302K views · 6.3K reactions | The blue glow is called Cherenkov...

748K views · 11K reactions | Where does NASA's James Webb Space Telescope get its energy? From the #Sun! It uses a 20-foot solar array to convert sunlight to electricity, providing all the power the spacecraft needs to #UnfoldTheUniverse. Be on the lookout for Webb’s first images on July 12! | NASA Space Alerts | Facebook

We are often taught that nothing can travel faster than the speed of light. This is true in a vacuum (like space). The universal speed limit, c, is unbreakable. But in a material like water, light actually slows down. In water, light travels at about 75% of its vacuum speed. This creates a loophole for high-energy particles. In nuclear reactors, subatomic particles (like electrons) are often ejected at speeds that are incredibly fast—faster than the speed of light *in water* (though still slower