SOHO Solar and Heliospheric Observatory (ESA / NASA)
Watching the Sun nonstop since 1995, SOHO helps experts predict solar storms and has found more than 5,000 comets (NASA).
Image: NASA/SDO.
Last reviewed: 3 sources cited
Explain Like I'm 10
- SOHO is a spacecraft that has watched the Sun every day for 30 years.
- It sits in a special spot in space where it can always see the Sun.
- Its pictures help people get ready for solar storms.
The Five W's of SOHO
Who
SOHO is a joint project of ESA and NASA. ESA leads the mission, and NASA contributed three instruments and the launch.
Source: NASA, SOHO
What
An observatory with 12 instruments that studies the Sun from its hot interior to its stormy atmosphere and the A steady stream of charged particles flowing out from the Sun in every direction. Glossary.
Source: ESA, SOHO overview
When
SOHO launched on 2 December 1995. It was meant to work until 1998, and in December 2025 it marked 30 years of operation.
Source: NASA, SOHO
Where
About 1.5 million kilometres (932,000 miles) from Earth, orbiting the L1 point, where it has an uninterrupted view of the Sun.
Source: ESA, SOHO overview
Why
Experts around the world use SOHO images and data to help predict space weather events that affect our planet.
Source: ESA, SOHO overview
Impact Statement
Agency solution · active
SOHO is the most prolific discoverer of comets in history, with more than 5,000 found, over half of all known comets (NASA).
Source: NASA, SOHO
For Further Information: NASA, SOHO
In 1998 contact with SOHO was lost for weeks. A powerful A tool that sends out radio waves and listens for the echoes. From space it can see the ground through clouds, day or night. Glossary signal from Earth found it, and engineers brought it back to work (ESA).
How This Saves People & the Planet
For People
SOHO plays a vital role in forecasting potentially dangerous solar storms (NASA).
Source: NASA, SOHO
For Nature
SOHO has watched two full 11-year solar cycles, showing how our star changes over time (NASA).
Source: NASA, SOHO
Get Involved With SOHO
Want to go deeper? NASA has the full SOHO story.
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