mercoledì 26 luglio 2017

spaceweather eclipse

ANIMATED SOLAR ECLIPSE MAPS: The Great American Solar Eclipse is less than one month away. How much of the sun will be covered over your home town? A great way to find out: Animated eclipse maps created by science-artist Larry Koehn. On his web site, there are individual maps for all 50 US states as well as little-known eclipse zones in Canada and Europe. Check it out!
"WHITE SUNSPOT": Sunspot numbers have dropped to zero this week as dark cores associated with sunspot activity have vanished. Instead of dark spots, the sun has a light spot.  NASA's Solar Dynamics Observatory photographed this sprawling "white sunspot" on July 25th:

The correct name of this phenomenon is "faculae." It is a cousin of sunspots.
Regular dark sunspots are magnetic islands on the surface of the sun. Magnetic fields in these areas are typically thousands of times stronger than Earth's magnetic field. Sunspot magnetic fields are so strong, they block the flow of heat from the nuclear furnace below. They appear dark because they are relatively cool compared to their surroundings.
Faculae are also made of magnetic fields. However, the magnetism of faculae is concentrated in much smaller bundles than in sunspots. Instead of blocking heat from below, they essentially form corridors that allow us to see into sun's hot interior, creating an apparent bright spot on the surface of the sun.
These bright structures are more common than you might think. During the peak of a sunspot cycle, faculae actually win out over sunspots and make the sun appear slightly (about 0.1%) brighter at Solar Maximum than at Sunspot Minimum. Free: Solar Flare Alerts

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