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  • Atmospheric CO2 Level Tops 400 ppm
    During the week of May 13th, the CO2 level at the Mauna Loa Observatory in Hawaii topped 400 ppm rep...Read more

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    Atmospheric CO2 Level Tops 400 ppm

    During the week of May 13th, the CO2 level at the Mauna Loa Observatory in Hawaii topped 400 ppm repeatedly. Daily levels of CO2 can vary due to weather, and there are seasonal trends as well. The level of atmospheric greenhouse gases continues to increase, now over 120 ppm since the Industrial Revolution began. For more on the Keeling Curve, see http://keelingcurve.ucsd.edu/. Find out more about greenhouse gases and warming.
  • Massive Tornado Outbreak on Tornado Alley
    The week of May 19 brings dozens of tornadoes to Tornado Alley in the states of Oklahoma, Kansas, Io...Read more

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    Massive Tornado Outbreak on Tornado Alley

    The week of May 19 brings dozens of tornadoes to Tornado Alley in the states of Oklahoma, Kansas, Iowa, Illinois and Missouri. On May 20th, a massive tornado struck Moore, Oklahoma, devastating communities - destroying over 100 homes and hitting two elementary schools and a hospital - with many casualties and deaths. Our thoughts are with our friends and colleagues suffering from these storms. For more on the May 20th storms, see the NOAA Storm Prediction Center Storm Report.
  • Kansas Legislator Proposes Bill to Outlaw Sustainability Education
    A bill has been introduced in the Kansas legislature this week that would prohibit the promotion of ...Read more

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    Kansas Legislator Proposes Bill to Outlaw Sustainability Education

    A bill has been introduced in the Kansas legislature this week that would prohibit the promotion of sustainability. Here is a link to the one-page bill: http://www.kslegislature.org/li/b2013_14/measures/documents/hb2366_00_0000.pdf. See report on Bloomberg News.
This picture shows the surface of Phoebe. There are many large craters on Phoebe's surface. The picture was taken by the Cassini spacecraft in 2004.
Click on image for full size
Image courtesy of NASA/JPL/Space Science Institute.

Phoebe

Phoebe is the name of a medium-sized moon of Saturn. An American astronomer named William Henry Pickering discovered Phoebe in 1898. The name "Phoebe" comes from Greek mythology. In the Greek myths, Phoebe was the daughter of Uranus and Gaia and the grandmother of Apollo and Artemis.

Phoebe has a diameter of 220 km (137 miles). It is the ninth largest of Saturn's moons. The surface of Phoebe is very dark. That is strange. Most of Saturn's moons have bright surfaces. Its dark surface isn't the only strange thing about Phoebe.

Phoebe's orbit around Saturn is also odd. Phoebe orbits much further from Saturn than any of the other medium-sized moons. Also, Phoebe orbits backwards! It moves around Saturn in the opposite direction of most of the other moons.

Why is Phoebe so strange? Many astronomers think Phoebe used to be an asteroid or Kuiper Belt Object. They think Saturn's strong gravity captured Phoebe sometime long ago.

Astronomers want to learn more about Phoebe. Right now, our only pictures of Phoebe are very fuzzy. They were made by Voyager 2 in 1981. Soon we should have much better pictures! The Cassini spacecraft will fly very close past Phoebe on June 11, 2004.

Last modified October 8, 2009 by Randy Russell.

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