Current Events

  • 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.
  • Earth's Center Is 1,000 Degrees Hotter Than Previously Thought, Synchrotron X-Ray Experiment Shows
    Scientists have determined the temperature near the Earth’s center to be 6000 degrees Celsius, 1000 ...Read more

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    Earth's Center Is 1,000 Degrees Hotter Than Previously Thought, Synchrotron X-Ray Experiment Shows

    Scientists have determined the temperature near the Earth’s center to be 6000 degrees Celsius, 1000 degrees hotter than in a previous experiment run 20 years ago. These measurements confirm geophysical models that the temperature difference between the solid core and the mantle above, must be at least 1500 degrees to explain why the Earth has a magnetic field. For more information about this study, see the press release from the European Synchrotron Radiation Facility.
  • Ocean Volcanic Rocks Contain Samples of Recycled Crust
    Scientists have long believed that lava erupted from certain oceanic volcanoes contains materials fr...Read more

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    Ocean Volcanic Rocks Contain Samples of Recycled Crust

    Scientists have long believed that lava erupted from certain oceanic volcanoes contains materials from the early Earth’s crust. But decisive evidence for this phenomenon has proven elusive. New research from a team including Carnegie’s Erik Hauri demonstrates that oceanic volcanic rocks contain samples of recycled crust dating back to the Archean era 2.5 billion years ago. Their work is published in Nature. Oceanic crust sinks into the Earth’s mantle at so-called subduction zones, where two plates come together. Much of what happens to the crust during this journey is unknown. Model-dependent studies for how long subducted material can exist in the mantle are uncertain and evidence of very old crust returning to Earth’s surface via upwellings of magma has not been found until now. For more information about these results, see the press release from the Carnegie Institution.
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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History of Venus Transits

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Venus Transit in June 2004

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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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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF