Artificial light makes the modern world possible. But not all kinds of light are good for us. Electric light has fundamentally altered our lives, our bodies and the very nature of our sleep.
A decade ago, NASA's Cassini spacecraft, the largest and most complex robotic probe yet built, arrived in the Saturn system to begin a marathon exploration of the gas giant, its famous and awe-inspiring rings and what has turned out to be a collection of some of the most eye-opening moons in the solar system.
On July 19, NASA's Cassini probe captured a picture of the Earth and Moon, offering us a perspective of all of humanity on one tiny dot in space, and a reminder that Cassini is still out there exploring the distant reaches of the Solar System.