The Sun's Hidden Firework: Unveiling the Inner Corona's Secrets
The Sun's inner corona, a region of extreme heat and mystery, has been captured in a stunning time-lapse, revealing its true colors. But here's the twist: it's not the fiery red or orange one might expect. Instead, it appears as a faint yellow, a subtle yet captivating hue. This unique perspective is brought to us by the Proba-3 mission, a duo of spacecraft from the European Space Agency with a remarkable ability.
Proba-3's spacecraft can fly in a meticulously controlled formation, creating artificial solar eclipses in orbit. This formation allows the ASPIICS coronagraph to capture images of the inner corona, which is typically hidden by the Sun's bright light. The animation showcases the inner corona in yellow, alongside the solar disc in dark orange, as seen by NASA's Solar Dynamics Observatory.
But here's where it gets controversial: the corona, despite its intense heat, can host relatively cold structures. Andrei Zhukov, from the Royal Observatory of Belgium, explains that these structures are made of plasma, still scorching at 10,000 degrees Celsius, but significantly cooler than the surrounding million-degree corona. These structures are known as 'prominences', and they can erupt, sending plasma outwards.
On September 21, 2025, ASPIICS observed an active Sun, capturing three prominence eruptions in just five hours. These eruptions are rare to witness in such quick succession, making the clear capture a significant achievement. The ASPIICS instrument uses various filters, including spectral lines, to study the corona's composition.
The animation's yellow hue is not arbitrary; it represents the spectral line emitted by helium atoms, offering a glimpse of the solar atmosphere as a human eye might see it during a total eclipse. The faint yellow glow of the corona is due to the scattering of sunlight on coronal electrons, a fascinating phenomenon.
Proba-3's onboard technologies enable it to create these artificial eclipses, providing scientists with a crucial piece of the solar puzzle. This mission fills a gap in solar observation, offering insights into the inner corona's behavior and composition. And this is the part most people miss: understanding the Sun's inner workings is essential for predicting space weather and its potential impact on Earth.
The animation, a collaboration between ESA and NASA, is a testament to the power of space exploration, revealing the beauty and complexity of our star's atmosphere. It leaves us with a question: what other secrets does the Sun hold, and how will they impact our understanding of the universe?
