Griffith Park Above the Fire
Griffith Observatory was first opened in 1935 and reopened after a long renovation in November 2006. It has been backdrop for movies from REBEL WITHOUT A CAUSE to THE ROCKETEER. The site has a wonderful view of Los Angeles lights, which makes it terrible for observing but a great asset to the community.
Visitors: You can no longer drive here. You must purchase your tickets online and take one of the shuttle buses up the hill. Thus place is popular as a Hollywood premiere, and is expected to be very busy this Summer. It is nice to see so many people interested in astronomy!
Nearby atop Mount Wilson stands the 100-inch Hooker telescope, once the largest in the world. When this telescope saw first light in 1917, astronomers disagreed whether our Milky Way represented the entire Universe. Andromeda was called a nebula, and no one agreed whether it was part of our galaxy or outside. Using the Hooker telescope, Edwin Hubble determined that "spiral nebulae" were in fact distant galaxies.
Albert Einstein theorised that the Universe was spherical in four dimensions rather than three. Every bit would resemble every other bit. He realised that gravity would cause the Universe to collapse, UNLESS it were already expanding. Einstein could have predicted an expanding Universe, but instead introduced a repulsive "cosmological constant" opposing gravity.
Hubble and his colleague Milton Humason relied upon a class of stars called Cepheid Variables. These stars vary periodically in brightness, with a period related to their luminosity. Observing a Cepheid’s period would tell them how much light the star gave off. By measuring how much of that light reached Earth, they cold determine distance to the star and galaxy. Cepheid Variables were standard candles measuring the distance to their galaxies.
Redshift is approximately v/c, an object’s velocity divided by the speed of light. When the redshifts of many galaxies were plotted against their distances, those redshifts increased linearly with distance. This did not indicate that our galaxy was unpopular. If the Universe was spherical like a balloon, the galaxies were like spots on its surface. As a balloon expanded, the spots would increase their distance uniformly. A galaxy twice as distant would recede twice as fast. The distance-redshift relation was convincing evidence that our Universe was expanding.
In a well-publicised 1931 visit to Mount Wilson, Einstein conferred with Hubble and peered through Hubble’s telescope. The world’s most famous scientist happily accepted the expanding Universe. Hubble’s data convinced Einstein to drop the cosmological constant, later calling the CC his “greatest blunder.” If Einstein called something a blunder he was probably right.
UPDATE: As this was posted, a huge fire has erupted in Griffith Park, visible for miles. Fortunately it is a big park and the fire is on the opposite side. The observatory has been closed as a precaution. Southern California has been very hot and dry.
UPDATE: As of midnight PST, the fire has not been contained and is inching closer to the observatory. Residents of Los Feliz have been ordered out. The view is eerily similiar to the Oakland Hills fire of 1991. This could get bad.
UPDATE: This morning the observatory appears out of danger. The fire had been moving North toward the zoo, and was expected to die down by sunset. Instead the wind shifted South toward the observatory and the Los Feliz neighbourhood. The fire is still burning and large parts of Griffith Park are black.