Cosmic Ripples

When the cobe satellite in 1992 mapped the faint microwave glow left over from the Big Bang, it couldn’t make out structures as small as individual galaxies, or even clusters of galaxies. Astronomers would dearly have liked to get a glimpse of such structures to find out more about how galaxies were born. Now a team of researchers at Cambridge University in England has found a way to zoom in on the primordial structure of the universe, creating images 60 times sharper than cobe’s--from the ground. The Cosmic Anisotropy Telescope uses three antennas spaced about six feet apart to take advantage of a technique called interferometry. A newly developed computer program analyzes signals from the three antennas and filters out random signals from water vapor in the atmosphere, which are a million times stronger than the cosmic background, leaving only constant signals from cosmic microwaves. cat team leader Paul Scott says, Without interferometry, any sort of observation would be impossible at a sea-level site like Cambridge. This image shows a small section of the sky near the Big Dipper. The bright orange and white areas are regions of high density-- perhaps the seeds of what later became galaxies while the microwaves were traveling to Earth from the edge of the universe. The Cambridge team plans to build a larger version of cat in the Canary Islands in order to map these cosmic wriggles all over the sky.