Physics Colloquium: The John Bahcall Lecture in Astrophysics

Title: Estimating distances in astronomy

Abstract:
 
How do we estimate the distance to the Moon, planets, stars, and galaxies? Observations of celestial objects are inherently a 2D mapping on the sphere but astrophysical studies usually require the knowledge of 3D positions.

I will review the collection of techniques that have been used so far to estimate distances: from laser and radar ranging in the Solar system, parallaxes within our own Galaxy, to the use of redshifts on cosmological scales. I will then describe the new challenges we face when it comes to estimating distances with the latest sky surveys, mapping out millions of galaxies across the Universe. Finally, I will present a new approach to distance estimation, based on the clustering of objects on the sky.

I will apply it to various astronomical observations at UV, optical, IR, and radio wavelengths and will show a number of surprises.
 

Event Organizer: Prof. Ben Svetitsky