ESA’s Proba-2 captured two partial solar eclipses on 8 April 2024.
A solar eclipse occurs when the Moon passes between Earth and the Sun, totally or partially blocking the Sun from Earth’s point of view. On 8 April, lucky viewers across North America witnessed the Moon blocking out the Sun in its entirety for a few minutes, while those north and south of the ‘total eclipse path’ witnessed a partial eclipse.
Throughout the eclipse period, the Moon crossed Proba-2’s field of view twice, appearing as a partial solar eclipse. The satellite flies around 700 km above Earth’s surface in what is called a Sun-synchronous orbit, each orbit lasting around 100 minutes.
The video was produced from images taken by Proba-2’s SWAP telescope, which observes the Sun in extreme ultraviolet light. At these wavelengths, the turbulent nature of the Sun’s surface and corona – the Sun’s extended atmosphere – become visible. These measurements have to be made from space, because Earth’s atmosphere doesn’t allow such short wavelengths of light to pass through.
A total solar eclipse provides a unique opportunity to see the Sun’s corona from Earth’s surface, using visible light. As the Moon blocks most of the Sun’s bright light, the faint corona can be discerned. By comparing the SWAP ultraviolet images to what is seen by (visible light) telescopes on Earth, we can learn about the temperature and behaviour of different structures in the corona.
Other solar missions also made the most of the unique measurement opportunities provided by the eclipse. For example, ESA’s Solar Orbiter was positioned close to the Sun and at a 90-degree angle from Earth’s view throughout the eclipse. This allowed it to complement Earth-based observations by monitoring the Sun’s corona side-on, including any solar eruptions pointing in Earth’s direction.