Satellites to create 50 solar eclipses: here’s why

The European Space Agency (ESA) is sending two satellites into orbit to emulate total solar eclipses.

ESA is working on decoding the Sun's secrets. The new Proba-3 mission aims to study the mysterious Sun's corona, the outermost part of its atmosphere, which is usually hidden by the bright light of the solar surface.

Scientists typically wait for solar eclipses to study the corona. And they, if not obscured by clouds, only last for a couple of minutes. Tired of waiting, scientists decided to simulate solar eclipses themselves.

Artificial solar eclipses

The Proba-3 mission, planned for 5th December, will use satellites flying in close formation to create artificial solar eclipses, similar to the natural eclipse when the Moon blocks the Sun.

“It’s an experiment in space to demonstrate a new concept, a new technology,” said Damien Galano, the Proba project manager at ESA, during a media briefing. “It’s very challenging because we need to control very well the flight path of the two spacecraft.”

If the satellites work according to the plan, the first will cast a shadow, allowing the other satellite to study the faint visible light coming from the corona down to just 70,000 km above the Sun’s surface.The Proba-3 satellites will circle the planet every 19.7 hours for two years, producing 50 artificial solar eclipses a year, each lasting six hours. The first images from the mission are expected as soon as March 2025.

Unanswered questions about the Sun

With this experiment, scientists hope to find out why the solar corona is way hotter than the Sun. The solar corona's temperature can reach a million degrees, while the visible surface below it is just 4500–6000 °C.

Satellites will also help to investigate what accelerates the continuous stream of plasma sent out by the Sun, called the solar winds. When the solar wind hits Earth’s magnetic field, it creates auroras, or, as we call it, northern or southern lights.

The mission will further help to study coronal mass ejections, known as solar storms. When such a storm strikes Earth, it can distort its protective magnetic field and is known to impact satellites, disrupt navigation systems, cause power outages, or bring auroras to lower latitudes.

As the satellites orbit, they will pass the inner and outer radiation belts surrounding our planet. On their way, they will measure the number, direction of origin, and energies of electrons in Earth's radiation belts to shed more light on the phenomenon. High-speed, energetic particles are constantly zipping through space and can threaten space devices by disrupting onboard systems and posing potential risks to astronauts' safety.