This is the last chance to catch the pair in conjunction this year—with Venus set to be unusually bright in the night sky.

And be sure to get outside after sunset tonight (Feb. 1). For that evening a lovely crescent moon will appear to snuggle up close to Venus, particularly for skywatchers across the Western Hemisphere.

On Tuesday and Wednesday, Jupiter and Saturn will be joined on one side by a rising Mercury and on the other approached by a waning crescent Moon, creating a momentary line-up of four celestial ...