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Space Station Science

Picture of the Day

June 13, 2003

Hebesphenomegacorona
Photo credit: The crew of ISS Expedition 7, NASA

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. 

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
Lab."

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 Phillips 
Curator: Bryan Walls 
Media Relations: Catherine Watson

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