From its outpost 1.5 million\u00a0km\u00a0away\u00a0from Earth\u00a0in the direction of\u00a0the Sun, SOHO enjoys uninterrupted views of our\u00a0star. It has provided\u00a0a\u00a0nearly continuous\u00a0record of our Sun\u2019s activity for close to three 11-year-long\u00a0solar cycles<\/a>.\u00a0<\/p>\n “It is testament to the ingenuity of our engineers, operators and scientists, and to international collaboration, that this mission has exceeded all expectations,” says Prof. Carole Mundell, ESA Director of Science. “SOHO\u00a0has overcome nail-biting challenges to become one of the longest-operating space missions of all time.”\u00a0<\/p>\n “The SOHO mission is a great example of the incredible partnerships between NASA and ESA,\u201d adds Nicky Fox, associate administrator, Science Mission Directorate at NASA Headquarters in Washington. “Congratulations to the NASA and ESA teams on an amazing thirty years working together.”\u00a0<\/p>\n \t\t\t\t\t\t\tSOHO’s 30 years in numbers <\/a><\/p>\n The mission has not been without drama. Two-and-a-half years after launch, the spacecraft suffered\u00a0a critical error<\/a>, spinning out of control and losing contact with Earth. An international rescue team worked tirelessly for three months to\u00a0locate\u00a0and\u00a0recover\u00a0it.\u00a0\u00a0<\/p>\n Then, in November & December 1998,\u00a0the spacecraft\u2019s\u00a0stabilising\u00a0gyroscopes failed\u00a0and a new race to save the mission began.\u00a0By\u00a0February 1999<\/a>, new software enabled the spacecraft to fly without the need for gyroscopes, and it has been\u00a0revolutionising solar science\u00a0ever since.\u00a0\u00a0<\/p>\n \u201cSOHO pioneered new fields in solar science. It is\u00a0a game-changer\u00a0in the study of\u00a0space weather<\/a>, providing real-time monitoring of the Sun to forecast potentially dangerous solar storms heading towards Earth, and its legacy continues to guide future missions,\u201d says Daniel M\u00fcller, ESA Project Scientist for\u00a0SOHO<\/a>\u00a0and\u00a0Solar Orbiter<\/a>.\u00a0\u00a0<\/p>\n \u201cSOHO is still producing high-quality data on a daily basis, and with hundreds of papers being published every year, its scientific productivity remains very high.\u201d\u00a0\u00a0<\/p>\n Daniel\u2019s new paper\u00a0\u2018SOHO\u2019s 30-year legacy of observing the Sun\u2019<\/a>\u00a0is published in Nature Astronomy\u00a0on\u00a0Tuesday 2 December 2025. Text continues after image<\/p>\n \t \t\t\t\t\t\t\t30 years of SOHO imaging the Sun<\/a><\/p>\n <\/p>\n Here are five highlights from the last five years:\u00a0<\/p>\n \t1. A single plasma conveyor belt <\/p>\n SOHO led the way in \u2018helioseismology\u2019.\u00a0Akin to studying how seismic waves traverse\u00a0Earth\u00a0during an earthquake, helioseismology probes\u00a0the\u00a0inside of the Sun\u00a0by studying how sound waves reverberate through it. Early in its career, SOHO provided the first images of plasma flows (electrically charged material) beneath the Sun\u2019s surface, offering a unique window into its layered interior.\u00a0<\/p>\n Thanks to SOHO\u2019s long lifetime, scientists have used\u00a0helioseismology\u00a0to\u00a0solve an enduring mystery<\/a>: plasma flows along a single loop, or cell, in each of the Sun’s hemispheres \u2013 not multiple cells as previously thought.\u00a0\u00a0<\/p>\n The data show that it takes about 22 years for plasma to complete an entire loop around this single \u2018conveyor belt\u2019, flowing from the surface near the equator up to the poles, then traveling back down deep inside towards\u00a0the equator. This matches the timeline of the\u00a0Sun\u2019s magnetic cycle<\/a>, explaining how sunspots \u2013 regions where intense magnetic fields break through the Sun\u2019s surface \u2013\u00a0emerge\u00a0progressively closer to the equator over the solar cycle.\u00a0\u00a0<\/p>\n \t\t\t\t\t\t\tSOHO peered inside the Sun<\/a><\/p>\n \t\t2. Does the Sun shine steadily?\u00a0<\/p>\n The amount of energy that\u00a0floods out of the Sun\u00a0is\u00a0a fundamental quantity in understanding the impact of solar heating on Earth\u2019s atmosphere and climate. SOHO\u2019s three decades of data, in combination with older measurements, provide unrivalled measurements spanning\u00a0nearly fifty\u00a0years.