Although studies of the sun, the most indispensable object in the nearby universe, date back at least as far as two Chinese astronomers Hsi and Ho "... who were too drunk to predict the an eclipse, possibly even that of October, 22, 2134 BC. and were beheaded as a result," (according to the 1997 book on the solar corona by Leon Golub and Jay Passachoff), it was only with the 19th century and the development of photography and spectroscopy, combined with proper observation and record-keeping, that genuine scientific solar research could begin.
On September 1st, 1859, a British astronomer observed and recorded for the first time a major solar flare, now known as the "Carrington Event" . As the radiation from the storm hit the Earth it knocked out telegraphs, the world's first electromagnetic-based communications system. Scientists think that this may be the most powerful blast of solar energy to have hit the Earth in modern times. A similar blast today would probably produce catastrophic results.
In the 21st century, the study of the sun should be a major priority. Its radiation can, with little or no warning, disrupt our electronic civilization. In 1998 a solar storm knocked out a communications satellite and rendered millions of pagers all over America, useless. In 1989 a similar storm destroyed a transformer and blacked out most of Quebec. Since then, our dependence on delicate digital systems has increased and few of them are hardened against sudden spikes in solar radiation, (let alone against Electromagnetic Pulse - EMP, but that is another story). Even moderate solar activity can have an effect on our lives such as degrading the accuracy of the signals from the GPS satellites or the power-output from communications satellites.
How bad can it get?
Answering that question is a key goal of the Solar Dynamics Observatory [SDO] NASA launched in February 2010 to study the variability of the sun and just now showing its first results. SDO is equipped with cameras that will be able to take IMAX-quality images of solar explosions. It also has sensors that can look deep inside the sun to reveal the inner workings of the sun's magnetic dynamo, the root of all solar activity. SDO's Helioseismic and magnetic imager will allow "Scientists to make ultrasound images of the Sun and to study active regions in a way similar to watching sand shift in a desert dune."
The most important feature of NASA's SDO mission is the Solar Sentinel program, which will send a series of satellites that will give us a permanent three-dimensional near-real-time vision of the Sun. These spacecraft will actually lead the way towards a move from gathering data for science and gathering data for what might be termed -Solar System Wide Weather forecasting.
There is already a significant space-weather community, but their work is only of interest to satellite operators and a few other specialists. As the quality of the Solar Physics data grows and as our need to protect an increasingly vulnerable electronic civilization becomes vital, programs like LWS, are supported by NASA as part of its science mission. But at some point soon, perhaps during the 2013 Solar Maximum, when it is predicted that the Sun's activity will peak, they will be seen as an essential public resource.
The other main instruments are the Atmospheric Imaging Assembly, which operates in 10-wavelengths bands, and the Extreme Ultraviolet Variability Experiment, which "measures fluctuations in the Sun's radiant emissions." Taken together, these sensors will, over the planned five year length of the mission, provide researchers with an unprecedented flow of data that will almost certainly revolutionize our understand of the Sun. In turn this will transform our understanding of other stars and, more important for us Earthlings, allow us to understand better the way Solar activity impacts the Earth's climate.
Almost all Solar scientists have tried to stay away from the political fights over Global Warming and Climate Change. Most expert skeptics and believers tend to dismiss the impact of the Sun on the climate. They prefer to focus on either water vapor or CO2 as the main driving forces. Yet it is hard to see how, at the margins anyway, such a power can fail to have an impact. If anyone does a serious study of this possibility using data from SDO, reliable results cannot be expected for at least five, or more likely ten, years -- a good example of the disconnect between the time required for sound science and the timeframe in which politicians operate.
SDO is just one part of an important, ongoing NASA program called Living With a Star (LWS). Previous missions include the joint ESA/ NASA Solar and Heliophysics Observatory; launched in 1995 and, in spite of many onboard failures, still operating. A more recent mission is the Solar Terrestrial Relations Observatory Mission, which consists of a pair of spacecraft that provide a view of the Sun in almost three dimensions. Together these missions have radically improved our knowledge of the Sun and laid the basis for the giant steps in understanding that are to be expected from SDO.
