Suzanne Stewart
Staff Writer
The 59th annual Jansky Lecture last Wednesday evening at the Green Bank Observatory was an exami- nation of the history of “Discovering the Radio Universe.”
Speaker Dr. Ken Kellermann is a senior scientist emeritus at the National Radio Astronomy Observatory in Charlottesville, Virginia, and was awarded the Karl G. Jansky Lectureship in recognition of his significant contributions to research and major projects that have been critical to the development of radio astronomy.
Ironically, Kellermann did not set out to study astronomy when he was seeking an assistantship at CalTech. He was planning to study physics, until he met Professor John Bolton who was starting a new program in radio astronomy.
Kellermann began his research with Bolton almost immediately, and the rest, well, is history.
“That was sixty-five years ago, and the past sixty-five years have really been fantastic in radio astronomy,” he said. “Most of these discoveries were accidental or serendipitous. The scientists involved were mostly looking for something else. They were just looking and accidentally discovered something new.”
The birth of radio astronomy was in 1932, when Karl Jansky first detected radio waves from the central region of the Milky Way. He made this discovery using a directional antenna he built at Bell Telephone Laboratories. A full-size replica of the antenna – which was nicknamed “Jansky’s merry-go- round” because of its directional rotation – is located at the entrance of the GBO.
Jansky’s discovery inspired many radio astronomers, including Grote Reber, who built his own radio telescope in his backyard in Wheaton, Illinois. That telescope was moved and reconstructed on-site at the GBO, where it joins the Jansky replica as beacons of the history of radio astronomy.
Kellermann also has a history at Green Bank, where he was on the staff from 1965 to 1985.
During that time, Kellermann developed a new technique for extending the length of the interferometers. This technique helped pave the way for expanding the observational area across the world, by connecting telescopes in other countries to the telescopes at Green Bank.
Kellermann also worked with several undergraduate students who went on to make great strides in physics, astronomy and other scientific fields. He mentioned one undergraduate named Steven Chu whom he worked with in 1972.
Chu went on to win the Nobel Prize in physics and served as the U.S. Secretary of Energy from 2009 to 2013.
Kellermann quoted Chu, stating, “If you are the first person to look under a rock with a new set of tools, you don’t even have to be that smart to discover something new.”
With new radio telescopes, many discoveries were made, especially in the 1960s and 1970s, a great time in history for radio astronomy.
Kellermann shared a list of discoveries that include:
• 1933, cosmic radio emission
• 1938, non-thermal radiation
• 1942, solar radio emission
• 1943, solar radio bursts
• 1949, radio galaxies
• 1951, H1
• 1955, Jupiter radio bursts
• 1955, evolving universe
• 1962, radio recombination lines
• 1962, Venus rotation/temperature
• 1963, Quasars
• 1964, 4th test of GR
• 1964, Mercury rotation/temperature
• 1964, interplanetary scintillations/solar wind
• 1964, interstellar molecules
• 1965, CMB
• 1965, cosmic masers
• 1968, pulsars – neutron stars
• 1970, CO and giant molecular clouds
• 1971, superluminal motion
• 1974, gravitational lensing
• 1974, gravitational radiation
• 1975, solar deflection confirming GR
• 1991, exoplanets
• 2007, fast radio bursts
In pondering the decrease in the number of discoveries since the 1970s, Kellermann asked the questions, does this mean there is nothing left to discover or that the technology is now too old to make new discoveries?
He answered that there will always be more to discover in the vast universe and while the technology is still integral in making discoveries, the people trying to make the discoveries are what is really important.
As an example, he quoted Jocelyn Bell, who in 1967 during her postgraduate studies at Cambridge, detected a “bit of scruff” on her chart-recorder papers that tracked across the sky with the stars. The signal was visible in the data taken in August, but it took her three months to find it due to checking the read out by hand.
Although it took her longer than a machine to detect the signal, she wagered a machine would not have found it at all because the machines were not programmed to detect this certain kind of data.
Kellermann quoted her, stating, “If the aerial output had been digitized and fed directly to a computer, [pulsars] might well have not been discovered because the computer would not have been programmed to search for unexpected objects.”
In conclusion, Kellermann said there are still many unknowns out there for the radio astronomers of the future to discover.
After the lecture, Kellermann answered questions from the audience and a reception was held in the science center.