Tonight and tomorrow night (January 9 and 10,) the waxing crescent Moon will rise and set with our solar system’s largest planet, Jupiter. You’ll find the pair high above your SW horizon at sunset and setting into the west by about 10:30 pm. If you’re up to a fun challenge, grab a pair of binoculars to see if you can spot Jupiter’s four brightest moons to either side of Jupiter, and the planet Uranus to the very near lower-right of Jupiter.
While these two may appear close together, they are actually 365-million to more than 500-million miles apart. As you look at them together, consider their many differences. Jupiter is a gas-giant planet measuring nearly 90,000-miles at its diameter; Luna is a rocky “satellite” roughly 1/4 the radius of Earth. Jupiter completes one solar orbit in twelve years; the Moon completes an Earth orbit in just over twenty-seven days. Surprisingly, though Jupiter dwarfs the Moon, it completes one axial rotation in just over nine hours, while one full day on the Moon, from one sunrise to the next, is equal to 29.5 days.
