In what’s called a “great conjunction,” the two largest planets in our solar system will appear closer to each other in the night sky than at any point in almost 400 years.

The James Webb Space Telescope will soon investigate stunning light shows from Uranus and Saturn as two projects look at the auroras of these planets to discover the processes that make them tick.

It will be the closest alignment of Saturn and Jupiter, the largest planets in our solar system, since 1623. But that conjunction, just 14 years after Italian astronomer Galileo Galilei built his ...