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Symmetry: How to Weigh a Galaxy Cluster

Step on a scale and you’ll get a quick measure of your weight. Weighing galaxy clusters, groups of hundreds or thousands of galaxies bound together by gravity, isn’t so easy. But scientists have many ways to do it.

SLAC, Stanford Scientists Play Key Roles in Confirming Cosmic Inflation

Two scientists at Stanford University and SLAC National Accelerator Laboratory made key contributions to the discovery of the first direct evidence for cosmic inflation – the rapid expansion of the infant universe in the first trillionth of a trillionth of a trillionth of a second after the Big Bang.

Mock Data, Real Science

In scientific circles, “mock” is not always a four-letter word. To test that they’re interpreting their massive amounts of data correctly, astrophysicists create even more data: “mock” data. And while that may be counterintuitive at first, it actually makes a surprising amount of sense.

Dark Energy Survey Begins

Word of the official beginning of the Dark Energy Survey (DES) starts a five-year clock on a meticulous mapping of one-eighth of the night sky by the Dark Energy Camera, mounted on the Victor M.

The Universe Through Fermi's Eyes

On June 11, 2008, what was then the Gamma-ray Large Area Space Telescope rode a Delta II rocket into low-Earth orbit. After two months of tests and checks and calibrations, on August 11, 2008, NASA declared GLAST open for business as astrophysics' premier eye on the gamma-ray sky. Five years, a name change, a near miss with a defunct Soviet spy satellite, and countless surprises later, the spacecraft now known as the Fermi Gamma-ray Space Telescope is still going strong, with another five-year mission stretching ahead of it.