Entry No. 62 — the Boulder file — filed under: after-dark
Little Thompson Observatory Public Star Night
Tucked on the grounds of Berthoud High School, this volunteer-run observatory throws open its dome on the third Friday of every month for a free public star night. A guest speaker kicks things off at 7:30, then the real draw comes out: observing through a 24-inch Newtonian, an 18-inch Cassegrain and a 6-inch Astro-Physics refractor until about 10 p.m. No reservations needed, and the whole evening is free.
The story
Drive past the athletic fields behind Berthoud High School on a dark Friday night and you'll run right into something that feels like a state secret: a fully functional observatory dome sitting quietly in a high school yard. The Little Thompson Observatory wasn't erected by a massive university endowment or a federal grant, but built and maintained by local astronomy devotees who wanted to bring real, deep-sky optics out to the general public for free.
Inside the facility lies a serious collection of serious glass: a 24-inch Newtonian, an 18-inch Cassegrain, and a 6-inch Astro-Physics refractor. On the third Friday of each month, the volunteer crew throws open the doors, powers up the motors, and aims these heavy-duty barrels at whatever swirling galaxies, planetary rings, or dying stars happen to be swinging through the local night sky.
What it's like
Doors unlock at 7:00 p.m., giving you thirty minutes to claim a seat before the 7:30 p.m. guest talk kicks off. After the presentation, the main event begins as visitors head into the dome and out to the observation yard until about 10:00 p.m. Expect brief queues at the primary 24-inch eyepiece, but the volunteer astronomers keep things moving while explaining exactly what you're staring at light-years away. Key survival tip: dress much warmer than the ground temperature suggests. The dome stays unheated so rising thermal currents don't warp the telescope mirrors.
The move: Catch the 7:30 astronomy talk together, then step into the dome and peer through the big 24-inch telescope at whatever deep-sky object the volunteers have lined up.
📍 Before you go Third Friday of each month, weather permitting; doors 7 p.m., talk 7:30, observing 7-10. Free, no reservation. About 25 miles north of Boulder.
- 📍 Berthoud
- 💸 $
- ⚡ Low-key
- 🌗 Outdoors
Where: 850 Spartan Ave, Berthoud, CO 80513
Hours: Added 2026-06-23 — confirm current hours before you go.
⚠ Seasonal or scheduled — always check before you go.
Pair it with
- Quarters Bar + Arcade — Grab a quick bite and pour a few self-serve taps in downtown Longmont on your way north to Berthoud before turning your eyes to the skies.
- Tower of Compassion (Kanemoto Peace Tower) — Check out Longmont's surprising five-story Japanese pagoda in late afternoon before driving the remaining ten minutes north for the 7:00 p.m. observatory doors.
- Lyons Classic Pinball — Make it a full night of analog machinery by playing 70-plus vintage pinball tables in Lyons before driving over to look through massive manual-tracked telescope optics.
Good to know
When is the Little Thompson Observatory open to the public?
Public Star Nights take place on the third Friday of every month. Doors open at 7:00 p.m., the guest talk starts at 7:30 p.m., and telescope viewing runs until about 10:00 p.m.
Is there an admission fee or reservation system?
No. The event is completely free and requires no advance tickets or reservations—just show up at the high school grounds.
What happens if the weather is cloudy or bad?
Stargazing and dome viewing are strictly weather-permitting. If cloud cover or precipitation wipes out visibility, outdoor and dome observing gets scrubbed.
Where exactly is it on the high school campus?
It sits on the grounds of Berthoud High School at 850 Spartan Ave in Berthoud, about 25 miles north of Boulder.
Plan a visit & invite your people →
Further reading: starkids.org · nightsky.jpl.nasa.gov · berthoudhistoricalsociety.org
last checked: 2026-06-23