BellaOnline Forums Education Astronomy Watching the Sun for 20 years

On December 2, 1995 SOHO was launched on a planned two-year mission. SOHO is the ESA-NASA Solar and Heliospheric Observatory, and it's still going strong. One and a half million kilometers from Earth, it has watched the Sun for nearly two 11-year solar cycles. It isn't out there just to satisfy the curiosity of academic solar astronomers. It's a vital part of both studying and monitoring the Sun to help predict potentially dangerous solar storms.

Everybody knows what weather is – sun, rain, wind, cloud, etc. But there's no atmosphere in space, so what is space weather? It can endanger astronauts, and in our technological world, a severe solar storm could affect everybody.

And if you're wondering What is space weather? click on the link.

In honor of SOHO's 20th birthday, there was an image contest for people to vote for their favorite SOHO image. The winner shows an enormous eruption of solar material, called a coronal mass ejection, spreading out into space.

It's a composite of two images. The background was taken by SOHO’s coronagraph, an instrument whose disk hides the bright face of the Sun so we can see the faint solar atmosphere. This is the coronal mass ejection. But the Sun at the center was taken by SOHO's Extreme Ultraviolet Imaging Telescope, and superimposed over the occulting disk. Extreme UV is invisible to us, but here it's colorized in red.

Credits: ESA/NASA/SOHO