\u00a0<\/p>\n The total energy output of the Sun changes\u00a0very little\u00a0\u2013 on average, by only 0.06% over the solar cycle. By contrast, the variation\u00a0in\u00a0extreme ultraviolet radiation\u00a0is\u00a0substantial, doubling\u00a0between solar minimum and maximum. Solar\u00a0extreme ultraviolet radiation\u00a0significantly influences the temperature and chemistry in Earth\u2019s upper\u00a0atmosphere, but\u00a0is\u00a0not a direct driver<\/a>\u00a0of the global warming trends\u00a0observed\u00a0near Earth\u2019s surface.\u00a0<\/p>\n \t3. Solar storm monitoring made law <\/p>\n \t\t\t\t\t\t\tCoronal mass ejection on 28 October 2021 <\/a><\/p>\n SOHO has played such a pivotal role in the development of real-time space weather monitoring systems that it was signed into United States law in October 2020.\u00a0\u00a0<\/p>\n The \u2018Promoting Research and Observations of Space Weather to Improve the Forecasting of Tomorrow\u2019\u00a0(PROSWIFT<\/a>)\u00a0act\u00a0SOHO’s\u00a0Large Angle and Spectrometric Coronagraph (LASCO) instrument.\u00a0\u00a0<\/p>\n LASCO\u00a0is a coronagraph, a telescope with a disc masking the\u00a0centre\u00a0of view. By blocking out the direct light coming from the Sun, the instrument can see light from the surrounding atmosphere, called the corona. This allows us to see coronal mass ejections \u2013 large eruptions of solar material and magnetic fields \u2013 as they set off from the Sun, providing up to three days warning of potentially disruptive incoming space weather reaching Earth.<\/p>\n \t4. 5000 comets \u2013 and counting! <\/p>\n \t\t\t\t\t\t\tSOHO’s 5000th comet<\/a><\/p>\n The\u00a0telescope\u2019s\u00a0prowess as a comet hunter was\u00a0unplanned, but\u00a0turned out to be an unexpected success. Thanks to the screening effect of SOHO\u2019s coronagraph, \u2018sungrazer<\/a>\u2019 comets \u2013 those that approach the Sun at\u00a0very close\u00a0distances \u2013 also become visible.\u00a0\u00a0<\/p>\n Not all comets seen by SOHO are sungrazers. For example, it also\u00a0beautifully captured<\/a>\u00a0Comet\u00a0Tsuchinshan\u2013ATLAS,\u00a0also called\u00a0the\u00a0Great\u00a0Comet of 2024, a\u00a0non-periodic comet<\/a>\u00a0from the outer reaches of the Solar System.\u00a0\u00a0<\/p>\n SOHO\u00a0discovered\u00a0its\u00a05000th comet<\/a>\u00a0in March 2024, making it the most prolific comet-discoverer in history.\u00a0Most of these have been\u00a0found\u00a0by citizen scientists worldwide through the\u00a0Sungrazer Project<\/a>. The observations have provided valuable data on the\u00a0movement,\u00a0composition\u00a0and dust production of\u00a0comets.\u00a0<\/p>\n \t5. Enabling future discoveries <\/p>\n SOHO\u2019s success has shaped the next generation of solar observatories, both in terms of their technology and scientific\u00a0objectives, as well as being a role model for open data policies and international collaboration.\u00a0<\/p>\n For example,\u00a0the ESA-led\u00a0Solar Orbiter<\/a>\u00a0mission\u00a0is\u00a0imaging the solar poles from higher latitude and flying much closer to the Sun, with many of its\u00a0instruments\u00a0being\u00a0successors of SOHO’s. Similarly, NASA\u2019s\u00a0Solar Dynamics Observatory<\/a>\u00a0carries improved versions of SOHO\u2019s instruments to continue the legacy that SOHO began in areas of full-disc imaging and helioseismology. Moreover, SOHO\u00a0frequently\u00a0contributes to\u00a0\u2018multipoint\u2019 measurements<\/a>, providing essential context for Solar Orbiter and NASA\u2019s\u00a0Parker Solar Probe<\/a>\u00a0as they fly along their own unique orbits around the Sun.\u00a0\u00a0<\/p>\n Even more recently,\u00a0ESA\u2019s\u00a0Proba-3<\/a>\u00a0took to the skies to\u00a0open up\u00a0new views of the Sun\u2019s faint corona, while the Agency\u2019s upcoming\u00a0Vigil<\/a>\u00a0mission will be the first to\u00a0monitor\u00a0the Sun from the \u2018side\u2019,\u00a0detecting solar storms before they roll into SOHO\u2019s line-of-sight.\u00a0<\/p>\n \u201cSOHO is an all-round shining success, thanks to the dedication of the teams keeping this incredible machine flying,\u201d says Daniel. \u201cIts\u00a0science remains valuable and relevant, serving generations of scientists, and I\u2019m certain that its legacy will continue to guide solar science for decades to come.\u201d\u00a0<\/p>\n Notes for editors\u00a0<\/p>\n![\"\"\/](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2025\/12\/30_years_of_SOHO_imaging_the_Sun_article.png\")
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