A bright star and planet team up with the Moon early tomorrow to form a tight, beautiful triangle. Pollux will stand close to the lower left of the Moon, with much brighter Jupiter about the same distance to the lower right of the Moon. Pollux is the brightest star of Gemini, while Jupiter is a planet.

Jupiter is by far the giant of the solar system. It’s more than twice as massive as all the other planets combined. And it’s about 11 times the diameter of Earth. That makes it big enough to hold 1300 Earths.

But a recent study says that Jupiter might have been much bigger during its infancy – about two or two-and-a-half times its current diameter. That would have made it big enough to hold thousands of Earths.

Scientists came to that conclusion by studying the orbits of two of Jupiter’s small, close-in moons. The orbits are slightly tilted. Simulations showed that the moons were pushed into those orbits by the larger moon Io as it moved away from Jupiter. Those calculations revealed Jupiter’s original size and other details.

Jupiter probably formed in just a few million years – much quicker than most of the other planets. By then, the supply of planet-making materials had dried up. So Jupiter’s gravity began squeezing it and making it spin faster. Eventually, the planet reached a point where it couldn’t shrink any farther – leaving the smaller but still-giant world we see today.

Script by Damond Benningfield