Parallax is the most reliable method for directly measuring distances to stars within our galaxy. It uses the geometry of the Earth's orbit around the Sun to see tiny, almost imperceptible shifts of background stars behind the object being measured.
Previously this technique was only effective for distances up to 750 light years. Anything further away and we couldn't see the background stars shift; the change was too small.
This new capability allows astronomers using the Hubble Space Telescope to measure parallax distances up to 7,500 light years away - an astonishing increase in precision of a factor of 10!
Please join us as and discuss this new technique with Dr. Adam Riess, winner of the 2011 Nobel Prize in Physics and Dr. Stefano Casertano, the developers of this new ability for #Hubble .