Exploratorium home Exploratorium home Explo.tv
Browse programs by:
Search 
00:04:05
On the cliffs above San Francisco's Ocean Beach perches a landmark observatory—a giant camera obscura. Step inside with Robert Tacchetto and see how this centuries-old technology creates enchanting images of the outside world.

00:03:53
Join Exploratorium educator Ken Finn as he unlocks the mystery behind the black sand (a.k.a. magnetite) at Ocean Beach. This piece explores the origin of magnetite in the Sierra Nevada mountains, its journey down the Sacramento and San Joaquin rivers to the Bay, and the interesting physical properties of this mineral, plus some fun things you can do with it.