Friday, November 2, 2007
Thursday, November 1, 2007
Colored Scanning Electron Micrograph (SEM) of scales from the wingof a peacock butterfly (Inachis o). These scales have an intricatedesign and overlap like the tiles on a roof. They allow heat and lightto enter and also help the butterfly to retain warmth. They may alsobe very colorful. Magnification: 750 X.
Colored Scanning Electron Micrograph (SEM) of nylon hooks and loopsin Velcro material. Used as a common fastener on clothes and shoes,Velcro is a nylon material formed into two different structures: one a nail-head-like surface, and the other a smooth surface made up of a seriesof loops. The loops are loosely woven strands among an otherwisetight weave. When the two surfaces are brought together they form astrong bond, but can still be pulled apart. Magnification: 50 X.
Colored scanning electron micrograph (SEM) of a cross-section of a human capillary, showing the red blood cells (red discs) it contains.The smallest type of blood vessel, capillaries pervade body tissue,forming a fine network that links veins and arteries.They have permeable walls that allow the exchange of gases andnutrients between the blood and tissue. Also known as erythrocytes,red blood cells transport oxygen to the tissue and carbon dioxideback to the lungs. Magnification: 2.600 X
Explanation: Today a team of NASA and Stanford scientists announced the discovery of strong circumstantial evidence that microscopic life once existed on Mars. Dr. David McKay, Dr. Everett Gibson, and Kathie Thomas-Keprta of Lockheed-Martin, all from (NASA /JSC), and Dr. Richard Zare (Stanford) have led a team that has found chemical evidence for past life on Mars - including what they interpret as possible microscopic fossil remains (tube-like structures pictured above) - in a meteorite thought to have originated on Mars. A small fraction of the many meteorites that fall to Earth from space have composition similar to the Martian surface. Many scientists believe that these meteorites are indeed Martian rocks that have been catapulted into space during a catastrophic event on Mars, such as an asteroid impact. The escaped rocks would then circle the inner Solar System, some of them falling to Earth. The meteorite containing the evidence landed on Earth 13,000 years ago, but may indicate a life-form that existed on Mars billions of years ago. The team's findings will be published in the August 16 issue of Science Magazine. Even skeptical scientists look forward to future research confirming or refuting these exciting claims.
The particle in this scanning electron microscope image is approximately 8 micrometers (0.008 mm) in diameter. The outer shell is rich in silicon and aluminum. The inner portion contains more magnesium and iron. The small raised areas on the surface are titanium-aluminum-iron-rich crystals of a mineral called spinel. The holes in the background are part of the filter paper that the particle was collected on.