Off The Beaten Path: McDonald Observatory

In the Fall of 2000 on our coast-to-coast tandem bicycle trip we passed the McDonald Observatory in the Davis Mountains of west Texas without stopping. In 2015 on our Roadtrek tour of the Southwest we stopped at this off the beaten path wonder and spent an enchanted four hours there learning about our Universe starting with our Sun. McDonald Observatory is on Texas route 118 about 39 miles south of I-10 and 39 miles north of Alpine, TX. Fortunately, 15 years made a lot of improvements — a new Visitor Center, Museum, and Star Party nighttime events where visitors can view celestial objects through large telescopes. Electric lights from cities are the anathema of observatories, and this location was selected because of its unusually dark sky and clear weather.

McDonald Visitor CenterThe Visitor Center Museum exhibits include real-time inspection of the Sun with its spots and solar flares, together with a scientific revelation of the physical aspects of our solar system's brightest star. Our position in our galaxy is located as well as our galaxy's place with regard to millions of other galaxies. We think of our Earth as large, but in comparison is like a grain of sand compared to the Rock of Gibraltar — the relative size of our Sun. Our Sun, on the other hand is a medium size star compared with some other giant stars that are thousands of times larger.

Smith Telescope - Inside

Harlan J Smith Telescope

The history of the McDonald Observatory starts with a one million dollar grant by a Texas land baron to the University of Texas to establish an observatory.  At the time the UT didn't even have an Astronomy program, but through a partnership with the University of Chicago, the McDonald Observatory was born.  The 82 inch Otto Struve telescope (named for the first director), completed in 1939 was at the time the 2nd largest in the world.  In the 1960s the partnership with University of Chicago ended and the University of Texas at Austin took control built the 107 inch Harlan J Smith telescope completed in 1968.  The Hobby-Eberly 30 ft telescope is a radically different design with a segmented mirror.  The past 25 years have seen several leaps forward in world class telescope design and an explosion of knowledge about our Universe.

View from Smith TelescopeA three-hour tour of the facilities took us to the next-to largest telescope, the Smith telescope. It was the second largest in the world when first built, but it has been modernized at intervals since that time, and is now 16th in size. It was the first computer controlled telescope and it has evolved through several generations of computers. NASA used it to measure the distance from Earth to the moon within six inches during the moon landing program. New instrumentation prototypes are tested on the Smith telescope, mostly spectrophotometers that gather and analyze light from distant stars and objects, breaking down the beams into their telltale signatures of elemental composition. We saw a new prototype sensor package the size of a small refrigerator on the end of the telescope that simultaneously gathers light from 256 objects. The successor to that instrument package will be installed on the observatory's largest telescope.

HET - OutsideOur guide explained that the astronomers today do not look through optical lenses and haven't for many years. The image of the bearded genius sitting on a high stool with his eye glued to the eyepiece is a cliché of the past. We saw a dormitory where visiting scientists live on an inverted daily cycle — they sleep in daytime and spend the night investigating the sky.

HET - DiagramWe next went to the largest telescope in the observatory, which is an innovative modern design with a segmented primary mirror. This relatively low cost telescope is several hundred times larger than the Smith telescope. When we were there it was being upgraded to resolve ever more minute light emissions from the cosmic big bang 13 billion years ago (more or less.) We were given a Niagara Falls of statistical data about what it could do and what it will do when the new instrument packages are installed several years from now. There's no end in sight!

One piece of data stuck with us. Most stars have planets. Astronomers have cataloged these planets and are investigating those that potentially have atmospheric conditions similar to our Earth. So far there appear to be about a billion (maybe only a million) such planets. Visiting the nearest of these may take a million years. OK, Class B owners, start your engines!





  • Carol

    Really cool! P.S. You two did a tandem bike ride coast to coast??? I’d love to hear more about that too.