On March 7, 2022 the European Space Agency's Solar Orbiter took a high-res image of the Sun as it passed directly between the Earth and the Sun. This allowed Earth and space-based telescopes to take pictures simultaneously so that they could all be calibrated and compared. The images included those from the amazing Inouye solar observatory, NASA’s Solar Dynamics Observatory and the joint ESA/NASA Solar Heliospheric Observatory (SOHO), located at the Lagrange (L1) Sun-Earth point.

The Solar Orbiter used the Spectral Imaging of the Coronal Environment (SPICE) imager and the Extreme Ultraviolet Imager (EUI) to give the highest full disk resolution image of the Sun, looking right down through and capturing the corona and outer solar atmosphere.

Solar Orbiter snapped images over a 4-hour session, while the probe was 75 million kilometers from the Sun, inside the orbit of Venus. One of the key mission objectives of the Solar Orbiter mission is to get some answers to the key question of how eruptions are born on the surface of the Sun, by characterizing the temperature of the Sun seen through successive layers.

Both the ESA’s Solar Orbiter and NASA’s Parker Solar Probe seek to solve two key mysteries about the sun. Why is the corona’s outer layers so much hotter than the surface of the sun’s photosphere and the process of creating the solar wind of charged particles.  (Have a listen to the ABC’s Science Show for some answers here)

The design represents the SPICE sequence showing temperature layers in color against elemental composition: yellow (neon) at 630,000 degrees Celsius, green (oxygen) at 320,000 degrees Celsius, blue (carbon) 32,000 degrees Celsius, and ‘cold’ purple (hydrogen) at 10,000 degrees Celsius. In tandem with the NASA’s Parker Solar Probe we may for instance be getting closer to understanding the reasons for the sun’s corona being hotter than the sun’s surface.

The mission comes at an auspicious time, as Solar Cycle 25 begins the journey to its peak around 2025, a good time perhaps to plan a post – pandemic visit to the northern and southern latitudes for the aurorae borealis and australis respectively.


Some ESA coverage of the Solar Orbiter Zooming into the Sun