward the temperature shoots up to millions of degrees. It's like a campfire that feels hotter the farther away you stand.

To understand how the is heated, some astronomers study coronal loops. These structures are shaped like an upside-down U and show where are funneling solar gases or plasma.

Our best photos of the Sun suggest that these loops are a constant width, like strands of rope. However, new work shows that this is an ; the loops are actually tapered, wider at the top and narrower at the ends. This finding has important implications for coronal heating.

"You need less energy to heat the corona if the loops have a tapered geometry, which is exactly what we found," says lead author Henry Winter of the Harvard-Smithsonian Center for Astrophysics (CfA).

Winter presented his findings today in a press conference at a meeting of the American Astronomical Society Solar Physics Division in Bozeman, Mont.

Winter and his colleagues constructed a of a tapered loop using basic physics. Then they processed their model to show how it would look when photographed by instruments like the High-resolution Coronal Imager (Hi-C) or the Solar Dynamics Observatory's Atmospheric Imaging Assembly (AIA).

They found that even the best available images wouldn't have the resolution to show the loop's true structure. As a result, a tapered loop would appear tubular even though it wasn't.

"In science we always compare theory to reality. But if your view of reality is incorrect, your theory will be wrong too. What we thought we saw could be just an effect of the instrument," explains Winter.

Historically, as we have gotten better and better photos of coronal loops, they have revealed more and more structure. What first appeared to be a single loop turned out to be made of many smaller strands. The team's work shows that better instruments with higher resolution are still needed to reveal the true shape and structure of the loops.

"Coronal loops are like Russian nesting dolls. We keep pulling them apart but we haven't gotten to the smallest one yet," says Winter.

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User comments : 8

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pdorrell
4.3 / 5 (6) Jul 09, 2013
"10,000 degrees Fahrenheit," Do I have to go to Google to find out how much that is in Celsius? ("Celsius", a temperature scale used in many countries, and also widely used scientifically.)
cantdrive85
1.3 / 5 (12) Jul 09, 2013
The only optical illusion that exists is astrophysicists understanding of what's going on here. Their ignorance is blinding, all they claim to understand is an illusion.
packrat
1.4 / 5 (9) Jul 09, 2013
"10,000 degrees Fahrenheit," Do I have to go to Google to find out how much that is in Celsius? ("Celsius", a temperature scale used in many countries, and also widely used scientifically.)


Since these articles are not really being written for scientist but laymen it makes perfectly good sense to use Fahrenheit instead of Celsius since most people in the USA still use Fahrenheit. You did notice this website is in english didn't you? Personally I prefer using Fahrenheit as it's a more understandable number to me. Celsius degrees are too far apart.
ChangBroot
3.7 / 5 (6) Jul 09, 2013
"10,000 degrees Fahrenheit," Do I have to go to Google to find out how much that is in Celsius? ("Celsius", a temperature scale used in many countries, and also widely used scientifically.)


Since these articles are not really being written for scientist but laymen it makes perfectly good sense to use Fahrenheit instead of Celsius since most people in the USA still use Fahrenheit. You did notice this website is in English didn't you? Personally I prefer using Fahrenheit as it's a more understandable number to me. Celsius degrees are too far apart.


Wow!!! It's true that this website is in English, but the world does not revolve around US A and other English speaking countries don't use Fahrenheit. Probably the US A is the only country using that nonsense system. Although I respect if they like it, but Imperial system is by far the worst. How could you say that Fahrenheit is understandable? It's the most un-understantable (if I may say so) as its name is.
packrat
1 / 5 (6) Jul 09, 2013
ChangBroot, I know it doesn't revolve around the US and never said it did. But most of the US people that I've seen comment on here tend to be older just like I am. I didn't grow up with the metric system and although I can easily use it, it simply doesn't mean much to me unless I convert it to the old system. A good example is the new hp ratings on engines that are given in metric output measurements. Hp seems to be a lot simpler to me and I understand better what the capabilities are. My kids grew up with the metric system but even they tend to use the old one most of the time. Actually I don't know anyone that uses it on a regular basis unless it's part of their job such as an auto mechanic. Most of the US still uses the old system and it's going to take the next generation to grow up before we really switch over to using the Metric system all the time like most of the rest of the world.
Bob_Kob
2.3 / 5 (6) Jul 10, 2013
This is a scientific website, all units should be in SI notation, so it should be in KELVIN.
Graeme
3 / 5 (4) Jul 10, 2013
When you get high temperatures like this it means nothing for it to be in Fahrenheit as it i way outside normal experience. And for the accuracy being so rough, Kelvin or Celsius makes no difference! They may as well use the units from the original publication.
GSwift7
not rated yet Jul 11, 2013
If you're going to get bent out of shape over farenheit temperature units, then I suggest you convert to decimal units of time and angularity as well. Unless you're a 17th century sailor, it makes no sense at all to have 360 degrees around a circle, or 24 hours in a day, or 60 minutes in an hour, etc. And the length of a second should be based on something sensible like frequency of light, or the time it takes light to travel some meaningful distance. Oh, and BTW, how arbitrary is the freakin' parsec? OMFG, our 'scientific' units make a LOT of sense.

So, yeah, go ahead and bitch about farenheit if you want, but don't pull your head up out of the sand, or you might notice that you're just as guilty of using antiquated units as anyone else.

When you get high temperatures like this it means nothing for it to be in Fahrenheit as it i way outside normal experience. And for the accuracy being ...


Exactly! Good grief, people can be so dense, can't they?

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