Astronomy Picture of the Day—20180807

Discoverthe cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2018 August 7

Live:Cosmic Rays from Minnesota

ImageCredit: Fermilab, NuMI, NOvA Collaboration

Explanation:Cosmic rays from outer space go through your body every second. Typically, theydo you no harm. The featured image shows some of these fast moving particles asstreaks going through Fermilab's NOvA Far Detector located in Ash River,Minnesota, USA. Although the image updates every 15 seconds, it only showscosmic rays that occurred over a (changing) small fraction of that time, andmostly shows only one type of particle: muons. The NOvA Far Detector's mainpurpose is not to detect cosmic rays, though, but rather neutrinos from theNuMI beam shot through the Earth from Fermilab near Chicago, Illinois, USA, 810kilometers away. Only a few neutrino events are expected in NOvA per week,though. The NuMI / NOvA experiment is allowing humanity to better explore thenature of neutrinos, for example how frequently they change type during theirtrip. Cosmic rays themselves were discovered only about 100 years ago and cannot only alter computer memory, but may have helped to create DNA mutationsthat resulted in, eventually, humans.