See Io, our most volcanic moon, erupt like never before

the most volcanically active world is Jupiter’s innermost large moon: Io. <img alt="" src="https://miro.medium.com/v2/resize:fit:675/0*soOgAtxUbkF_LE5x" style="height:444px; width:675px" /> When one of Jupiter’s moons passes behind our Solar System’s largest planet, it falls into the planet’s shadow, becoming dark. When sunlight begins striking the moon again, we don’t see it instantly, but many minutes later: the time it takes for light to travel from that particular moon to our eyes. Here, Io re-emerges from behind Jupiter, the same phenomenon that Ole Rømer used to first measure the speed of light, while Europa and Ganymede hover on the right. (<a href="https://imgur.com/5DvC9IU" rel="noopener ugc nofollow" target="_blank">Credit</a>: Robert J. Modic) <a href="https://medium.com/starts-with-a-bang/see-io-our-most-volcanic-moon-erupt-like-never-before-22eaa83f9793">Website</a>