Keystone Weekly
volume 4, issue 29        May 12, 2003

This week's Key Points: *Web Pick of the Week* and *Awesome Science!*
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Science officer Don Pettit and his Expedition 6 crewmates onboard the International Space Station have been sending extraordinary pictures back to Earth. Some show breathtaking views of the sky through the station's windows; others highlight ongoing scientific research in physics and biology. The website above was developed expressly for the purpose of sharing these images, and every weekday, the International Space Station crew and NASA staff provides a new photo.

The photos themselves are worth a look, but if you'd like to dive a little deeper, click on the links sprinkled throughout the explanation of the photo to learn more about the Space Station, objects in space, the mission, and whatever the subject of the image is on that day.

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Researchers from Duke University have made a startling discovery: there's more to certain species of butterflies than meets the eye. These scientists report that at least one butterfly species, Heliconius cydno, has patterns on its wings that reflect polarized light, invisible to the human eye but visible to other butterflies, and attractive to potential mates.

Light bouncing off this species' wings was being polarized, whereas a very similar species exhibited no signs of polarization. The article explains polarization: "Light waves can be thought of as vibrating in different directions as they beam from the sun. When bouncing off some objects, light can become polarized, meaning that all the light from the object is aligned, vibrating in the same direction." The researchers have found that this polarization sends a distinct signal to other butterflies.

This is not the first instance of insects using polarized light; bees and ants can use patterns of polarized light in the sky, which change over the course of a day, to help them navigate.

See the link above for details and photos. (The site requires free registration.)

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This material is based upon work supported by the National Science Foundation under Grant No. 9819641.
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

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