How NASA Photographs the Sun

The space agency stares right into the star, capturing these truly sublime images.

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National Journal
Brian Resnick
May 8, 2014, 1 a.m.
sun 1 National Journal

So, how does NASA take a photo of the sun?

We take a cam­era and we take a pic­ture.

It can’t be that simple, can it?

(Laughs) We take a tele­scope. The easi­est to un­der­stand is the one that takes the lovely col­or pic­tures of the corona [the out­er lay­er of the sun] that every­body likes to look at. Those tele­scopes are very sim­il­ar to the ones we use on the ground, but they have spe­cial fil­ters that al­low only this ex­treme ul­tra­vi­olet light to get through. And then they have a CCD [an im­age sensor] where the pic­tures are taken.

We have a lot of fan­ci­er elec­tron­ics, but in real­ity it looks a lot like a di­git­al cam­era.

Have we been ever been able to see the sun with such great de­tail be­fore?

We’ve been tak­ing pic­tures of the sun at these short wavelengths ac­tu­ally for quite a while. What we’re do­ing dif­fer­ently with SDO is that we are tak­ing a lot of them. It’s amaz­ing the dif­fer­ence in your un­der­stand­ing when you take a pic­ture every 12 seconds. Be­fore it was every sev­er­al hours or every 15 minutes. But, a sol­ar flare has happened in that 15 minutes and you don’t get to watch it.

Where­as now, we’re watch­ing the disk of the sun 24 hours a day with a very rap­id ca­dence. If some­body sees something, they can go get the data of what happened be­fore and what happened af­ter­wards.

Can you ex­plain the col­ors we see in these pho­tos?

Your eye can­not see these wavelengths of light. So there is no col­or as­signed to this kind of light. So we just made them up. I don’t call them false col­ors, be­cause that im­plies we are try­ing to pull one over on people. But they are coded col­ors so when we walk in­to a room, and they are show­ing im­ages from SDO, we can say “Oh, that’s the 171-chan­nel.”

They are totally ar­bit­rary. Oth­er­wise you’d walk in­to a room and there would be all these black and white im­ages and it wouldn’t be nearly as fun.

The SDO mis­sion launched in 2010. What’s something new we’ve learned about the sun since then?

My fa­vor­ite is what we call the late-phase sol­ar flare. A sol­ar flare is a bright flash of light, an amaz­ing amount of en­ergy that is re­leased very quickly. And it’s at very short wavelengths [X-rays, for ex­ample]. What we found was that if we sat and watched for a while, that same part of the sun would glow again, at longer wavelengths.

More en­ergy could come out in the second part of the flare than what was re­leased in the flare it­self. And these wavelengths are the things that af­fect our at­mo­sphere a lot. X-rays come down deep in­to the at­mo­sphere. But these oth­er wavelengths are ab­sorbed high­er up, and could af­fect things like satel­lite drag and oth­er prop­er­ties that we worry about out in space.

What the long-term goal of the mis­sion?

Our big thing is: Where does the mag­net­ic field of the sun come from, and how does it get des­troyed and ejec­ted? That’s what af­fects us.

The sun has a strong mag­net­ic field at the sur­face every 11 years, and we see that as sun spots. But we also see that as what we call space weath­er. [This sol­ar activ­ity res­ults in in­creased satel­lite drag, which can knock a satel­lite out of its in­ten­ded or­bit.] So the satel­lites that we spend so much money on to put in space come down more quickly be­cause of the drag. It af­fects our GPS nav­ig­a­tion satel­lites, and even our power grid here on the Earth.

We want to know where that space weath­er comes from. And the only way to do that is to know what is hap­pen­ing with the sun’s mag­net­ic field.

Power grid op­er­at­ors, es­pe­cially in the north­ern parts of the United States and in Europe and Canada, ac­tu­ally listen to the space weath­er people now. Be­cause they know if there’s a sig­ni­fic­ant amount of space weath­er hap­pen­ing, then they have to take pre­cau­tions. They have to isol­ate cer­tain trans­formers, they have to watch the cur­rent on their elec­tric­al trans­ition lines.

What has the pub­lic’s re­sponse to the pho­tos been like on so­cial me­dia?

We’ve got­ten an enorm­ous amount of re­sponse from the pub­lic. We take a pic­ture on SDO and people from the pub­lic are able to see it 15 minutes later, which is pretty fast for a space mis­sion.

Do you have a fa­vor­ite?

I have a fa­vor­ite movie. I call it the treb­uchet prom­in­ence erup­tion. It looks like a me­di­ev­al siege en­gine, a treb­uchet, throw­ing a load up in­to space. That one was just the coolest. It shows all this de­tail—stuff fly­ing away, stuff fall­ing back down, stuff just kind of sit­ting there as if noth­ing’s hap­pen­ing.

Is this an ex­ample of something we wouldn’t have been able to see be­fore SDO?

We couldn’t have seen it in these wavelengths and we wouldn’t be able to see the in­cred­ible de­tails of these little notches of bright­ness fall­ing down that would have been missed.

What’s next?

We’re tak­ing pic­tures of the sun, and every once in a while one of these sol­ar flares go off and it’s a mil­lion times bright­er than the stuff around it. What we would really like to have is to take pic­tures of the sun, and have the re­gion where the flare is ad­apt—to not over­ex­pose the flare re­gion.

Be­cause what we are find­ing is that flares go off and then we see waves mov­ing away from that re­gion of the sun. And those waves seem to be something ex­tremely in­ter­est­ing. But if you do a short­er ex­pos­ure to com­pensate for the flare be­ing so bright, then those waves be­come more dif­fi­cult to meas­ure.

This composite combines images from two instruments on two different solar study spacecraft to show two views of a coronal mass ejection as it blasts into space (Aug. 7, 2010). The SDO image of the Sun itself, taken in extreme UV light, shows the active region that was the source of the blast (whiter area, left of center). The larger background image, taken at about the same time, captures the front edge of he expanding particle cloud heading to the left. National Journal
When a rather large-sized (M 3.6 class) flare occurred near the edge of the Sun, it blew out a gorgeous, waving mass of erupting plasma that swirled and twisted over a 90-minute period (Feb. 24, 2011). This event was captured in extreme ultraviolet light by NASA's Solar Dynamics Observatory spacecraft. National Journal
This is an image of magnetic loops on the sun, captured by NASA's Solar Dynamics Observatory on July 18, 2012. It has been processed to highlight the edges of each loop to make the structure more clear. A series of loops such as this is known as a flux rope, and these lie at the heart of eruptions on the sun known as coronal mass ejections (CMEs.) This is the first time scientists were able to discern the timing of a flux rope's formation. National Journal
A corona mass ejection (CME), associated with a solar flare, blew out from just around the edge of the Sun today in a glorious roiling wave (May 1, 2013). National Journal
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