After successfully operating in orbit for 10 months, the scientific exploration and satellite technology achievements of China's first solar exploration scientific and technological test satellite "Xihe" were officially announced today. What did you observe from the sun on Xihe? What new contributions have these scientific exploration achievements made to human understanding of the sun? How will follow-up solar exploration activities be carried out? (the picture shows the effect of "Xihe No." Equivalent to CT scanning of the lower atmosphere of the sun, "Xihe" was launched on October 14, 2021 and operated in a solar synchronous orbit with an average altitude of 517 kilometers. As the first "photographer" dedicated to the sun, the launch of "Xihe" means that China has achieved "zero breakthrough" in solar space exploration. "In terms of scientific exploration, Xihe successfully achieved two firsts after its launch, that is, the first international acquisition of space solar H α (hydrogen alpha) band spectral scanning imaging and the first in orbit acquisition of solar H α Fine structure of spectral lines, SII (neutral silicon atom) spectral lines and Fei (neutral iron atom) spectral lines. " Zhao Jian, chief designer and deputy commander in chief of the national high resolution earth observation system and director of the earth observation and data center of the National Space Administration. Ding Mingde, chief scientist of Xihe satellite and professor of Nanjing University, told the reporter that H α Spectral lines are the most responsive spectral lines of solar activity in the lower solar atmosphere. By detecting this spectral line, we can obtain the activity information of the photosphere and chromosphere at the same time, which greatly improves our understanding of the physical mechanism of solar eruption. "For H α The detection of spectral lines can only be carried out on the earth. It is disturbed by the atmosphere, and the detection data are often discontinuous and unstable. " Zhao Jian introduced that the main scientific load of "Xihe" is sun H α Imaging spectrometer, through spectral scanning imaging, the resolution reaches 0.0024 nm, which is about 10 times higher than the resolution of the ground filter and reaches the international advanced level. Each spectral scanning image actually contains more than 300 photos, which correspond to the solar images at different heights of the photosphere and the chromosphere, so it is equivalent to CT scanning of the lower atmosphere of the sun. Each "CT map" reflects the information of nearly 16 million points on the daily surface. Except sun H α Spectral lines, "Xihe No." also obtained SII spectral lines and Fei spectral lines at the same time. In particular, the SII spectral line was covered by the water molecular spectral line of the earth's atmosphere during ground observation in the past. The Xihe spacecraft directly observed the complete spectral line profile of SII in space, which is the first time in the world. Through the study of the three spectral lines, combined with the Doppler velocity maps of the whole solar surface chromosphere and photosphere obtained by the "Xihe" spacecraft, the temperature, density and velocity of the solar atmosphere can be inversely calculated, thus helping us to deeply study the atmospheric structure of the sun, understand the cause and propagation process of solar eruptions, better carry out space weather prediction, and ensure human life safety. Experts said that the relevant tests carried out by the "Xihe" satellite in orbit were the first time in the world that H α At present, the spectral line research has obtained two international scientific achievements in solar exploration, which has significantly improved China's international influence in the field of solar physics