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Monthly Archives: August 2015

A careful restudy of the sunspot numbers reported by dozens of solar observatories around the globe and averaged in the Solar Influences Data Analysis Center at the Royal Observatory of Belgium has found some discrepancies, often based on individual observers’ idiosyncrasies. (See Section 10.2, p. 265 and Figure 10-18a, p. 268.)

The Center has provided the following revised sunspot count for this revision of The Cosmos, 4th ed.  It is updated, too, past the recent solar maximum, which peaked at different times in different solar hemispheres.


Credit: SIDC, Royal Observatory of Belgium

Links: Read more about their analysis and download comparison figures.


In this NY Times slideshow, Kenneth Chang curates a selection of images from NASA’s Cassini spacecraft’s farewell tour. Cassini entered orbit around Saturn 11 years ago; last fall, the space agency granted a final extension, through 2017, when the spacecraft will have exhausted the fuel for its thrusters. On August 17, it made its last flyby of Dione, the fourth largest of Saturn’s more than 60 moons, at 700 miles wide. Dione has its own mysteries that planetary scientists hope to unravel.

See the slideshow here (external link).