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Science Friday: Shark Teeth Have Built-In Toothpaste | What if we had a planet instead of a Moon?

Submitted by Tjadendevries on Fri, 07/27/2012 - 11:58pm

The video has little to do with the article, other than being about a shark, but, it's one of the most frightening scenes in Jaws, and the ironic thing is there's no shark anywhere

Shark Teeth Have Built-In Toothpaste

The dense, flat, crushing teeth of sharks contain fluoride keeping their impressive mouths free of cavities and other problems.

    THE GIST
    • The outside of shark teeth is made up of fluoride, the active component of most toothpaste.
    • Although human teeth are covered in a different mineral, both shark and human teeth are equally hard.
    • Sharks never get cavities, and are able to replace their teeth multiple times throughout their lives.

    An in-depth look at shark teeth has found that they contain fluoride, the active ingredient of most toothpaste and dental care mouthwashes.

    It helps to explain why sharks are so effective at either tearing or cutting prey. Their teeth are perfectly designed for such tasks, never suffering from cavities, according to the study, recently published in the Journal of Structural Biology,

    [...]

http://news.discovery.com/animals/shark-teeth-flouride-120725.html

Link to the source of the picture

What if we had a planet instead of a Moon?

    [...]

    At a distance of about 240,000 miles, the Moon occupies a space in the night sky about half a degree wide. By sheer coincidence, this is almost exactly the same size the sun appears, which is why we occasionally get total solar eclipses. (We don't get a total eclipse every time the Moon passes in front of the sun because the Moon is sometimes a little closer to the Earth and sometimes a little further away, so it will cover more or less of the sun during any eclipse.)

    But it's interesting to imagine what the night sky might look like if one of the Solar System's planets were to replace our moon. (We'd have to ignore things like tides and gravitation, but that's the advantage of doing things in the mind's eye.) So what would we see if we were to replace the moon with Mars? The red planet is almost exactly twice the size of the Moon, so it would appear twice as big in the Earth's sky. It would be easy to see with the naked eye details on the surface of the planet that were previously visible only through telescopes. You could watch the ice caps grow and shrink during the changing seasons, see dust storms form and move across the planet and make out features like Vallis Marineris and Olympus Mons.

    [...]

More comparisons at the link

http://io9.com/5929076/what-if-we-had-a-planet-instead-of-a-moon