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The Sun

The Sun is now in the quietest phase of its 11-year activity cycle, the solar minimum – in fact, it has been unusually quiet this year – with over 200 days so far with no observed sunspots. The solar wind has also dropped to its lowest levels in 50 years. Scientists are unsure of the significance of this unusual calm, but are continually monitoring our closest star with an array of telescopes and satellites. Seen below are some recent images of the Sun in more active times. (text by The Boston Globe)

A sweeping prominence, a huge cloud of relatively cool dense plasma is seen suspended in the Sun’s hot, thin corona. At times, promineces can erupt, escaping the Sun’s atmosphere. Emission in this spectral line shows the upper chromosphere at a temperature of about 60,000 degrees K (over 100,000 degrees F). Every feature in the image traces magnetic field structure. The hottest areas appear almost white, while the darker red areas indicate cooler temperatures. (Courtesy of SOHO/EIT consortium)

A view of a sunspot and granules on the Sun’s surface, seen in the H-alpha wavelength on August 4, 2003. (Swedish 1-m Solar Telescope (SST) operated by the Royal Swedish Academy of Sciences, Göran Scharmer and Kai Langhans, ISP)

NASA’s STEREO (Ahead) spacecraft observed this visually stunning prominence eruption on Sept. 29, 2008 in the 304 wavelength of extreme UV light. It rose up and cascaded to the right over several hours, appearing something like a flag unfurling, as it broke apart and headed into space. The material observed is actually ionized Helium at about 60,000 degrees. Prominences are relatively cool clouds of gas suspended above the Sun and controlled by magnetic forces. (NASA/STEREO)

A transit of the Moon across the face of the Sun on February 25, 2007 – but not seen from Earth. This sight was visible only from the STEREO-B spacecraft in its orbit about the sun, trailing behind the Earth. NASA’s STEREO mission consists of two spacecraft launched in October, 2006 to study solar storms. STEREO-B is currently about 1 million miles from the Earth, 4.4 times farther away from the Moon than we are on Earth. As the result, the Moon appears 4.4 times smaller than what we are used to. (NASA/STEREO)

For MORE photos, illustrations, and information.

post by Wanderlust

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