Astronomers don't know why Jupiter's iconic Great Red Spot has been gradually shrinking since the 1800s — or why the downsizing has accelerated during the past two years. Update: On May 15th, NASA released newly taken images of the Great Red Spot (at bottom below) to show its declining size…
The Greeks called them planētēs meaning “wanderers”. From Earth the other planets of our solar system look like roaming stars, but thanks to telescopes and spacecraft we know these pinpricks of light are actually worlds unto themselves, many with moons just as fascinating as they are. Among the most brilliant objects in the sky, some can be a great place to start your observing journey. Imagine Galileo peering up at Jupiter through his small telescope only to find four moons (Io, Europa, Ganymede, and Callisto) orbiting around it, the first proof we did not live in a geocentric universe.
Here you’ll find observing guides for the other planets orbiting the Sun, from bright Venus and red Mars to kingly Jupiter and elegant Saturn. We have software tools to help you find which planets or moons are visible tonight, when, and where. And we have guides highlighting neat features to look for on the planets when you do nab them in a telescope.