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PICTURE OF THE DAY 6/13/02 http://science.nasa.gov/ppod/

Submitted by Arthur - N1ORC

Space Station Science
Picture of the Day   

 June 13, 2003

Photo credit: The crew of ISS Expedition 7, NASA

 Listen to this story via streaming audio, a downloadable file, or get

June 13, 2003: Four hundred years ago the makeup of our solar system was
a matter of intense debate. Was Earth at the center of everything? Or
the Sun? Astronomers knew of six planets including our own. Why six? And
what determined their spacing? No one knew.

In 1595, Johannes Kepler had a beautiful idea. He was fascinated by the
five "perfect solids," also known as Platonic solids: the tetrahedron,
the cube, the octahedron, the dodecahedron and the icosahedron (pictured
right). Each is made of only one kind of regular polygon--a triangle, a
square or a pentagon--hence their "perfection." Kepler realized that
these five solids nestled one inside another defined the supporting
structures for six circular orbits. Planetary orbits! "The intense
pleasure I have received from this discovery can never be told in
words," wrote Kepler.

Too bad it was wrong. Planetary orbits are not circular--a fact later
discovered by Kepler himself. Now we know there are nine planets, not
six, and the Platonic solids have nothing to do with the architecture of
our solar system.

Nevertheless, 3D solids made of squares and triangles and pentagons
continue to fascinate scientists and explorers. Witness today's picture:
a hebesphenomegacorona onboard the International Space Station.

This solid has 21 faces, three squares and 18 triangles. It is one of
the three-dimensional shapes called "Johnson solids" you can make by
mixing different kinds of regular polygons. In 1969, mathematician
Viktor Zalgaller proved there were only 92 Johnson solids, and he gave
each one a fanciful name: e.g., square dipyramid, pentagonal
orthocupolarontunda, gyrobifastigium, snub disphenoid, and
hebesphenomegacorona. (A fun word game: try to use one of these names in
everyday conversation.)

What's a hebesphenomegacorona doing onboard the ISS? We're not sure. It
was made by Ed Lu or Yuri Malenchenko using paper and tape. One of them
fixed it to the top of the Destiny Lab window and took its picture with
the cloudy Pacific Ocean in the background.

Were they testing Zalgaller's proof in microgravity? Passing the time on
a Saturday morning? Building models of weird solar systems? Maybe they
were just playing word games.

Ed: "Yuri, I think I just saw a hebesphenomegacorona in the Destiny

Yuri: "Are you sure? It looked more like a snub disphenoid to me...."

Today's picture, ISS007-E-05280, was taken on May 15, 2003. Additional
images taken by astronauts and cosmonauts may be viewed at the NASA-JSC
Gateway to Astronaut Photography of Earth.

Credits & Contacts
Author: Dr. Tony Phillips 
Responsible NASA official: Ron Koczor Production Editor: Dr. Tony
Curator: Bryan Walls 
Media Relations: Catherine Watson

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