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Nov 28, 2005 - The Solar and Heliospheric Observatory (SOHO) is celebrating its 10th anniversary of operations on December 2nd, 2005. Over the course of these 10 years, SOHO has revealed the nature of the Sun's atmosphere, the links between its magnetic fields and coronal mass ejections, and even discovered more than 1,000 comets. Scientists even figured out how to use SOHO to probe the far side of the Sun.
Oct 6, 2005 - This amazing image is of a sunspot three times the size of the Earth. The photograph was taken using the National Science Foundation's Dunn Solar Telescope at Sunspot, NM, which was recently upgraded with an adaptive optics system. The Dunn telescope has a flexible mirror which can be deformed 130 times a second to compensate for atmospheric distortion. This image was made with 80 individual photographs combined together.
Sep 16, 2005 - We should be near the beginning of the Sun's solar minimum period; the point on its 11-year cycle when there's usually very little activity on its surface. Well, someone should have informed the Sun, because it's as active now as it can be during its solar maximum. Sunspot numbers have been declining as predicted, but this hasn't decreased the number of solar flares and coronal mass ejections. So, what's going on? Astronomers don't really know. Unfortunately we've only got about 25 years of satellite data to look back at to see the patterns.
Aug 17, 2005 - When astronauts will be spending more time in space, it'll be helpful to know when there'll be clear "space weather", to minimize their exposure to dangerous amounts of radiation. NASA scientists have developed a better understanding of the underlying causes of solar flares, and think they can now predict times for "clear skies". Areas likely to explode as flares happen when magnetic fields of different alignments merge together on the Sun's surface. Electrical currents must then build up for several hours before a flare erupts.
Aug 12, 2005 - New research from the University of California, San Diego suggests that the cloud of gas and dust that would eventually turn into the Sun was already hot and glowing. The ultraviolet radiation blazing off this protosun played a big part in chemically shaping the early Solar System, including many of the organic compounds that make up life on Earth. The scientists detected it by finding evidence of high-energy solar wind in ancient meteorites.
Aug 3, 2005 - Astronomers with the European Space Agency have watched the entire lifecycle of a solar storm using the SOHO and Cluster spacecraft. SOHO detected a large solar flare on the Sun, and then the resulting coronal mass ejection passed the Earth and the 4 Cluster spacecraft. Scientists have speculated that these ejections change shape as they travel from the Sun to the Earth, but the Cluster spacecraft found just the opposite, that its magnetic field stayed the same for the journey.
Jul 28, 2005 - Take your estimate for the amount of neon in a star, and triple it. At least, that's what a team of astronomers using the Chandra X-Ray Observatory have concluded. They performed a detailed survey of 21 nearby sun-like stars within a distance of 400 light-years from Earth, and found they all contained an average of 3X the neon traditionally predicted for our Sun. Neon is difficult to find in stars because it doesn't give off any light in the visible spectrum. But when heated to millions of degrees, for example, in a star, this elusive element blazes in the X-ray spectrum.
May 24, 2005 - One of the most intense bursts of solar radiation in more than 50 years happened in mid-January this year, and scientists are still mulling over the implications for current space weather theories. Another interesting aspect of this flare is how quickly it traveled through the solar system. Normally a proton shower associated with a flare takes several hours to reach the Earth, but we were hit with the first particles in just 15 minutes. This could have important implications for future space weather warning systems, to keep astronauts safe from solar storms.
May 20, 2005 - Researchers have discovered that the structure of the Sun's lower atmosphere, or chromosphere, can be used to predict the speed and intensity of solar winds - the stream of electrified gas constantly blowing off the Sun. This was unexpected, because the solar wind comes from the corona, or outer layer, while the chromosphere is much deeper into the Sun. By learning how to predict the strength and speed of the solar wind, scientists will be able to protect electrical equipment, satellites and space explorers.
May 11, 2005 - Usually it's the biggest things that get the news, but an international team of researchers have demonstrated that the tiny might be just as important. They spotted the smallest coronal mass ejection (CME) ever seen on the surface of the Sun, produced from a region not much bigger than the Earth. This sounds big, but it's a fraction of the size of those huge CMEs we normally see in pictures of the Sun. Amazingly, the magnetic field lines in this pint-sized CME were 10x more twisted than their larger cousins.
May 6, 2005 - Our star goes through an 11-year cycle of solar activity. At the recent height of the cycle, the Sun blasted off some of the most powerful flares and coronal mass ejections ever seen. And during the minimum, due in 2006, it's supposed to be calm, right? Well, not exactly. Even during the lowest point of solar activity, the Sun still blasts off a few of the most powerful X-class flares. Unprotected astronauts caught in the radiation would probably get pretty sick.
