Astronomy Day - April 6, 2019 from 1-10pm

Moon PhotoAppreciating our Nearest Neighbor - FREE family-friendly activities, telescope observing, and planetarium shows focused on our Moon.

Join us at Sommers-Bausch Observatory and Fiske Planetarium for a full day of family-friendly activities including special talks, telescope observing sessions, light labs, scale solar system tours, stomp rockets, comet labs, and more!

Take a look at the full brochure with description of activities and our schedule. Come for an hour or stay all day. 

The CU Science Discovery, Boulder Astronomy & Space Society, and International Dark-Sky Association and will also join us to provide more activities and information.

Astronomy Day 2019 Partner logos

Public Open Houses

Free open houses are held on Friday evenings at 8:00 p.m. (9:00 p.m. in summer when Daylight Savings Time is in effect) when CU classes are in session (during the spring, summer A & B, and fall semesters.)

SBO Public Event.

SBO public event on the observing deck.

Open houses are only held when the skies are clear. If you're not sure if we'll be open, check out our local weather with instructions for calling ahead. 

There is no charge for the Observatory's Open House nights ... the stars are free to everyone!

Sessions typically last from 1-3 hours, depending upon the weather, the quality of the night, and the enthusiasm and size of the crowd (if unsure of observing status call 303.492.2020). Please stop by anytime after we open and stay as long as you wish.

We also have tripod-mounted binoculars and the world's largest starwheel (well, at least we think it is) for identifying bright stars and constellations. Depending upon the staffing on a particular night, we may be able to offer you a chance to visit the 24-inch telescope ... that mysterious tube hiding hiding inside the dome ... as well additional smaller telescopes set up on the open deck for looking at the Moon and other bright celestial objects.

Most of our evening programs are hosted by the APS Department's graduate students, with an occasional faculty professor, researcher, local amateur astronomer, and/or undergraduate volunteer on hand.

Date of Observing Time of Observing Lunar Phase (% Illumination)

January 18th, 2019

8:00 P.M.

88%  Illumination

Waxing Gibbous

January 25th, 2019 8:00 P.M.  77% Illumination

Waning Gibbous

February 1st, 2019 8:00 P.M.

11% Illumination

Waning    Crescent

February 8th, 2019 8:00 P.M.

10% Illumination

Waxing Crescent

February 15th,  8:00 P.M.

75% Illumination

Waxing  Gibbous

February 22nd, 2019 8:00 P.M.

90% Illumination

Waning Gibbous 

March 1st, 2019 8:00 P.M.

24% Illumination

Waxing Crescent

March 8th, 2019 8:00 P.M.

3% Illumination

Waxing Crescent

March 15th, 2019 8:00 P.M.

60% Illumination

Waxing Gibbous

March 22nd, 2019 8:00 P.M.

98% Illumination

Waxing Gibbous 

April 19th, 2019

(Large gap due to Spring Break).

8:00 P.M.

100% Illumination

Full Moon

April 26th, 2019 8:00 P.M.

56% Illumination

Third Quarter 

May 3rd, 2019 8:00 P.M.

3% Illumination

Waning Crescent