Satellites that detect gamma rays from solar flares primarily include space-based observatories equipped with specialized instruments designed to observe high-energy photons. The most notable among these is the **Fermi Gamma-ray Space Telescope**, particularly its Large Area Telescope (LAT), which has been instrumental in detecting and cataloging gamma rays emitted by solar flares.
Solar flares are intense bursts of radiation caused by magnetic energy release on the Sun, producing a wide spectrum of electromagnetic radiation, including gamma rays. These gamma rays can range from tens of millions to billions of electron volts (MeV to GeV energies). Detecting such high-energy emissions requires sensitive instruments placed above Earth’s atmosphere because the atmosphere absorbs gamma rays, preventing ground-based detection.
The **Fermi-LAT** has significantly advanced our understanding of solar flare gamma-ray emissions since its launch in 2008. It detects photons in an energy range from about 30 MeV up to tens of GeV. Over nearly a decade, Fermi-LAT compiled a catalog identifying dozens of solar flares emitting in this high-energy regime during Solar Cycle 24 (2010–2018). This includes observations not only from visible active regions on the Sun but also from areas beyond the visible edge, revealing complex particle acceleration processes involving protons and ions alongside electrons.
Before Fermi-LAT, earlier satellites like **EGRET** aboard NASA’s Compton Gamma Ray Observatory first observed solar flare gamma rays back in 1991. EGRET was capable of detecting photons above about 20 MeV and provided initial evidence that solar flares could produce significant nuclear interactions leading to high-energy emission.
Other satellites originally designed for different purposes have also contributed indirectly or historically:
– Some early defense satellites intended for nuclear test monitoring detected unexpected cosmic and solar gamma-ray events.
– Instruments aboard missions like RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager) focused on X-rays and lower-energy gamma-rays helped characterize flare emissions but were limited compared to LAT’s higher energy reach.
Ground-based observatories cannot directly detect these primary solar flare gamma rays due to atmospheric absorption; however, they complement satellite data by observing secondary effects or very-high-energy cosmic phenomena.
In summary:
– The **Fermi Gamma-ray Space Telescope’s Large Area Telescope (LAT)** is currently the premier satellite instrument detecting high-energy (>30 MeV) gamma rays from solar flares.
– Earlier detections came from instruments like **EGRET** on Compton Gamma Ray Observatory.
– These satellites reveal that besides electrons traditionally associated with flare emissions, accelerated protons and ions play a crucial role in producing observed high-energy gammas through processes such as pion decay.
This capability allows scientists not only to monitor energetic events on our Sun but also better understand particle acceleration mechanisms during these explosive phenomena.