Venus Transit Casts Earth Shadow

This image is from a multi-instrument movie of the October – November 2003 solar storms. The movie combines false-color views from three instruments on board the Solar and Heliospheric Observatory (SOHO) spacecraft. Credit:SOHO/ Tom Bridgman/ESA

Scientists using measurements from NASA’s Solar Radiation and Climate Experiment (SORCE) satellite have discovered that Venus and sunspots have something in common: they both block some of the sun’s energy going to Earth.





Spectacular science from the solar observatory, or SOHO, gives the most spectacular view of solar events. SOHO is located 1.5 million kilometers (one million miles) from Earth. It orbits around the First Lagrangian point, where the combined gravity of the Earth and the sun keep SOHO in an orbit locked to the sun-Earth line.


Rottman said, "Something very different was happening during the seventeenth century, and it produced a much more permanent change in the sun’s energy output at that time." Today, the large sunspots are surrounded by bright areas called "faculae." Faculae more than compensate for the decrease in sunlight from sunspots, and provide a net increase in sunlight when averaged over a few weeks.

Solar flares issue strong electromagnetic bursts.


"The SORCE satellite instruments provide measurements of unprecedented accuracy, so the sun’s energy output is known with great precision, and precise knowledge of variations in the sun’s energy input to Earth is a necessary prerequisite to understanding Earth’s changing climate," said Robert F. Cahalan, SORCE Project Scientist and Head of the Climate and Radiation Branch at NASA’s Goddard Space Flight Center, Greenbelt, Md.

The SORCE measurements provide today’s atmospheric and climate scientists with essential information on the sun’s energy input to the Earth. These measurements also will be valuable to future scientists, who will be relating their view of the world back to conditions existing today. Likewise Galileo’s findings about the sun almost 400 years ago have increased in value as understanding of the sun and its importance for Earth has advanced.

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