Sundials

Dr. Reiff was instrumental in the design of the Cockrell Sundial at the Houston Museum of Natural Science (HMNS), calculating the hour/month lines and inventing the special silver ball on the top of the dark gnomon. That ball creates Houston's special "stonehenge", casting an image of the sun near solar noon for a week or two around the equinoxes and solstices, allowing easy viewing of sunspots. First opened in September 1989, the sundial has kept perfect "solar time" for more than 35 years.

Sundial Events

We will be hosting live events for every solstice and equinox at the Cockrell Sundial at the Houston Museum of Natural Science. The next event will be the FALL EQUINOX, Monday September 22, 2025, 12-2 pm. Don't miss our first-ever equinox at (almost) exactly solar noon! The Sun will cast an image through the sundial (weather permitting) from about 1 pm to 1:30 pm with the very best at 1:14.

Cockrell Sundial Information

Past Events

Cockrell Sundial at HMNS

The following documents are courtesy HMNS and the Rice Space Institute and may be freely copied for non-commercial educational use.

• Cockrell Sundial Information (PDF)
• Scale model of the Cockrell Sundial at HMNS (PDF)
• How to use the HMNS sundial (from HMNS.org)

Cockrell Sundial Timelapse

720x720 fisheye MP4

1280x720 flat MP4