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Tag Archives: sunspots

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.


From a NuSTAR mission press release:

A mission designed to set its eyes on black holes and other objects far from our solar system turned its gaze back closer to home, capturing images of the Sun. In December 2014, NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, took its first picture of the Sun, producing the most sensitive solar portrait ever taken in high-energy x-rays.


Credit: NASA/JPL-Caltech

While the sun is too bright for other telescopes such as NASA’s Chandra X-ray Observatory, NuSTAR can safely look at it without the risk of damaging its detectors. The Sun is not as bright in the higher-energy x-rays detected by NuSTAR, a factor that depends on the temperature of the Sun’s atmosphere.

This first solar image from NuSTAR gives insight into questions about the remarkably high temperatures that are found above sunspots. Future images will provide even better data as the Sun winds down in its solar cycle, with the potential to capture hypothesized nanoflares – smaller versions of the Sun’s giant flares that erupt with charged particles and high-energy radiation.

Links: NuSTAR press release, full-view image of the Sun’s disk.