Entry No. 60 — the Boulder file — filed under: after-dark
Sommers-Bausch Observatory Friday Open House
Up on the observing deck behind Fiske, CU astronomy students swing the observatory's 20-inch telescopes toward the Moon, planets, nebulae and distant galaxies for anyone who shows up. Open houses run most Fridays when classes are in session, starting at 9 p.m. in summer once daylight saving stretches the dusk, and they only happen when the sky is actually clear. It is completely free, and a session can stretch one to three hours depending on the seeing.
The story
Most campus wanderers walk right past Fiske Planetarium's geodesic dome without giving a second thought to what sits directly behind it. Built in 1953 using a bequest from Mayme Sommers in memory of her husband Elmer and supported by optics pioneer Carl L. Bausch, the Sommers-Bausch Observatory was constructed in an adapted rural Italian style to match CU Boulder's brick architecture. Operated by the Department of Astrophysical and Planetary Sciences, it spends the school week as a working laboratory where students map solar activity and learn observational physics.
When Friday night rolls around and CU classes are in session, the department quietly opens the rooftop observing deck to anyone who climbs the stairs. Graduate student astronomers and professors point the observatory's 20-inch Planewave CDK telescopes—named Artemis and Apollo—at whatever happens to be passing through the clear night sky, from Saturn's rings and Jupiter's moons to distant nebulae and dark lunar craters. You won't find ticket booths, corporate sponsors, or souvenir stands up here—just student astronomers aiming heavy glass at deep space and taking questions from whoever shows up.
What it's like
You head up to the open-air observing deck behind Fiske, where the mountain air turns crisp and twin 20-inch telescopes sit pointed toward the dark. The setup is casual: student hosts align optics, guide visitors up short step ladders to look directly through eyepieces, and broadcast live camera feeds on outdoor screens so everyone can see. You might spend a few minutes in a short line waiting to inspect a star cluster or planet while an astronomy grad student breaks down the physics. The main catch is total weather dependence—if overcast skies cover Boulder, the deck stays closed. Call 303-492-2020 after 7:45 p.m. or check their Facebook or Instagram accounts around 7 p.m. to confirm it is a go before making the trek.
The move: Climb to the rooftop deck after dark and take turns at the big 20-inch scope, letting a student astronomer talk you through whatever planet or galaxy is up that night.
📍 Before you go Friday nights only when CU is in session and skies are clear; call 303-492-2020 after 7:45 p.m. or check their socials at 7 p.m. for go/no-go. Free, no reservation.
- 📍 CU Boulder campus, Boulder
- 💸 $
- ⚡ Low-key
- 🌗 Outdoors
Where: 2400 Colorado Ave, Boulder, CO 80309
Hours: Added 2026-06-23 — confirm current hours before you go.
⚠ Seasonal or scheduled — always check before you go.
Pair it with
- Fiske Planetarium Late-Night Laser Shows — Catch a late-night music-and-laser show under Fiske's 65-foot dome right next door before or after heading up to the observing deck.
- The Sink — Head less than a mile west to University Hill for a burger inside Boulder's oldest tavern, open since 1923 with walls and ceilings covered in art and signatures.
- Columbia Cemetery — Trade looking up at distant stars for walking among 1870s gravesites at Boulder's oldest burial ground a mile west.
- Crystal Dragon — Shift from observing planets through scientific optics to browsing raw minerals and gemstones at one of Boulder's longest-running metaphysical shops.
Good to know
Do I need tickets or a reservation?
No tickets or reservations are required. Open house sessions are completely free and operate on a walk-up basis on the observing deck.
How do I confirm if the open house is on or canceled due to weather?
Open houses only run when skies are clear. Call 303-492-2020 after 7:45 p.m. on Friday, or check the observatory's Facebook or Instagram pages at 7 p.m. for the go/no-go status.
What time do the open house sessions start?
Sessions typically start at 8 p.m. during the school year, shifting to 9 p.m. in the summer once daylight saving pushes back dusk. They run for one to three hours depending on weather and seeing conditions.
Is the observing deck accessible if I cannot climb a step ladder?
Yes. While peering directly through some telescope eyepieces requires stepping up a small ladder, the observatory displays live feeds from camera-equipped scopes on large outdoor screens on the deck.
Plan a visit & invite your people →
Further reading: colorado.edu · Wikipedia · Reddit
last checked: 2026-06-23