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Music, Narrator: In 2006 NASA launched the Solar

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TErrestrial RElations Observatory, or STEREO, spacecraft.

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Over the last 4 years, the two spacecraft have slowly made their way along Earth's

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orbit, with STEREO A advancing ahead, and STEREO B falling

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behind. As they've separated, our view of the sun

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has increased. Other satellites near Earth,

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such as SOHO, and now SDO, continue to watch the sun from Earth's

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perspective, while the STEREO spacecraft see increasingly different views.

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Now STEREO A and B are almost exactly opposite each other

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and for the first time in human history, we have a view of the entire sun

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Music

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The sun has a huge

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influence on everyday life, and with our increased reliance on technology, this

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influence just keeps getting stronger. Coronal mass

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ejections and solar flares are the hurricanes of space weather and they have the power to

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disrupt our navigation systems, communications and even electrical grids,

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so it's vital we know when they are coming. Just as protecting our homes

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requires the best possible weather forecast, protecting these systems requires

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the best possible space weather forecast. Sunspots and

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other active regions on the sun can help predict a new round of such space weather, but

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before STEREO we were able to see only one side of the sun at a time;

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we couldn't tell what was starting to form on the far side. Since the sun

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takes about 27 days to rotate once, solar activity had plenty of time

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to build unnoticed. Scientists first began

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to get a sense of the far side with SOHO's Michelson Doppler Imager which worked almost

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like an ultrasound to give a view of the sun's back based on observations of the ripples on

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its front. Now STERE can make direct observations and

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eliminate any uncertainty about activity on the far side of the sun.

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This unprecedented view will last for at least another 8 years as the

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spacecraft slowly continue their journey. They will cross behind the sun,

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and then once again continue to opposite sides of the sun, this time with their position

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reversed. During that time, astronomers will be able to see

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magnetic active regions wherever they form on the sun, so we will know about regions on the far

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side well before any Earth-based observatory can see them.

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The full view of the sun from STEREO and SDO

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coupled with the other spacecraft in NASA's Heliophysics fleet, will help scientists

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understand our dynamic star and give us more time to prepare for the next big

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storm.  Static

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static