The Solar Orbiter satellite imaged Mercury passing in front of the Sun on January 3. The passage of the small, dark orb sharply reveals the scale of the Solar System.
Mercury is about one-third the size of Earth and looks tiny next to the Sun’s 1,384,000 kilometers in diameter. Solar Orbiter is a mission accomplished in partnership with NASA and the European Space Agency. It was launched in 2020 and is taking measurements of solar processes with NASA’s Parker Solar Probe.
Solar Orbiter captured the transit from several different angles. Designed to study the Sun’s magnetic field, the Polarimetric and Helioseismic Imager (PHI) shows the planet as a moving sunspot as it sprints across the field of view; Capturing the intense dynamics of the Sun’s corona, the Ultraviolet Imager makes Mercury appear even smaller next to the Sun’s curve.
Another instrument aboard the orbiter, the Spectral Image of the Coronal Medium (SPICE), revealed Mercury’s transit as it passed through different layers of the sun’s atmosphere.
“In these images, we not only see Mercury passing in front of the Sun, but also passing in front of different layers of the atmosphere,” said Miho Janvier, a researcher at the Institut d’Astrophysique Spatiale.
Although Mercury is the innermost planet and orbits the Sun every 88 Earth days, it can have both extremely hot and extremely cold temperatures. Solar Orbiter images show Mercury moving at about 46.4 kilometers per second in these videos.
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