by Leah Rose

Created on: December 24, 2008

The sun is one of many factors influencing Earth's climate. Humans have significantly altered the Earth's arable land and oceans during the modern period. The rapid expansion of industrial civilization in the 20th century resulted in significant ecological dislocations. In the late 20th century the hypothesis that carbon dioxide emissions from human activity were magnifying the Earth's natural greenhouse effect became dominant. Today's mainstream global warming hypothesis identifies human activities as the strongest factor influencing Earth's climate. However, data gathered by scientists from around the world indicate temperatures on our planetary neighbors are also rising. These experts attribute Earth's recent warming to an unprecedented increase in solar activity beginning around 1940.

In 1998 the National Aeronautics and Space Administration's (NASA) Hubble Space Telescope and ground-based instruments found that temperatures on Neptune's moon Triton increased dramatically since 1989 when the Voyager space probe last collected temperature data. In the June 25, 1998 issue of the journal Nature James Elliot, an astronomer at the Massachusetts Institute of Technology (MIT) reported that Triton's 5% increase on the absolute temperature scale between 1989 and 1998 would be like Earth warming 22F in nine years. Changes in the reflectivity and heat absorption of the frozen nitrogen surface were the theorized causes of warming on Triton.

In 2002 astronomers announced that Pluto was warming despite its long orbit away from the Sun. Researchers estimated that surface temperatures on Pluto had warmed as much as 3.5F. Researchers from several institutions suggested Pluto's warming might be associated with volcanic activity however it is unclear whether or not there is volcanic activity on the small planet. Researchers also reported that between 1975 and 2000 Mars warmed by as much as 0.65F. At the time researchers were unclear as to the causes of global warming on Mars.

In 2004 the Max Planck Society for the Advancement of Science announced that an international team of scientists had reconstructed solar sunspot activity over the past 11 millennia by analyzing radioactive isotopes in plant fossils. Scientists from the Max Planck Society's Institute for Solar System Research reported in the October 24, 2004 issue of Nature that since 1940 solar sunspot activity increased to an unprecedented level last seen approximately 8,000 years ago. Researchers concluded that along

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