Plan Your Perfect Night

Enter your location and the planner rates every night from 1 to 10 for that spot. The galactic core has to be above the horizon at some point during astronomical darkness, or the night scores 0, which can happen at high latitudes even in midsummer. If the core is up, the moon's brightness sets the rating, with a 10 for a nearly new moon and lower scores as more of the moon is lit.

The core sits in Sagittarius. From the Northern Hemisphere it stays low toward the south, rising in the southeast and moving west through the night. From the Southern Hemisphere it climbs much higher and can pass nearly overhead in their winter.

The planner gives you rise and set times with compass directions for your location, so you can line the core up with a foreground before you drive out.

It depends on your latitude and the time of year. From Moab, at about 38°N, the core rises in the southeast a couple of hours after dark in early May, and it comes up earlier as the month goes on.

Farther north the window shrinks. Above roughly 48.5°N, summer nights never reach astronomical darkness. Iceland is the hard case: the summer sky stays bright, and at that latitude the galactic core doesn't clear the horizon.

A light pollution map tells you where the sky is dark, and the planner has one. The rating answers a narrower question: is this night worth it at this spot? Core position, moon, and darkness can be worked out years ahead, which is why planning months out works.