The latest Solar Orbiter images show the full Sun in unprecedented detail. They were taken on March 7, 2022, when the spacecraft was crossing directly between Earth and the Sun. One of the images taken by the Extreme Ultraviolet Imager (EUI) is the highest resolution image of the full disk and the outer atmosphere of the Sun, the crown, ever taken. Another image, taken by the Spectral Imaging of the Coronal Environment (SPICE), represents the first complete image of the Sun in 50 years, and by far the best, taken at the Lyman-beta wavelength of ultraviolet light emitted by hydrogen gas. The images were taken when the Solar Orbiter was about 75 million kilometers away, halfway between our world and its parent star. The EUI High Resolution Telescope captures images of such high spatial resolution that, at this close distance, a mosaic of 25 individual images is needed to cover the entire Sun. Taken one after the other, the full image was taken over four hours, as each tile takes about 10 minutes, including the time the spacecraft points from one section to another. The Sun as seen from the Solar Orbiter in extreme ultraviolet light from a distance of about 75 million kilometers. The image is a mosaic of 25 individual images taken on March 7, 2022, by the Extreme Ultraviolet Imager (EUI) High Resolution Telescope. Taken at a wavelength of 17 nanometers, in the extreme ultraviolet region of the electromagnetic spectrum, this image reveals the Sun’s upper atmosphere, the corona, which has a temperature of about one million degrees Celsius. Also included is a scale image of Earth at 2 o’clock. Credit: ESA & NASA / Solar Orbiter / EUI Team. Data processing: E. Kraaikamp (ROB) In total, the final image contains more than 83 million pixels in a 9148 x 9112 pixel grid. By comparison, this image has a resolution that is ten times better than what a 4K TV screen can display. The EUI depicts the Sun at a wavelength of 17 nanometers, in the extreme ultraviolet region of the electromagnetic spectrum. This reveals the Sun’s upper atmosphere, the crown, which has a temperature of about one million degrees Celsius. The Solar Orbiter captured images of the Sun on March 7, from a distance of about 75 million kilometers, using the instrument of the Spectral Imaging of the Coronal Environment (SPICE). SPICE receives simultaneous “spectral images” in many different wavelengths of the extreme ultraviolet spectrum by scanning the slit of the spectrometer in an area of the Sun. The different wavelengths recorded correspond to different layers in the lower atmosphere of the Sun. Purple corresponds to hydrogen gas at 10,000 ° C, blue to carbon at 32,000 ° C, green to oxygen at 320,000 ° C, yellow to neon at 630,000 ° C. Each full sun image consists of a mosaic of 25 individual scans. Represents the best full sun image taken at the Lyman beta wavelength of ultraviolet light emitted by hydrogen gas. Credit: ESA & NASA / Solar Orbiter / SPICE team. Data processing: G. Pelouze (IAS) At positions 2 o’clock (close to the Earth image for scale) and 8 o’clock at the ends of the Sun, dark threads may appear to project away from the surface. These “protrusions” are prone to explosions, dropping huge amounts of coronary gas into space and creating “space weather” storms. In addition to the EUI, the SPICE instrument also recorded transit data. And these also had to be united as a mosaic. SPICE is designed to detect layers in the Sun’s atmosphere from the crown to a layer known as a chromosphere approaching the surface. The instrument does this by looking at the different wavelengths of extreme UV light coming from different atoms. Receiving the temperature of the Sun. Credit: ESA & NASA / Solar Orbiter / SPICE team. Data processing: G. Pelouze (IAS) In the SPICE image sequence purple corresponds to hydrogen gas at 10,000 ° C, blue to carbon at 32,000 ° C, green to oxygen at 320,000 ° C, yellow to neon at 630,000 ° C. This will allow solar physicists to detect the extremely powerful explosions that take place in the corona through the lower atmosphere. It will also allow them to study one of the most enigmatic observations of the Sun: how the temperature rises through the rising layers of the atmosphere. Usually the temperature drops as you move away from a hot object. But above the Sun, the crown reaches one million degrees Celsius, while the surface is only about 5000 ° C. The investigation of this mystery is one of the main scientific goals of the Solar Orbiter. The ESA Solar Orbiter. Credit: ESA / ATG medialab The images were taken on March 7, just as the Solar Orbiter crossed the Sun-Earth line, so the images can be compared to Earth-connected solar instruments and calibrated. This will facilitate the comparison of results from different instruments and observatories in the future. On March 26, the Solar Orbiter reaches another mission milestone: its first nearby perihelion. The spacecraft is now in the orbit of Mercury, the inner planet, taking the highest resolution images of the Sun it can capture. It also records data on the solar wind of particles flowing out of the Sun. And this is just the beginning, in the coming years the spacecraft will repeatedly fly so close to the Sun. It will gradually increase its orientation to see the previously unnoticed polar regions of the Sun. The Solar Orbiter is an international space mission between ESA and NASA.
