Solar Orbiter: Camera 'hack' leads to a new view of the Sun

"It was really a hack," said Frédéric Auchère, Institut d'Astrophysique Spatiale, Université Paris-Sud, and a member of the EUI team.

"I had the idea to just do it and see if it would work. It is actually a very simple modification to the instrument." This process included attaching a tiny, lightweight 'thumb' to the instrument's door. 

When the door opens to allow light into the camera, if it stops halfway, this thumb shields the Sun's bright center, enabling the EUI to capture the much fainter ultraviolet light emitted by the surrounding corona, which is a million times dimmer.

The image, taken in ultraviolet light, displays the Sun's corona with impressive clarity. What sets this image apart is the simultaneous superimposition of an ultraviolet image of the Sun's disc, captured by NASA's STEREO mission. 

This convergence of data from these two missions provides scientists with a valuable opportunity to study the Sun's complex dynamics.

Solar Orbiter's EUI occulter mode extends the reach of solar observation, allowing scientists to explore the Sun's atmosphere deeper. 

This region, largely uncharted due to its location beyond the typical field of view of Extreme Ultraviolet (EUV) imagers and the interference of conventional coronagraphs, holds significant scientific potential.

"We have demonstrated that this approach can effectively combine Sun and corona imaging in a single instrument," said Daniel Müller, ESA's Project Scientist for Solar Orbiter. Such integration could enhance solar observation methods considerably.

The alignment of Solar Orbiter and STEREO missions during image capture is a testament to the precision of space science endeavors. 

Both missions coincidentally observed the Sun from nearly identical perspectives, resulting in a close correspondence between surface features of the Sun and those within its corona.

Capturing the Sun's corona

Traditional solar coronagraphs have been the standard for capturing images of the Sun's corona. Solar Orbiter possesses its own coronagraph, known as Metis. 

However, EUI's occulter mode presents a more versatile approach to solar observation by merging the capabilities of imaging the Sun and its corona into a single instrument.

David Berghmans, the EUI Principal Investigator from the Royal Observatory of Belgium, highlights the potential for scientific discoveries: "Physics and magnetic structures in this region are poorly understood, and this novel approach offers an unprecedented opportunity to study it in depth."

As Solar Orbiter progresses in its space journey, we anticipate a wealth of knowledge and captivating images that will further enrich our comprehension of the Sun's enigmatic corona.