For those who don’t already know, lo is essentially “the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of 3,642 kilometres (2,263 mi), the fourth-largest moon in the Solar System.” The red dot you see in the image above shows an active volcano spewing a blue cloud into space. Click here to see more of today’s most popular images, courtesy of Continue reading to watch National Geographic’s “Journey to the Edge of the Universe”.