Apr 22, 2005 - New observations from the Solar and Heliospheric Observatory (SOHO) has helped solar astronomers trace the source of the Sun's solar wind. The solar wind is a constant stream of protons, alpha particles, heavy ions and electrons flowing from the Sun. The solar wind had been seen streaming from various regions on the Sun, but scientists have now been able to work out the structure of funnel-shaped magnetic fields that carry material from below the surface of the Sun, and eject it into space.
Oct 28, 2004 - The Sun is more active today than it has been in 8,000 years, according to new research from the Max Planck Institute. Researchers discovered that a certain isotope of carbon, C-14, depends on the amount of cosmic rays that reach the Earth's surface. When solar activity is high, the Sun's magnetic field provides a shield against these cosmic rays, and when it's low, the Sun lets more cosmic rays reach the Earth. By measuring C-14 levels in dead trees which were buried in the ground, the scientists were able to build up a historic record of solar activity. Scientists have found that solar activity levels only slightly influence the Earth's climate and global temperature.
Oct 18, 2004 - On October 11, solar astronomers saw something they haven't seen on the Sun in six years... nothing. Not a single sunspot. Within a couple of days, of course, a sunspot popped up, and they're on the Sun right now. This is a clear indication to astronomers that the Sun is on its way to the low point of its 11-year cycle of activity, called the "solar minimum". During the solar minimum, the Sun can be without spots for days or even weeks, and solar flares subside. Astronauts will breath a sigh of relief; it's a safer time to be out in space.
Sep 2, 2004 - A mystery that has puzzled astronomers for years is: why does the Sun's temperature rise as you get further away from it? While the surface of the Sun might only be 6000 degrees Celsius, the corona which surrounds it can be 2 million degrees. The "wave heating" theory proposes that the Sun's magnetic field carries waves of heat from the surface of the Sun and dumps them into the corona. Another theory proposes that lines in the Sun's magnetic field get twisted up and eventually snap, releasing a tremendous amount of energy into the corona.
Jul 29, 2004 - Scientists from Lockheed Martin and the University of Sheffield believe they've solved the mystery of supersonic jets that dart across the low atmosphere of the Sun. The team used computer modeling and high-resolution images taken with the Swedish 1-metre Solar Telescope to understand how these jets - called "spicules" - are formed. They noticed that the spicules formed in certain spots quite regularly, usually every five minutes or so. This matched sound waves on the Sun's surface that had the same five minute period. The sound waves are usually dampened before they reach the Sun's atmosphere, but wherever they aren't dampened, spicules are formed, propelling matter upward.
Jul 23, 2004 - Using data gathered by NASA's SORCE satellite, scientists noticed that the light from the Sun reaching the Earth decreased by 0.1% during the Venus transit earlier this year. This is similar to what happens when large sunspots obscure the face of the Sun. In October 2003, three large sunspot groups moving across the Sun dimmed it by 0.3%. These large sunspots are surrounded by bright areas called "faculae", which actually compensate for the dimmer spots, and provide a net increase in sunlight when measured over a period of a few weeks.
Jul 9, 2004 - The twin Voyager spacecraft, located at the edge of the solar system, have detected the effects of the most powerful solar storm ever detected, that blasted off the Sun in October/November, 2003. Thanks to a fleet of spacecraft, including Cassini, Mars Odyssey and the Voyagers, NASA scientists have been able to get a comprehensive view of how storms travel across the solar system. They hope that when the storm crashes into interstellar gas in a few more months, it will emanate radio waves detectable here on Earth.
Jul 2, 2004 - Scientists have used data from the SOHO spacecraft to build a 3D view of Coronal Mass Ejections (CMEs). CMEs are the most powerful explosions in the Solar System, and scientists believe they're caused when magnetic lines on the Sun get so tangled they "snap" back into position. This throws out millions of tones of electrified gas - sometimes directly towards the Earth, causing disruptions and beautiful auroras. The team viewed CMEs with SOHO, and found that the electrical field changed the light so that the 3D structure could be rebuilt on a computer.
Apr 30, 2004 - The light from the Sun seems regular and steady, but research from the University of Southern California paints a different portrait of a dynamic and chaotic star that experiences a range of events. Small forces acting deep inside the Sun can lead to significant changes on its surface, causing the flares and coronal mass ejections that can strike the Earth. Scientists are still trying to understand if there's a connection to the Sun's 11-year cycle of sunspots and temperature changes on the Earth.
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