Re: Who found the center of our Galaxy? when and how?

We've been able to see the disk of the Galaxy throughout human history. It's the Milky Way, a band of dust and stars stretching around the whole sky. It's clear that this band is denser sort of in the direction of Saggitarius, but we can't pinpoint the center by eye.

In 1930, Robert J. Trumpler was the first astronomer to show that we are not at the center of the galaxy. It so happens that if you try to count how many stars can be seen in the Milky Way in various directions, it looks like we are at the center ... if you fail to account for dust and gas. Trumpler corrected for the dust properly, and showed that the galaxy is a disk-shape centered many kiloparsecs away.

In 1932, Karl Jansky directly observed the galactic center ... by accident. He was working on finding the sources of static that plagued Bell Telephone's ship-to-shore radio telephones. To do this, he built a movable, directional radio antenna, and pointed it in various directions to see where the noise was coming from. He was able to pinpoint a very strong radio source coming from the center of the Milky Way.

This discovery was quite fortuitous - he happened to have been using an excellent radio wavelength for this observation. However, he was largely ignored by astronomers, who were used to using only their eyes and photographic plates for observing. Bell Atlantic didn't find it too interesting, either, since it didn't help them to reduce static on their phones.

Grote Reber, however, followed up on Jansky's observation by building a real radio telescope. This was, really, the very first time that humans made observations of the universe without using their eyes - quite a revolutionary concept! His 1940 paper was entitled "Cosmic Static". Quoting from an article in Earth and Sky,

" Reber built his first radio antenna and receiver on land his family owned "in a far western suburb of Chicago ... free of the city's sources of spurious signals." His antenna was the first to use a paraboloid shape to focus weak radio signals. The choice of 31 feet for the width of the dish wasn't determined by the wavelengths of radio signals he wished to study. He later explained in a lecture that it was because, "in building the supporting superstructure the longest lumber available at the hardware stores in Wheaton was twenty feet, dictating a maximum diameter of thirty one feet for the dish." The dish could be tilted by use of a differential gear from a Ford Model T truck."

These were both largely amateur efforts. It was only in the 1950s, when the radar technology of WWII was put to work, that the astronomy community realized the importance of this new way of seeing.

A nice history of galactic observations can be found here, and a history of radio telescopes here.

Hope this helps!

-Ben Monreal