How dark is the sky at Effigy Mounds National Monument?
When will the Milky Way be visible at Effigy Mounds National Monument in 2027?
Nights in each month when the Milky Way core stands more than 10° above the horizon for at least an hour of moonless astronomical darkness. At 43.1° north the core peaks at about 18° high, so a clear southern horizon matters. These are calculated positions of the sun, moon and Milky Way; whether a night is clear is only known closer to the date.
Has the sky over Effigy Mounds National Monument gotten brighter?
Each point is how much artificial light added to the natural brightness of the sky overhead that year: 0% is a natural sky, 100% means twice as bright. Same satellite every year; it barely sees the blue part of white LED light, so recent years probably read too dark.
Clear nights at Effigy Mounds National Monument by month
The average number of nights each month with less than 30% cloud, from NASA POWER satellite records.
Lights around Effigy Mounds National Monument seen from orbit
NASA satellite image of light at night, 2025. The rings mark distances from Effigy Mounds National Monument.
Where can you drive to the darkest sky at Effigy Mounds National Monument?
The darkest viewpoints, campgrounds, parking areas and trailheads you can drive to, up to about 60 km from the center of Effigy Mounds National Monument. Drive times from Prairie du Chien, the nearest town of 5,000 people or more (5 km SE).
None of these spots can be reached by car: there are no roads to them, or only by ferry or a long hike. Use them to see where the darkest land is.
A spot closed at night, or a number that looks wrong? Let us know.
Where are the observatories near Effigy Mounds National Monument?
Observatories within 150 km, with the modeled sky at each. Older ones often sit inside towns, newer ones were built where it is dark. Many are research or club sites, so check opening times before you go.
Almost black on purpose: there's next to no artificial light within this circle. This is what a dark sky looks like from orbit.
Which towns light up the Effigy Mounds National Monument horizon?
The compass shows where the glow on the horizon comes from, counting all light more than 5 km away. The table names the towns behind it, including Effigy Mounds National Monument's own outskirts.
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