New Solar Telescope Reveals Sun’s Surface in More Detail than Ever Before

A new solar telescope in Hawaii has captured images of the sun unlike any seen before.

Late last month, astronomers working with the Daniel K. Inouye Solar Telescope released the most detailed images of the sun’s surface ever taken. The images reveal a bubbling surface of hot plasma that looks like slowly simmering nuggets of gold.

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The telescope was funded by the National Science Foundation and is positioned on the summit of Haleakala. It will enable a new era of solar science exploring the inner workings of the sun and how activity on its surface can generate space weather that can impact satellite communications and even disable power grids on Earth.

Professor Robert Rosner, an astrophysicist at the University of Chicago and one of the lead investigators on the project, says he’s been waiting for almost 40 years to see images like the ones recently captured.

“Those of us fascinated by the sun – and who would not be? – have been waiting since the 1980s to see the sun at high resolution, to see if the amazing structuring of the surface, from the grand sunspots down to the ‘salt and pepper’ smaller magnetic structure, continues to yet smaller spatial scales. And it does!” said Rosner. “The physics to be mined from this result, these remarkable images, are just so exciting.”

The new telescope is far more powerful than what was previously the largest U.S. solar telescope and can gather seven times as much light. Unlike most telescopes, the Inouye Solar Telescope has an off-axis mirror approximately four meters across.

“The reason we need to do this is that when you are looking at the sun the amount of light that is being gathered is just enormous,” said Rosner. “This thing receives about 12,000 watts of energy – so if that amount of energy went through the lens system it would basically just melt them all. So you need to figure out an optical design that basically can deal with that. And this off-axis design with what’s called a heat dump or heat stop allows you to do that.”

The sun is essentially a giant nuclear reactor that burns roughly five million tons of hydrogen every second. All of that energy then radiates into space and the small fraction that hits the Earth is what makes life on our planet possible.

But the impact of the sun is not always benign. Solar storms created by the interaction of the sun’s plasma with its strong magnetic fields can lead to solar flares and so-called coronal mass ejections that can be immensely damaging if they happen to strike the Earth.

“They can interfere with satellite communication. They can actually destroy satellites. They can effect national electrical grids as they did some years ago with the Canadian grid,” said Rosner.

That’s why one of the goals of the project is to better understand the processes within the sun that create solar flares and other solar weather so that in the future we may be better able to forecast potentially damaging events.

“If we see a very large solar flare we see that flare about eight minutes after it has occurred on the sun because that’s the light travel time from the sun to us,” said Rosner. “The stuff that is ejected moves much more slowly. The fastest things that follow the light are accelerated particles and they go about a third of the speed of light. So they take about 20 minutes to get to us. So when we see such an event we have about 12 minutes – 20 minutes minus eight minutes – to react. And one of the things we would do would be to turn off some satellites until the event was over.”

But in the future, Rosner hopes that by better understanding the precursors that lead up to a solar flare or a plasma ejection would give more lead time in order to prepare for such events.

“This is the key motivation and the science behind this telescope,” said Rosner.

Beyond the practical reasons for wanting to know more about our sun, there’s also simple human curiosity.

“Simply trying to figure out how this object that keeps us alive, how does it actually work?” said Rosner. “Why does it look the way it does? What about the magnetic field – how does that interact with this hot plasma? So these are fine questions that nerds like me are very interested in trying to answer.”

And with the new Inouye Solar Telescope, NASA’s Parker Solar Probe, which last month passed closer to the sun than any other spacecraft, and the launch Sunday of a new solar orbiter by the European Space Agency, there has never been a better time to be a solar scientist.

“I’m so lucky to be still around having waited for this for all these years,” said Rosner. “One of the things about astronomy is that astronomers are remarkably patient people and we planned for this in the late 1980s – the work leading to this telescope was started around this time. And you just have to be patient because these are big projects that are enormously expensive … And we were patient and we were rewarded. It’s really gratifying and one thing that it means is that there will be a huge uptick of interest in solar science.”

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