The July presentation of the popular "The Universe Tonight" program will be presented at the Mauna Kea Visitor Information Station off Saddle Road. The Mauna Kea Program will be held on Saturday July 5, 2003 at the Onizuka Center for International Astronomy, located at the 9,300-foot level of Mauna Kea. The presentation will begin at 6pm, followed by stargazing with portable astronomical telescopes. The Visitor Information Station can be reached from Hilo, Waimea and Kona via Saddle Road. Seating is limited and will be provided on a first-come first-serve basis. The Universe Tonight is presented the first Saturday of each month at the Visitor Information Station. A special speaker from a different Mauna Kea observatory shares recent observations and discoveries with the general public. For more information on programs at the Mauna Kea Visitor Information Station visit the Web site www.ifa.hawaii.edu/info/vis or call (808) 961-2180. 2003, Saturday July 5, "The Universe Tonight' Presents: "Early Radio to Radio Astronomy" A Brief History of Radio & A Quick Introduction to Radio Astronomy Melanie Leong Caltech Submillimeter Observatory, 111 Nowelo Street, Hilo, Hawaii, 96720 Radio is a fairly new subject in terms of science and astronomy. Radio waves are part of the electromagnetic wave spectrum. Many of us receive transmitted radio waves for enjoyment, entertainment, and information. Today we have many mediums to chose from - amateur radio, shortwave radio, AM/FM radio, television, and satellite. A little more than a century ago radio did not exist. The general public had to communicate through letters that were delivered by Pony Express. But thanks to the theories of James Clerk Maxwell, and experiments by Heinrick Hertz, the beginning of radio was established. In 1884, Maxwell calculated that the speed at which electromagnetic waves travel is approximately the speed of light. He proposed that the phenomenon of light is therefore an electromagnetic phenomenon. Because charges can oscillate with any frequency, Maxwell concluded that visible light forms only a small part of the entire spectrum of possible electromagnetic radiation. In 1888, Hertz clarified and expanded Maxwell's electromagnetic theory of light. Hertz proved that electricity could be transformed into electromagnetic waves, which not only travel at the speed of light but also possess many of its properties. From Hertz's reports, Guglielmo Marconi, in 1896, built a wireless telegraph, a spark gap transmitter and receiver. This was used to bridge the Atlantic Ocean on December 12, 1901, from Poldhu, Cornwall, England to Signal Hill, Newfoundland. Marconi's spark gap station gained further acclaim when it was used on the Titanic, on April 15, 1909. All the people on board would have perished if it weren't for the ship's radio capability to send out a distress call when the ship struck an iceberg. A spark gap generator was the beginning hardware for radio. A spark is an electrical discharge that produces electromagnetic waves. These waves propagate through air, and can travel for very long distances. Early messages, however, were transmitted by short and long bursts of energy, or Morse code, not through speech. Soon after Marconi's spark gap generator, Reginald Fessenden developed a continuous wave transmitter in order to transmit speech. On December 23, 1906, Fessenden was able to transmit his own words to his colleague. The transmit and receive stations were only 1 mile apart, but this heralded the beginning of radio telephony. Further developments were made from 1906 to 1912. By 1924 spark was being phased out and not allowed on the newer amateur bands. Almost in parallel time with wireless development, the telephone was developed and put in service. In the early 1930's Bell Labs wanted to investigate using "short waves" (wavelengths of about 10-20 meters, 1 meter = 39.4 inches) for transatlantic radio telephone service. The American physicist, Karl Jansky was assigned the job of investigating the sources of static that might interfere with radio voice transmissions. In 1932, Jansky observed radio waves coming from the center of the Milky Way Galaxy. Jansky was not allowed to investigate this more. However, Grote Reber, a radio engineer, read about Jansky's observation and built the first radio telescope in his back yard in Wheaton, Illinois. By 1941, he measured and recorded the first radio sky map that is still used today as an introduction to radio astronomy. Objects in space emit electromagnetic waves. These wavelengths are as short as subatomic dimensions to longer than 600 miles! This large range requires the spectrum to be sectioned into bands. Radio is just a portion of the electromagnetic wave spectrum. The bands from the shortest to the longest wavelengths (with a relative size comparison) are: Gamma rays (atomic nucleus), X-rays (atom), Ultraviolet (virus), Optical (visible light), Infrared (bacterium), and Radio (sand grain to taller than a redwood tree). The Earth's atmosphere and ionosphere block the capability of viewing the full electromagnetic spectrum from the ground. Luckily there are a few windows in the optical, infrared, and radio bands. To observe these different bands, different instruments and observing techniques need to be used. This is the reason why there are various types of ground based as well as space based telescopes today. Ground based telescopes are built at high altitudes to get away from the noise and moisture present at lower elevations. The goal is to find a location where the climate is dry and the sky is clear. The summit of Mauna Kea meets these criteria. What is radio astronomy? It is the study of electromagnetic emissions from celestial objects that fall in the radio spectrum band. These emissions contain a wealth of information about what is going on in the Universe. Atoms and molecules in space emit their own unique electromagnetic waves that can be detected by radio telescopes. Magnetic field intensities and their direction can also be observed. There is a lot more to the celestial sky than what you can see. Radio telescopes can see "cold" objects, those that do not emit light, and can see radio sources behind interstellar dust clouds in parts of the Milky Way Galaxy that are hidden from optical viewing. Dust absorbs radiation at optical wavelengths, but radiation at radio wavelengths are not absorbed and travel through the dust. Radio telescopes can also detect distant galaxies at the edge of the Universe. From radio, wireless communication technology has boomed. From radio telescopes, we are able to learn even more about what is out there and the dynamic workings of our Universe. If you have the curiosity and perseverance, there is no limit to discovering new and exciting phenomena.