Ringed by mountains and capped by a temperature inversion that traps bad air, Los Angeles has had bouts of smog since the turn of the 20th century. An outbreak in 1903 rendered the skies so dark that many people mistook it for a solar eclipse. Angelenos might now be living in a state of perpetual midnight—assuming we could live here at all—were it not for the work of Caltech Professor of Bio-organic Chemistry Arie Jan Haagen-Smit. How he did it is told here largely in his own words, excerpted from Caltech's Engineering & Science magazine between 1950 and 1962. (See "Related Links" for the original articles.)

If you happen to see groups of people perched in the trees along Caltech's famed Olive Walk and Beckman Mall tomorrow, whacking at the branches with rakes and PVC pipes—rest assured there's nothin

Caltech clean-energy research is accelerating thanks to the renovation of the Earle M. Jorgensen Laboratory. Transformed into a cutting-edge facility for energy science, the lab unites two powerhouse programs: the Resnick Sustainability Institute and the Joint Center for Artificial Photosynthesis.