On this day, two years ago, NASA launched the Interface Region Imaging Spectrograph (IRIS). It was created to study the sun’s chromosphere. And it has a single device on it: an ultraviolet imaging spectrometer. It takes a picture every second. And the pictures have a spatial resolution of 0.3 arcseconds. That’s about 1/6,000 the diameter of the sun.

But the really cool thing about ISIS is that it is in sun-synchronous orbit. That means that it is orbiting the earth from pole to pole. But it precesses at a rate of once per year. Thus, the satellite is always pointing at the sun! I had never even heard of such a thing before. I’ll tell you, those astronomers are very clever!

The results from IRIS are pretty technical. All I can really say is that the sun’s chromosphere appears to have a much more complex structure than previously thought. And different parts quite close together can have drastically different temperatures and pressures. I’m sure it will help us understand better how the sun releases its energy.

The IRIS mission length was supposed to be two years and it is now two years. But you know how NASA is. They are like Scotty from Star Trek, always providing bad estimates so they can look like miracle workers. Although in the case of NASA engineers, they really do seem to work miracles once projects are underway.

Happy birthday IRIS!