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It's the TED Radio Hour from NPR. I'm Manoush Zomorodi. Today on the show, an exploration of one of the most powerful forces in our lives - the sun. Starting on September 1, 1859. That day, a British astronomer named Richard Carrington was looking at the sun and sketching sunspots, the dark patches on the solar surface.

NOUR RAWAFI: He was watching through his telescope and drawing them by hand.

ZOMORODI: It was a bright light that lasted for nearly five minutes.

RAWAFI: And he just was mesmerized of this new thing that he'd never seen before.

ZOMORODI: Carrington had no idea what it was until the next day when strange things started happening.

ZOMORODI: Electric currents zipped through telegraph wires, setting telegraph stations on fire. Communications the world over were knocked out. Meanwhile, bright colored lights - aurorae - lit up the sky.

RAWAFI: People were seeing aurorae in daytime around the whole globe.

ZOMORODI: The New York Times described them as streamers, rapidly changing hue from red to orange, orange to yellow, yellow to white, back to brilliant red. In the Rocky Mountains, the sky was so bright at midnight that confused gold miners woke up and started making breakfast. Carrington connected the dots and hypothesized that the bright light he'd seen was a solar flare, a storm on the sun so powerful that the radiation it released reached the Earth, disrupting the magnetic fields that surround our planet.

RAWAFI: But there were a lot of skepticism. It took really decades afterwards to realize, yeah, actually, we are connected to the sun.

ZOMORODI: Carrington was eventually proven right. This incident is now referred to as the Carrington Event, and it is the strongest geomagnetic storm ever recorded. Meaning if it were to happen today...

RAWAFI: In some places, people will be out of power for months, maybe for even years, and the economic losses will be in the trillions of dollars. Nowadays, we depend a lot on satellites, communication satellites or GPS satellites over there in space. So these geomagnetic storms can impact technology in space. And one prime example of this is the loss of SpaceX of nearly 40 satellites in 2023 or '24. That actually was the result of a geomagnetic storm.

ZOMORODI: So solar storms can spell disaster. But the good news is that now, scientists like Nour Rawafi at NASA are constantly monitoring sun storms.

RAWAFI: We know what the sun does at any moment. When there is an explosion, a flare or coronal mass ejection, we see it. We know what direction they are going, how powerful they are, how fast they are and we can even predict what would be the impact here on the Earth environment.

ZOMORODI: But Nour and his team also have a spacecraft that is orbiting the sun and is due to fly closer to it than ever before, collecting data so that we can better understand why these storms happen and solve other solar mysteries.

RAWAFI: Without the sun, there will be no life on Earth. There will be no solar system. There will be no Earth. So in a way, we are the sons of the sun.

RAWAFI: It's our star. We owe our existence to the sun, but also our daily life depends on it.

ZOMORODI: The sun is at the center of our solar system. It rises and sets on every day of our lives. We worship it, absolutely have to have it, but there is so much we don't know about this massive star that we depend on. So today on the show, making sense of the sun, what powers it, and how we can replicate and harness that power. So back to Tunisian astrophysicist Nour Rawafi and his team of international scientists at NASA. Their spacecraft, the Parker Solar Probe, has been orbiting the sun for the past six years, completing a full revolution around it every three months. And on Christmas Eve, 2024, it is due to touch the sun.

RAWAFI: Since the dawn of the space age, NASA has wanted to fly a spacecraft as close as possible to the sun.

RAWAFI: But getting very close to a star is extremely risky and really hard. How would we protect a probe from just melting? How could it adjust for any problem on its own when you cannot communicate with it? Until recently, we simply didn't possess the technology. In 2018, that all changed with the launch of Parker Solar Probe. Parker Solar Probe is the first spacecraft to ever fly through the solar corona. It has revolutionized our understanding of the sun.

ZOMORODI: So the probe is roughly the size of a small car, and making sure it wouldn't go up in flames as it approached the sun was an engineering feat.

RAWAFI: The only thing standing between the probe and incineration is an ingenious 11.5-centimeter thick, 2.3-meter-wide carbon foam shield. On Christmas Eve 2024, the shield's sun-facing side will endure about 1,000 degrees Celsius.

ZOMORODI: The shield reflects light, absorbs heat and is cooled by a network of water-filled pipes.

