14 DAY TRIAL // The last word that anyone could associate with the Sun is calm, given the brutal and savage nature of the events taking place on and within the star. It is, after all, just a large, constantly-exploding fireball, which emits energy in various shapes and forms. Still, astronomers have recently discovered that, in spite of the vast array of violent transformations taking place on the object daily, its size continues to remain surprisingly constant. The trend has been maintained over the past years as well, and scientists are puzzled at this occurrence, Space reports.
Statistical analysis of the star reveal the fact that its diameter, for example, changed by less than one part per million over the past dozen years or so. The Sun is some 932,057 miles (1,500,000 kilometers) across today, and its size is basically the same as it was during the previous solar cycle. “The Sun is remarkably constant. We're measuring that the diameter changes by less than a kilometer (0.62 miles). This constancy is baffling, given the violence of the changes we see every day on the sun's surface and the fluctuations that take place over an 11-year solar cycle,” explains University of Hawaii Institute for Astronomy associate director Jeff Kuhn, who was also the lead researcher on the investigation.
He adds that additional discrepancies have been discovered between measurements of the Sun taken from Earth and other studies conducted from orbit. There are not very many explanations available for why these differences exist, the expert says. “What this really means is that, if we believe the ground measurements, then what we're seeing is long-term fluctuations in the Earth's atmosphere. The Sun is influencing the atmosphere of the Earth in very significant ways,” Kuhn believes.
At this point, a large number of research groups around the world are working on determining precisely how our star influences Earth's climate. According to some, the correlations may run deeper than anyone initially estimated, and it may turn our that using space-based solar measurements as a reference for Earth-based studies could give experts a way forward in this field. “We can't predict the climate on Earth until we understand these changes on the sun,” Kuhn believes.
The initial set of experiments that led to the discovery was conducted using the American space agency's Solar and Heliospheric Observatory (SOHO) spacecraft, which is a pioneer and a veteran of studying the star. Still, the group plans to carry on with its research, and to use the recently-launched NASA Solar Dynamics Observatory (SDO) to conduct a similar series of investigation. Once completed, in 2017, the Hawaii- based Advanced Technology Solar Telescope (ATST) will allow for more detailed data to be obtained from Earth as well.
“To be able to predict what the sun will do, we need both the big picture and the details. Just as powerful hurricanes on Earth start as a gentle breeze, the analogs of terrestrial storms on the Sun start as small kinks on the Sun's magnetic field,” Kuhn explains, saying that the ATST will be able to trace minute changes on the surface of the star in great detail.