One of the more powerful techniques of radio astronomy is the use of interferometry to combine the signals of several radio antennas into a single virtual telescope. Through interferometry we can make radio images with resolutions greater than that of the Hubble telescope. But how does interferometry work?
Place of Departure
Chajnantor means “place of departure,” or more poetically “place of ascension” in the Kunza language of the Atacama region. It is a plateau about 5000 meters (16,000 feet) above sea level. It’s elevation and arid climate makes for extremely difficult working conditions, but it also makes it perfect for the Atacama Large Millimeter/submillimeter Array, or ALMA.
Pico Arcseconds
One of the advantages of radio astronomy is that you can connect observations from radio telescopes thousands of miles apart. Done in the right way, this creates a radio interferometer that effectively makes a virtual telescope as big as the separation (baseline) of the individual telescopes. The bigger your telescope (or virtual telescope), the finer the detail of your image. When we talk about the detail level of an astronomical image, we usually talk about the angle of separation between two distinctly resolvable points. So a resolution of a tenth of a degree would mean you could resolve two points of light (such as stars) separated by at least that angle.