Artemis II's Nikon Z9 Was Way More Important for Science Than Expected | PetaPixel

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The Planets Shine Bright — (April 6, 2026) – The Sun is eclipsed by the Moon in this April 6, 2026, image from NASA’s Orion. The glow around the Moon is called zodiacal light, which describes interstellar dust that’s reflecting sunlight. Unlike minutes-long eclipses as viewed from Earth, the Artemis II crew saw the Sun hide behind the Moon for nearly an hour. Because the astronauts were so close to the Moon (4,067 miles at closest approach), the Moon appeared much larger than the Sun; because of this, it took longer for the Sun to make its transit across the Moon and peek out the other side. From Earth, the Moon and Sun appear about the same size, so even small changes in their alignment quickly bring the Sun back into view, making totality much shorter. The two bright spots to the right of the Moon are Saturn and Mars. | Credit: NASA Researchers at Tokyo City University just published a new paper in The Astrophysical Journal Letters based on photos the Artemis II astronauts captured in space during their lunar flyby using the Nikon Z9. The researchers analyzed the solar corona images captured by the Artemis II astronauts, yielding new insights into the Sun’s coronal structure and demonstrating the value of taking cameras into space.

"We investigated the structure of the optical F-corona, i.e., inner zodiacal light, using a publicly released wide-field image of a total solar eclipse that was obtained during the Artemis II crewed lunar flyby," the researchers, Kohji Tsumura and Ko Arimatsu, write. "In this image, the solar disk is fully occulted by the Moon, providing a rare view of diffuse circumsolar emission over a wide angular extent."<br>Even though the Nikon Z9 the astronauts took into space was not fully photometrically calibrated for this type of work, the researchers were able to calibrate gamma correction using the luminance values of the background stars. This "stellar calibration" enabled them to perform extremely detailed measurements and analysis of the Sun’s F-corona.

"F" stands for "Fraunhofer," and the F-corona is the part of the corona that is "caused by dust particles scattering light from the photosphere," as the University of St. Andrews in the United Kingdom explains.<br>‘Artemis II Pilot Victor Glover, Commander Reid Wiseman, and Mission Specialist Jeremy Hansen prepare for their journey around the far side of the Moon by configuring their camera equipment shortly before beginning their lunar flyby observations.’ |Image Credit: NASA The F-corona is the brightest part of the corona "from around 1.4 million kilometers onwards from the center of the Sun," the University of St. Andrews continues.

It’s a particularly interesting part of the solar corona, as its scattered light includes Fraunhofer absorption lines, which explains the name. The F-corona’s light has the same wavelengths as sunlight seen from Earth.<br>Back to the new scientific research specifically, the researchers are interested in zodiacal light (ZL), which is a "major contributor to the diffuse brightness of the night sky" and is caused by astrophysical sources beyond Earth’s atmosphere. This brightening is actually caused by photospheric light from the Sun being scattered in space by interplanetary dust. Measuring ZL from Earth is challenging due to atmospheric conditions, making space-based observations essential, such as those conducted by the Artemis II astronauts using their Nikon Z9.<br>‘Figure 1. Top: image art002e009301 captured by the Artemis II crew during their lunar flyby at an altitude of approximately 6545 km above the lunar surface. The Moon fully occults the Sun, and the left side of the lunar disk is illuminated by sunlight reflected from the Earth. The apparent lunar diameter is 16<br>9. The glowing halo around the dark lunar disk corresponds to the F-corona (inner zodiacal light), and numerous stars are visible in the surrounding field. Bottom: the same image with an overlaid ecliptic coordinate grid. The yellow marker indicates the position of the Sun, which has an apparent diameter of and is located behind the Moon.’ Even though the Sun is a relatively close cosmic object that has been extensively studied, much about it remains mysterious, including its corona. Total solar eclipses, like the one the Artemis II astronauts experienced during their lunar flyby, provide an extremely valuable opportunity to better study the Sun.<br>It’s the same reason why the European Space Agency went through the extremely expensive and arduous process of building spacecraft to create artificial total solar eclipses repeatedly in orbit.<br>While the Artemis II mission enchanted people back home through a grand sense of adventure and awesome photos, it was, at its core, a scientific mission. A big part...