The pretty #sunbeams that #light up a cheery spring day are made up of #particles that are between tens of thousands and hundreds of thousands of years old. #Photons that eventually become #sunlight start their journey in the core of the sun, forged in the furnace of powerful fusion reactions. They then have to #travel up to the surface and escape into #space, a process that takes eons. #science #ifls #iflscience #nature