Simple Interferometer

Build your own Simple Interferometer - a virtual radio telescope - using Nasa’s educational radio telescope kit.

Size matters in astronomy. It matters most in radio astronomy where the extremely long wavelengths require extremely large radio antennas. Larger radio telescopes can see farther back in time with higher resolution. The pressure to build ever-larger telescope only increases as astronomers try to understand the nature of the black holes lurking in the center of galaxies, peer into the distant origins of the Universe, and peek through the dust clouds obscuring the Milky Way.

The engineering costs of single-dish radio telescopes make larger projects prohibitive. Fortunately the technique of interferometry lets professional astronomers build telescopes on a global scale. Interferometry links multiple telescopes together to create a single virtual telescope. The famous Very Large Array in the deserts of New Mexico links twenty-seven 25-meter diameter radio dishes into a virtual telescope up to 36 kilometers across. The Square Kilometer Array being built in Australia and South Africa will link thousands of radio telescope to create a 3,000 kilometer baseline.

Amateur radio astronomers face challenges similar to the professionals but on a smaller scale. While some advanced amateurs use radio dishes several meters across, building a personal radio telescope is as simple as stringing wire between two posts. Nasa’s Radio Jove project sells a kit that lets schools build this simple radio telescope to detect radio signals from Jupiter or the Sun.

Staff at the Australia Telescope National Facility extended that kit into the world of radio interferometry. They documented the Simple Interferometer on the fringes.org website. Setting up two Radio Jove telescopes and using slightly more advanced electrical circuits, you can turn the separate telescopes into a single radio telescope. The Simple Interferometer can detect radio sources far beyond the Solar System. In one test the project team detected radio emissions from Centaurus A - a galaxy eleven million light years away. You can use the Simple Interferometer to observe things a little closer to home. When one of the most powerful recorded solar flares erupted from the Sun’s surface in 2003, it quickly overwhelmed Noaa’s space weather sensors. As reported in Australia and by Nasa, the Simple Interferometer team used their own data to calculate the strength of the flare.

Although the Fringes website hasn’t been updated in several years, it provides a good background on radio astronomy, interferometry, and the steps you need to take to build your own radio telescope