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  • Irish Chronicles Document Links Between Volcanoes and Weather
    A study of over 40,000 written entries in Irish Annals and ice core measurements shows a strong corr...Read more

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    Irish Chronicles Document Links Between Volcanoes and Weather

    A study of over 40,000 written entries in Irish Annals and ice core measurements shows a strong correlation between the occurrence of volcanic eruptions and extreme cold weather in Ireland over a 1200 year period. Data analyzed in this study cover the period from 431 to 1649, during which time up to 48 volcanic eruptions are identified in Greenland ice core records through deposition of volcanic sulfate in annual layers of ice. You can find the study (open access), published on 6 June 2013 in IOP Publishing's journal Environmental Research Letters, at http://iopscience.iop.org/1748-9326/8/2/024035/article. Find out more about how volcanoes can influence climate.
  • EF-5 Tornado in El Reno, Oklahoma Widest Ever Recorded in US
    The EF-5 tornado that hit El Reno, Oklahoma on May 31st was the widest ever recorded in the US, acco...Read more

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    EF-5 Tornado in El Reno, Oklahoma Widest Ever Recorded in US

    The EF-5 tornado that hit El Reno, Oklahoma on May 31st was the widest ever recorded in the US, according to the National Weather Service in Norman Oklahoma. The tornado, which remained on the ground for 40 minutes and reached 2.6 miles across (4.2 km), took the lives of 18 people including storm chasers Tim Samaras, Paul Samaras and Carl Young. For more information on the tornado, visit http://ow.ly/i/2hfDG.
  • 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.
This drawing demonstrates the original orbit of Mars Global Surveyor about Mars. The orbit is shown by the white line. One can see that the original orbit of MGS was far from circular! (This drawing is not to scale. It it merely meant to show the elliptical nature of MGS's original orbit)
Click on image for full size
Image from: NASA/JPL

MGS Original Orbit

Originally, the Mars Global Surveyor entered a highly elliptical orbit around Mars (as shown here). MGS's furthest point of orbit or its apoapsis was ~56,000 kilometers while the periapsis or closest point was only ~150 kilometers above the surface. At this point, it took MGS 45 hours to complete one orbit of Mars.

To get into the near-circular, near-polar, low-altitude orbit necessary to map the surface of Mars, MGS went through a series of aerobraking maneuvers.

After aerobraking was completed in February 1999, the farthest point in the orbit was 506 km with an orbital period of just 1.88 hours. In 2001, the spacecraft's altitude has ranged from about 310 km - 430 km with an orbital period under 2 hours.

Last modified May 11, 2001 by Jennifer Bergman.

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