RAWAFI: All this system will be operating on December 24, 2024, when Parker Solar Probe achieves humanity's closest-ever approach to a star. This will be a monumental and audacious achievement. In '69, we land humans on the moon. In '24, we're going to embrace a star.

ZOMORODI: It's being described as an attempt to touch the sun. Is that accurate?

RAWAFI: Well, we are flying within the solar corona, so the solar corona is part of the sun. So we are flying through it. We are touching the atmosphere of the sun.

ZOMORODI: And what information will be coming back to you?

RAWAFI: Parker Solar Probe have a whole suite of instruments around it. We have an imager, a white light imager that will image the solar wind and all that solar activity that happens as it propagates from the sun all the way out. We have also instruments that measure magnetic fields, temperatures, densities, fluctuations, velocities, energetic particles that are flying almost at the speed of light.

ZOMORODI: How does it send back all of this data to you?

RAWAFI: That is a challenge for us because the geometry doesn't allow us to talk to the spacecraft all the time. So we need the spacecraft to be in certain areas of space when the antenna can point to Earth. That way, we can communicate. And basically, we send information to the spacecraft. The spacecraft can send us data and information as well.

RAWAFI: The sun holds over 99.8% of the solar system's total mass. Its sheer size is mind-boggling, requiring more than 1.3 million Earths to fill its volume. All of that mass is in the form of plasma, a glowing soup of electrically charged particles. At the solar core, gravity is exceedingly high, producing temperatures in excess of 15 million degrees Celsius. The solar surface is plenty hot, 6,000 degrees, hot enough to melt anything we know. But in the corona, we're talking millions of degrees Celsius.

How can it be over 300 times hotter despite being the sun's outermost layer? Physicists have suggested since the '50s that all of that heat must generate a constant outflow of particles. This is a solar wind. It spits away at up to 3 million kph. At that speed, you can get from the Earth to the moon in under 20 minutes. Behind all this is the sun's magnetism. As solar magnetic fields twist, bend and tangle, they store enormous amounts of energy. And when they snap, huge explosions like flares and coronal mass ejections release this energy and turn it into heat and accelerating the plasma.

It takes only a handful of these strong events to fulfill our current energy needs for some 200,000 years. That is the whole span of modern human's existence. The sun does that in minutes to few hours. These same explosions propel particles to nearly the speed of light and turns them into formidable hazard to spacecrafts and to humans in space. Our power grid can fall victim, like in March 1989 in the northeast of the U.S.-Canada, when a succession of solar storms caused an intense geomagnetic storm. So we need to learn how the sun does all this and more.

ZOMORODI: What is the prediction in terms of solar flares and storms in the next decade or so?

RAWAFI: Well, we are at the solar maximum now. And that's actually one of the big mysteries when - is predicting how strong the solar cycle will be. That's one of the big things that we - now we are trying to understand, but it's not really an - easy at all. So we need some new missions to help us understand what is going on in the interior of the sun itself and observe the sun for a long time from different viewpoints to come to terms how the magnetic fields form in the solar interior and how they rise to the surface and how - what is the source of their cyclic nature. And if you think of it, Parker Solar Probe is flying through origin of space that we never visited before. And whatever measurement we make there might actually carry with it a potential discovery for us.

ZOMORODI: You have a look of absolute delight on your face as you're describing this. Did you think you would learn these things in your lifetime?

RAWAFI: Sometimes it's still kind of - it's like a dream, but you are living it. And the fascinating thing about Parker Solar Probe is also that the pace of the mission is so fast. So every three months, we have a fly-by around the sun, and we have a new load of data. We are like spoiled kids in a way.

RAWAFI: Whenever we get a new load of data, we jump on it. We are so curious what is new in it. The data we are getting from it is so loaded with knowledge, with new things that we need to investigate, that is going to take us decades from now to look into it. And in a way, Parker Solar Probe will serve for generations to come, many generations to come. And for me, Parker Solar Probe is a mission for the ages.

ZOMORODI: That was astrophysicist Nour Rawafi. He is a senior scientist at the Johns Hopkins Applied Physics Laboratory and the project scientist for NASA's Parker Solar Probe. You can learn more about the Parker Solar Probe mission at science.nasa.gov/sun, and you can see Nour's full talk at ted.com. On the show today - The Sun. I'm Manoush Zomorodi, and you're listening to the TED Radio Hour from NPR. We'll be right back.

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