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How close can we actually get to the Sun?

TED-Ed • 5:48 minutes • Published 2025-06-26 • YouTube

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Surfing the Solar Winds: How the Parker Solar Probe is Unlocking the Sun’s Secrets

The Parker Solar Probe is not just any spacecraft—it holds the record as the fastest human-made object ever, hurtling through space at an astonishing speed of over 630,000 kilometers per hour. That’s more than 500 times the speed of sound on Earth! Its ambitious mission? To get closer to the Sun than any spacecraft before it, to literally “touch” the Sun’s atmosphere without succumbing to the intense heat.

A Historic Journey Into the Sun’s Corona

In 2021, the Parker Solar Probe achieved a groundbreaking milestone by flying through the Sun’s corona—the outermost layer of its atmosphere—after performing a flyby of Venus. Since that daring feat, the probe has been steadily inching closer to the Sun, revealing new and extraordinary details about our star.

During its closest approaches, the probe is projected to venture within just 8.8 solar radii—less than 4.5 times the diameter of the Sun itself. At this proximity, it must endure searing temperatures reaching 1,500 degrees Celsius. However, even this remarkable feat has its limits, as the probe’s heat shield can only protect it up to a point.

Mysteries of the Sun’s Outer Atmosphere

One of the most puzzling discoveries about the Sun is that its surface is actually cooler than the outer corona. Above the solar surface lies a thin, roughly 100-kilometer layer called the transition zone, where temperatures plunge from a blazing 500,000°C down to a “cooler” 8,000°C. Scientists have theories about how this zone forms, but definitive answers require even closer observations.

Some researchers speculate that if a spacecraft could fly within about 3 solar radii of the Sun and execute a carefully timed rocket burn, it could harness the Sun’s gravity in a maneuver known as the Oberth maneuver. This could potentially catapult the spacecraft beyond Pluto in just three years—a journey that currently takes about a decade.

Engineering Marvels: How Parker Survives the Heat

Getting close to the Sun without melting or being flung off into space is a monumental engineering challenge. The probe’s trajectory is carefully planned through a series of intricate orbital maneuvers around Venus, using the planet’s gravity as a brake to slow down and adjust its path incrementally closer to the Sun.

To withstand the intense heat, the Parker Solar Probe uses a heat shield only 4.5 inches thick, designed much like a high-tech beach umbrella. One side is coated with a highly reflective white ceramic to scatter incoming sunlight. The other side features carbon foam sandwiched between carbon layers reinforced with carbon fiber. This foam, which is about 97% air, acts as an excellent insulator, preventing heat from penetrating to the instruments inside. The outer carbon panel absorbs and radiates any remaining heat back into space. A sensor system continuously adjusts the shield to keep the probe’s sensitive instruments safely in shadow.

Pushing the Limits: New Materials for Even Closer Solar Encounters

While Parker’s heat shield is impressive, it can only get so close to the Sun. To push even further, NASA’s Innovative Advanced Concepts program is developing new materials like Solar White, an ultra-reflective coating predicted to reflect 99.9% of the Sun’s energy. By combining this with a second, silvered conical shield, this double-layer defense system could potentially allow probes to approach as close as 2 solar radii.

These advancements could unlock the long-standing mystery of the transition zone and significantly improve our ability to predict solar flares and geomagnetic storms—events that can disrupt satellites and communication systems on Earth.

Looking Ahead: The Sun as a Gateway to the Solar System

The Parker Solar Probe’s journey is more than just a feat of engineering; it is a giant leap toward understanding our closest star. By probing deeper into the Sun’s atmosphere, we stand to gain unprecedented insights into solar behavior and its effects on our planet. Moreover, mastering close solar encounters could open the door to bold new missions, using the Sun’s gravity to slingshot spacecraft to the farthest reaches of our solar system—and beyond.

As we continue to push the boundaries of exploration, the Sun not only illuminates our days but may also become a powerful ally in our cosmic journeys. The Parker Solar Probe’s voyage is just the beginning of this thrilling adventure.

📝 Transcript (76 entries):

The Parker Solar Probe, the fastest object ever made by human hands, surfs the solar winds at more than 630,000 kilometers per hour. That’s more than 500 times the speed of sound on Earth. Its mission? To touch the Sun— and, ideally, to avoid melting in the process. It achieved this goal in 2021, when the probe flew by Venus and skimmed through the corona, the Sun’s outermost atmosphere. Since then, it's carved closer and closer paths, revealing extraordinary details about our star in the process. On its closest approach, it’s projected to cross within 8.8 solar radii— that’s less than 4.5 sun lengths away from the solar surface. And it will endure temperatures of 1,500 degrees Celsius. But there’s a limit to just how close Parker can get. And there are questions scientists can't answer without probing even deeper into the solar atmosphere. Among these mysteries is the astonishing fact that the solar surface is actually much cooler than the outer corona. Above the solar surface is a thin 100 kilometer layer known as the transition zone, where temperatures dip from a scorching 500,000°C to a relatively cool 8,000 degrees. While physicists have theories on how the transition zone forms, we won't know for sure until we can make closer observations. Further, some scientists predict that if a spacecraft could fly within about 3 solar radii from the Sun’s surface and fire its rockets at just the right time, it could use the Sun’s gravity to slingshot itself into the outer solar system. This daring flight path, called the Oberth maneuver, could propel a spacecraft past Pluto in just three years, a trip that currently takes around a decade. But probing deeper into the corona— without melting, exploding, or falling directly into the Sun— is a monumental engineering challenge. The first challenge is directing the probe's path. A probe falling directly towards the Sun would likely pick up so much speed in its descent that it would either crash or be flung in the opposite direction. To avoid this, the Parker Space Probe made a series of complicated orbital maneuvers around Venus. Using the planet’s gravity as a brake, it could readjust its orbit and get incrementally closer. But these current orbital tricks can only get us so far. As for the scorching heat, the Parker Probe used a strategy that is not unlike sitting under a beach umbrella. Its instrumentation is packed behind a heat shield just 4.5 inches thick. One side is made of highly reflective white ceramic that scatters much of the incoming sunlight. The other side consists of a carbon foam sandwiched between two layers of carbon, further reinforced with carbon fiber. The foam is around 97% air, so it acts as an insulator, not allowing much heat to flow through. The outer carbon panel is very dark and can withstand high temperatures, so it efficiently absorbs any remaining heat and radiates it back out to space. A sensor system constantly adjusts this shield to ensure the craft’s instruments remain in its shadow. But Parker’s heat shield can only get so close. To get even closer, one possibility would be to ditch the heat-absorbing carbon materials entirely and double down on deflection. Researchers at NASA’s Innovative Advanced Concepts program have developed a novel ultra-reflective coating called Solar White that’s predicted to reflect 99.9% of the Sun’s energy. They plan to use Solar White to coat an outer curved umbrella-like shield. Then, a second conical shield made from a silvered reflective material would shunt away any remaining radiation that escapes through. With both novel shields, scientists believe they could surf a probe as close as 2 solar radii from the surface. But we won’t know for sure until these materials are further tested. At these close distances, we might unlock the mystery of the transition zone. We may learn how to better predict solar behaviors like flares and geomagnetic storms, which puts satellites and our communication systems on Earth at risk. And we’d get an unprecedented look at our star, and perhaps one day, with the Sun’s assistance, at our most distant neighbors.