General Articles

NASA’s Van Allen Probes discover a surprise circling Earth

Two giant swaths of radiation, known as the Van Allen belts, surrounding Earth were discovered in 1958. In 2012, observations from the Van Allen Probes showed that a third belt can sometimes appear. The radiation is shown here in yellow, with green representing the spaces between the belts. // NASA/Van Allen Probes/GSFC The twin spacecraft …

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NuSTAR helps solve riddle of black hole spin

This artist’s concept illustrates a supermassive black hole with millions to billions times the mass of our Sun. Supermassive black holes are enormously dense objects buried at the hearts of galaxies. // NASA/JPL-Caltech The findings resolve a long-standing debate about similar measurements in other black holes and will lead to a better understanding of how …

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‘Methuselah’ Star Looks Older Than the Universe

This Digitized Sky Survey image shows the oldest star with a well-determined age in our galaxy. Called the Methuselah star, HD 140283 is 190.1 light-years away. Astronomers refined the star’s age to about 14.5 billion years. Digitized Sky Survey (DSS), STScI/AURA, Palomar/Caltech, and UKSTU/AAO by Mike Wall, Space.com The oldest known star appears to be …

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Eerily Blank Sun

Something unexpected is happening on the Sun. 2013 was supposed to be the year of “solar maximum,” the peak of the 11-year sunspot cycle. Yet 2013 has arrived and solar activity is relatively low. Sunspot numbers are well below their values from 2011, and strong solar flares have been infrequent. The image above shows the …

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