Using the measurements of one of the solar radiation research satellites, NASA discovered that the planet Venus and sunspots have a central feature in common: blocking part of the solar energy coming from the sun to the Earth.
Sunspots
Using data from NASA's SOCRE satellite, scientists observed that when Venus passed between the Sun and the Sun on June 8, the amount of light reaching the Sun was reduced by a tenth of a percent.
"Because of its distance from Earth, Venus appeared to be the size of a sunspot," says Gary Rothman, principal investigator and scientist at the Laboratory for Space and Atmospheric Physics [LASP], at the University of Colorado at Boulder.
The SORCE research satellite team also saw similar reductions in solar energy reaching the Sun during the October 2003 spot activity.
In October 2003, sunlight reaching the Earth was reduced by 0.3 percent of normal due to giant sunspot groups moving across the Sun's surface.
"This is an unprecedented reduction in the amount of sunlight reaching us, and is comparable to the reduction estimated to have occurred in the seventeenth century," says Rothman. The reduction lasted for almost fifty years, and was probably linked to the exceptional cold that prevailed in Europe at that time, between the years 1400 and 1700, also called the "Short Ice Age".
Solar conditions during the "Short Ice Age" were quite different, as there were no sunspots.
The astronomers of the period, such as Galileo, kept many observations and records regarding the sun, both before and after the period, in which you can find 50 sunspots in an average of 30 years, a relatively small number.
The large number of spots in October-November 2003 indicated that the sun was very active, and indeed at that time many volcanic eruptions happened.
A "scanner" saw these eruptions in infrared. The eruptions were accompanied by large sunspots, which produced a decrease of 0.3 percent of the outgoing solar energy.
At the same time, a "scanner" collected energy from all wavelengths, something that had never been done before.
"The instruments on the Sork satellite provide unprecedented precise measurements, so that the energy output of the Sun is known with great precision, and knowledge of changes in the energy coming from the Sun to the Earth is a prerequisite for understanding the Earth's climate," said Robert P. Callahan, Project Scientist and Head The Climate and Radiation Branch at NASA's Goddard Air Force Base in Greenbelt, Maryland.
The measurements of the "scanner" give today's climate and atmospheric scientists information about the solar energy reaching the Earth.
These measurements will be valuable to the scientists of the future, who will relate the appearance of their world to the conditions prevailing today. In addition, Galileo's findings about the sun from 400 years ago enriched the understanding of scientists today about the sun, and its importance in the eyes of man increased as a result.
