Solar flares are powerful explosions from the surface of the Sun which can eject tons of high-energy subatomic particles into space at nearly the speed of light. If the earth happens to be in the path of this dangerous, fast streaming solar material, beautiful aurorae may be seen, but significant damage can be done to fragile communications networks, electrical grids and earth-orbiting satellites. Thus it's in humanity's best interest to watch the Sun and keep an eye on the location of these deadly solar outbursts. Observations of the Sun with the Fermi Gamma-ray Space Telescope have shown how solar flares on the far side of the Sun can produce very high energy Gamma-ray emission on the side of the Sun facing earth. On three occasions (October 11, 2013, January 6 2014 and September 1, 2014) the sun-observing STEREO spacecraft, looking at the far side of the Sun, saw strong solar flares accompanied with ejections of matter. A few minutes later, Fermi's Large Area Telescope detected strong Gamma-ray emission from the near side of the Sun. These events were also seen at lower energies by the Fermi Gamma-ray Burst Monitor, the Reuvan Ramaty High Energy Solar Spectroscopic Imager (RHESSI) satellite, Konus-Wind, the Solar Dynamics Observatory (SDO), and the ground-based Radio Solar Telescope Network. The image above shows the localization of the September 1, 2014 flare seen by STEREO on the far side of the Sun, and the SDO and the LAT localizations of emission on the near side of the Sun. Scientists believe that fast moving subatomic particles generated by the flares on the far side of the Sun follow the Sun's bent magnetic field lines, which deflects them and causes them to rain down on the near side of the Sun, producing the Gamma-rays seen by the LAT.
NatGeo: Our Sun Produces Bizarre Radiation Bursts
GSFC: Fermi Sees Gamma Rays from 'Hidden' Solar Flares
Fermi-LAT Observations of High-Energy Behind-the-Limb Solar Flares - M. Ackermann et al
- Astrophysical Journal 835(2):219 (2017 Feb 01) DOI: 10.3847/1538-4357/835/2/219
arXiv.org > astro-ph > arXiv:1702.00577 > 02 Feb 2017
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