ACROSS THE UNIVERSE (4)- The Sun as You've Never Seen It Before

17 May 2007

Published on the New York Times web site - MARCH 14, 2007.

By BRIAN MAY

On the Internet right now, just one click away, you can find a wonderful movie made by NASA of the recent eclipse of the Moon past the Sun, but it is something very special. This version is viewed not from the Earth but from one of NASA's twin Solar Terrestrial Relations Observatories, satellites that recently were launched to study the Sun from space. From this vantage point, the Moon appears much too small to cover the Sun ? so what we see is a transit of the Moon across the sun's face.

I suddenly realized that this wonderful movie of the Moon traveling across the face of the Sun provides a perfect opportunity to compose celestial stereo pictures. NASA's experiment in three-dimensional Sun photography is very clever; these chaps have launched two satellites, both of which move in orbits, not around the Earth, but around the Sun. Their orbits are almost identical to the orbit of our Earth around the Sun, but one space vehicle is positioned just ahead of the Earth, and one just behind it. The plan is for them to take pictures of the Sun simultaneously, from two different angles, so that the two photographs will make a stereo pair with a very long baseline, enabling scientists to study the Sun's surface in three dimensions. Ingenious!

At the moment the two satellites are not quite ready to function completely; this movie was photographed from one satellite only, called Stereo-B. But because the Moon was moving during the time this movie was filmed, we can make a nice stereo effect by choosing two frames close to each other in time, and mounting them as a pair. I did it myself (with glorious Photoshop, of course) using stills I captured from the movie on the NASA site. In this picture, the Moon looks closer to us than the Sun, because we have given it artificial parallax, fooling our eyes into seeing it standing out from the surface of the Sun.

Look at the picture below. At first, it just looks like two eyeballs! But if you stare through the picture toward the wall behind your computer screen, and let the two balls 'swim' together (as you do when looking at those Stare-eo images you get on posters), suddenly you will see, in the center, a nice black Moon standing out in front of a wonderful (though quite flat) Sun. Go on, try it!

(Alternatively, print out the photo pairs so that the distance between the centers of the balls is about 2.5 inches. Then view the result in a stereo viewer: for instance, the Holmes viewers, made around 1900, which are so often found in antique fairs and bric-a-brac shops.) This is fun. Although not very real.

What is really fabulous is the result we get when we use the fact that the Sun is slowly turning during the movie, giving us a succession of viewpoints from different angles, exactly what the experiment is designed to achieve with the two satellites. The pair I made to illustrate this is below. Once I had this put together, I could not stop looking at it. It's not perfect, because the surface of the Sun is a seething mass of turbulence, so some of the details changed a little between the live capture of these two views. (I used one from the beginning of the sequence and one from the end.) But on the whole, the major features are changed only slightly, so the result is a three-dimensional image of the Sun that is perhaps the best I have ever seen. I cannot imagine that I am the first to realize this, but I?d be very interested to know if anyone from NASA has made this stunning stereo.

Meanwhile, enjoy this, possibly the first ever 3-D view of the Sun in ultraviolet from space. My thanks to NASA for being so generous with their images. And giving us yet another stupendous treat.

Cheers!

Editor’s note: Earlier versions of this column incorrectly described the subject of the first set of stereo photos as a recent lunar eclipse. They are photos of the Moon in transit past the Sun.

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