Trillions of neutrinos pass through our bodies every second. The sun produces them through fusion; so do nuclear power plants. Some come from supernova explosions in space. Neutrinos pair with antineutrinos, which scientists think mirror their behavior. 

So JUNO is designed to capture antineutrinos — specifically, those emitted from two nuclear power plants about 33 miles away from the observatory.

JUNO’s sphere, which is 13 stories tall, will be filled with a special liquid called…