Robert McNees
Karl Jansky invented the field of radio astronomy #OTD in 1932.
During a solar eclipse he saw no change in the faint radio hiss he'd been monitoring, which ruled out the sun as a source. He soon attributed this "star noise" to large ionized gas clouds near the center of the Milky Way.
Robert McNees
Jansky was working for Bell Labs at the time, trying to identify radio static that interfered with trans-Atlantic telephone transmissions. He noted three different kinds of noise. The first two were related to nearby and distant storms.
Jansky built the antenna pictured above to measure this radio static. He called it his “merry-go-round” because it could rotate on a set of Model-T wheels. Using the antenna he initially found that the third source of radio hiss seemed to be coming from the sun.
Robert McNees
But the source seemed to have moved after a few months, and the fact that it didn't diminish during the eclipse conclusively ruled out the sun.
Instead, the source appeared to be in Sagittarius, and its peaks were timed with the sidereal period of 23 hours and 56 minutes.
This led Jansky to conclude that the source must be near the center of the Milky Way, which Jan Oort had pinpointed just 5 years earlier.
Robert McNees
Jansky published “Electrical disturbances apparently of extraterrestrial origin” the following year.
http://ui.adsabs.harvard.edu/abs/1933PA.....41..548J/abstract
Robert McNees
Jansky wanted to build a big radio dish to refine his observations, but his bosses at Bell felt like they already had the answers they needed. After all, they were just looking for the source of radio static that was impacting trans-Atlantic phone calls.
The investigation was closed, and Jansky moved on to other projects. He passed away in 1950 at the young age of 44.
Robert McNees
Many years later, at a ceremony dedicating a sculpture at the site of the original antenna, Jansky’s sister remarked that his persistence probably came from their father always telling them as children to "question everything."
Pretty big impact for a little star noise.
Robert McNees
It's pretty remarkable, the sheer volume of stuff we've learned about the Universe by pointing different sorts of antenna at the sky and asking “Huh, what's that noise?"
Robert McNees
@failedLyndonLaRouchite That's great.
OddOpinions5
Gerald Fink, Director of hte Whitehead Institute for Biomedical Research at MIT:
there are two kinds of biology, grind and find or stare and compare
j_bertolotti
@mcnees
🙋🏻♂️ Prof, why are we spending the whole lecture discussing about noise? Shouldn't we be talking about the signal?
👨🏻🏫 Well, I have a story for you...
Robert McNees
@xek Hello!
xek
@mcnees
(Also, hello from a fellow former denizen of Phillips Hall. Though my time was spent upstairs in the math department, except when I was working as a unix/linux admin for physics and astronomy. It was a great place to be as an undergrad.)
seachanged
On March 31, 2012, the VLA in New Mexico was renamed to the Karl G. Jansky Very Large Array.
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