Current Events

  • 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 diagram shows a simulated view of the black disk of Venus against the backdrop of the Sun during the Venus transit of June 2004. The yellow arrows show the path of Venus across the face of the Sun throughout the course of the transit.
Click on image for full size
This illustration is original Windows to the Universe artwork created by Randy Russell. The image of the Sun is courtesy SOHO (ESA & NASA); information on the apparent size and path of Venus courtesy Fred Espenak, NASA's GSFC.

Transits of Venus

The planet Venus periodically passes directly between Earth and the Sun. This event, which is somewhat similar to a solar eclipse, is called a transit of Venus. Viewed from Earth, Venus and Mercury are the only two planets that can transit the Sun.

Transits of Venus are very rare events. The last Venus transit was in 1882. The next one will be on June 8, 2004. Venus transits come in pairs separated by eight years, with more than a century between successive pairs. The second in the upcoming pair will be on June 6, 2012.

At least some part of the 2004 transit, which will last about six hours, will be visible from most places on Earth. NASA has a web site that provides information about viewing this transit.

Transits of Venus played an important role in the history of astronomy. Astronomers in the 1700s and 1800s used measurements of angles during Venus transits to determine the length of the Astronomical Unit (AU), the distance from Earth to the Sun.

Last modified May 24, 2004 by Randy Russell.

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Transit

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An Overview of the Interior and Surface of Venus

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Transits of Venus

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The Poles of Venus

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