Solar Orbiter takes images of the Sun with unprecedented resolution

Writing Science, 24 Mar The European probe Solar Orbiter has taken new images of the Sun with unprecedented resolution when it was 75 million kilometers from our star. The images show both the entire disk of the Sun and its outer atmosphere, the corona, and in others they collect the different temperatures that are recorded in the star. The highest resolution was made on March 7 by the High Resolution Telescope (EUI), an extreme ultraviolet camera while those made by the Coronal Environment Spectral Imaging (SPICE) apparatus are the most complete of their kind taken from our star in 50 years. Solar Orbiter, from the European Space Agency (ESA), was launched in February 2020 to deepen knowledge about the Sun, which is now about 75 million kilometers away, halfway between the star and the Earth. The EUI takes images of such high spatial resolution that, at that short distance, a mosaic of 25 individual images is needed to cover the entire Sun. The entire image was captured over a period of more than four hours, as each tile takes about ten minutes, including the time to point from one segment to the next. In total, the final image contains more than 83 million pixels on a 9148 x 9112 pixel grid, which is ten times better resolution than a 4K television screen can display. The EUI takes images of the Sun at a wavelength of 17 nanometers, in the extreme ultraviolet region of the electromagnetic spectrum, revealing the upper atmosphere of the Sun, called the corona, which has a temperature of about one million degrees. The SPICE instrument, for its part, is designed to trace the layers of the Sun's atmosphere from the corona to the chromosphere. In the SPICE image sequence, purple corresponds to hydrogen gas at a temperature of 10,000 degrees; blue to carbon to 32,000; green to oxygen to 320,000 and yellow to neon at 630,000 °C. These data will allow solar physicists to track the extraordinarily powerful eruptions taking place in the corona through the lower atmospheric layers. They will also be able to study one of the secrets of our star. Normally, the temperature drops as we move away from a hot object, but above the Sun, the corona reaches a million degrees, while the surface is only about 5,000 degrees. Investigating this mystery is one of the key objectives of Solar Orbiter. The probe took these images at the time it crossed the Sun-Earth line, allowing its results to be compared with those obtained by instruments located on Earth. On March 26, Solar Orbiter will reach another mission milestone, its first near perihelion, and is now within Mercury's orbit. Thanks to its various instruments, the probe is also recording data on the solar wind, a continuous flow of energetic particles emitted by the solar corona.