Two eclipse-making robotic satellites have just captured their first images from Earth orbit

The European Space Agency (ESA) has released the first images from its Proba-3 mission, which produces artificial solar eclipses in space.

Proba-3 consists of a pair of small satellites that make solar eclipses, enabling solar scientists to get a better view of the Sun's outer atmosphere.

These first Proba-3 images offer new views of the Sun’s mysterious inner corona, the fiery halo of plasma surrounding our star, captured not during a natural eclipse, but during one made by space probes.

Launched in December 2024, Proba-3 is the latest in ESA’s PRojects for OnBoard Autonomy, a series of small, innovative missions that test cutting-edge technologies in orbit around Earth.

Proba-3 is the third Proba mission launched so far, and consists of two spacecraft flying in formation, separated from one another by just 150m.

How Proba-3 works

How do you create an artificial solar eclipse using two spacecraft?

One satellite, called the Occulter Spacecraft, carries a 1.4-metre-wide disc that positions itself in front of the Sun and blocks out the entire solar disk.

The other, the Coronagraph Spacecraft, follows behind with a telescope pointed at the silhouette created in front of the Sun by the Occulter.

The pair stay precisely aligned, blocking out the Sun’s most intense glare and revealing the ghostly inner corona, giving solar scientists an unprecedented view of this region of the Sun's atmosphere.

This formation is maintained autonomously by the probes using star trackers, cameras, lasers and photo detectors.

Small thrusters on both spacecraft make constant adjustments to keep the 'eclipse' in place for up to six hours at a time, for every 19hr 36min orbit of Earth.

The view is then recorded by Proba-3's optical instrument ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun).

Why Proba-3 is a solar science dream

In May 2025, ESA engineers celebrated as Proba-3 achieved precise formation flying for the first time, confirming that the pair of probes would be able to produce and maintain artificial solar eclipses autonomously.

Now, the first fruits of that milestone are here.

But these are more than just pretty pictures. The corona – the Sun's outer atmosphere – holds some of the biggest mysteries in solar physics.

One mystery is known as the 'coronal heating problem', whereby the Sun's corona is hotter than the layers below, and no-one has confirmed why this is the case.

The corona is also the source of coronal mass ejections, powerful bursts of energy from the Sun that hit Earth's atmosphere and can disrupt satellites, power grids and even be a danger to astronauts in orbit.

But the main body of the Sun is so much brighter than the corona, so solar scientists are left with the problem of how to get a good look at it.

One way is to wait for a solar eclipse, when the Moon blocks out the Sun, leaving only the wispy streams of the corona in view.

Since total solar eclipses don't come about every day, the solution is Proba-3, which creates artificial solar eclipses that last hours, rather than minutes.

Using coronagraphs

Coronagraphs are oft-used instruments in solar science; effectively a black circle that blocks out the Sun's disk, leaving just the outer corona in view.

But diffraction, the bending of stray solar light around the edges of the disc, makes it difficult to see the inner corona.

Proba-3 solves this problem by positioning the coronagraph further away.

In fact, solar scientists say that Proba-3's observing distance is about twice as far as that of any other coronagraph.

About Proba-3's first images

These Proba-3 images were processed by the ASPIICS Science Operations Centre (SOC) hosted by the Royal Observatory of Belgium.

"I was absolutely thrilled to see the images, especially since we got them on the first try," says Andrei Zhukov, Principal Investigator for ASPIICS.

"Now we are working on extending the observation time to six hours in every orbit.”

"Each full image – covering the area from the occulted Sun all the way to the edge of the field of view – is actually constructed from three images.

"The difference between those is only the exposure time, which determines how long the coronagraph’s aperture is exposed to light. Combining the three images gives us the full view of the corona.

"Our 'artificial eclipse' images are comparable with those taken during a natural eclipse.

"The difference is that we can create our eclipse once every 19.6-hour orbit, while total solar eclipses only occur naturally around once, very rarely twice a year.

"On top of that, natural total eclipses only last a few minutes, while Proba-3 can hold its artificial eclipse for up to 6 hours."

Proba-3 mission manager Damien Galano says: "Having two spacecraft form one giant coronagraph in space allowed us to capture the inner corona with very low levels of stray light in our observations, exactly as we expected.

"Although we are still in the commissioning phase, we have already achieved precise formation flying with unprecedented accuracy.

"This is what allowed us to capture the mission’s first images, which will no doubt be of high value to the scientific community.

"The formation flying we have achieved so far was performed autonomously, but under supervision of the ground control team, who were ready to intervene to correct any potential deviations.

"Our one remaining task is to achieve full autonomy, when our confidence in the system will be such that we will not even routinely monitor from the ground."

Beyond the eclipse

Alongside its coronagraph, Proba-3 carries two other instruments.

One is the Digital Absolute Radiometer (DARA), which monitors the Sun’s total energy output, a key metric for climate models.

It also has the 3D Energetic Electron Spectrometer (3DEES), which studies electron fluxes in Earth’s radiation belts, providing information about space weather and its effect on space-travelling astronauts.

Proba-3 is expected to operate for 2 years and will collect data during each of its 19-hour orbits.

When the mission ends, the two satellites won’t become space junk.

They’ll naturally fall back toward Earth and burn up in the atmosphere within 5 years, in line with ESA’s 'Zero Debris' policy.

Proba-3 has 2 years of hard work in front of it, but these first images show that all seems to be working smoothly, and that solar scientists could be on the way to uncovering some of the greatest secrets of the star that enabled life to flourish on our planet.