The European Space Agency (ESA) is Europe’s gateway to space. Its mission is to shape the development of Europe’s space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world.
Find out more about space activities in our 23 Member States, and understand how ESA works together with their national agencies, institutions and organisations.
Exploring our Solar System and unlocking the secrets of the Universe
Go to topicProtecting life and infrastructure on Earth and in orbit
Go to topicUsing space to benefit citizens and meet future challenges on Earth
Go to topicMaking space accessible and developing the technologies for the future
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The Sun is filled with many kinds of sound waves caused by the boiling motion of gas in its surface layers. SOHO’s Michelson Doppler Imager (MDI) instrument traces these ‘sound waves’ reverberating through the Sun to build up a picture of the far side. The MDI uses a far-side imaging method which compares the sound waves that emanate from each small region on the far side, with what was expected to arrive at that small region from waves that originated on the front side.