150-foot Solar Telescope Tower

The 150-foot solar tower telescope was constructed to study the position, strength, and polarity of magnetic fields on the Sun. These measurements have been made since 1912, a record that allows long-term changes related to the 11-year sunspot cycle to be tracked.

The telescope is constructed vertically to take advantage of the steadier air above the Sun-baked ground. The central shaft is a conduit for the sunlight to travel from the mirrors and lens located at the top of the telescope to the instrumentation below.

The Solar Cycle Program is a long-term project at UCLA that uses this facility to provide high-quality maps of the Sun’s activity on a daily basis.

A camera mounted near the top of the tower shows various views around the observatory including the 100-inch telescope and the San Gabriel mountains (camera and service courtesy of the UCLA group at the 150-foot tower).