* Astronomy

First Light for the Solar Dynamics Observatory

At a press conference today in Washington DC, researchers unveiled "First Light" images from NASA's Solar Dynamics Observatory, a space telescope designed to study the sun.
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Magnetic 'ropes' tie down solar eruptions

Over the last century, astronomers have become very aware of how just dynamic the Sun really is. One of the most dramatic manifestations of this is a coronal mass ejection (CME) where billions of tons of matter is thrown into space. If a CME reaches the Earth it creates inclement 'space weather' that can disrupt communications, power grids and the delicate systems on orbiting satellites. This potential damage means there is a keen interest in understanding exactly what triggers a CME outburst.
Now a team of researchers from University College London (UCL) have used data from the Hinode spacecraft, revealing new details of the formation of an immense magnetic structure that erupted to produce a CME on the 7th December 2007. Lead researcher Dr Lucie Green will present their results on Monday 12th April at the RAS National Astronomy Meeting in Glasgow.
The Sun's behaviour is shaped by the presence of magnetic fields that thread through the solar atmosphere. The magnetic fields may take on different shapes from uniform arches to coherent bundles of field lines known as 'flux ropes'. Understanding the exact structure of magnetic fields is a crucial part of the effort to determine how the fields evolve and the role they play in solar eruptions. In particular, flux ropes are thought to play a vital role in the CME process, having been frequently detected in interplanetary space as CMEs reach the vicinity of the Earth.

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During the recent solar activity minimum, the Sun was the dimmest X-ray star within 23 light years of its neighbourhood - this is suggested by measurements collected by scientists at the Space Research Centre (SRC) of the Polish Academy of Sciences.
The measurements were made using the Polish-built super-sensitive instrument SphinX located aboard the solar orbiting observatory CORONAS-Photon.
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Sun's long slumber a wake-up call to solar scientists

The sun once was considered a steady star without change. The sun's energy output, as measured above the earth's atmosphere, was called "the solar constant." As astronomers studied the sun, they realized that this notion wasn't quite correct. They found that the solar output varied slightly by a few tenths of a percent. The amount rose when the sun was active (solar maximum) and declined when it was quiet (solar minimum).
Solar astronomers counted the number of dark spots on the disk of the sun to gauge the sun's activity. In 1843, a German amateur astronomer, Samuel H. Schwabe, realised that the number of sunspots varied over time. The average cycle goes from a few to many spots and back in about 11 years. A few years later, Rudolph Wolf, a Swiss astronomer, confirmed the roughly 11-year cycle. He numbered the sun spot cycles beginning in 1755 as Cycle Number One. In 1852, four astronomers realised that the activity of the sun and the geomagnetic activity on earth were interrelated. That was the beginning of the sun-earth connection and space weather.
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