Solar X-rays:

Geomagnetic Field:

Karl Guthe Jansky was the father of Radio Astronomy. He was working for Bell Labs studying causes of interference in trans-oceanic shortwave radio and discovered a strange signal that wouldn’t go away. He finally realized that this signal was coming from Sagittarius at the center of our galaxy. His antenna was built on a circular track and slowly turned around, and people called it “Jansky’s merry-go-round.” He wanted to build a dish antenna measuring 30 meters across to study this new - found signal from space, but Bell Labs wouldn’t permit it. He died before he knew exactly what he had found. Later it was discovered that this signal was 21 centimeters in wavelength, and was generated by Hydrogen atoms in space. Today this signal is called the 21 Centimeter Hydrogen line. Later on, students at Harvard built a microwave antenna (horn) that received the signal and they recorded it for the first time. Below is a picture of their horn antenna which was mounted to the 4th floor of their window in a science building at Harvard.

Harold Ewen and  Edward Purcell built this horn receiver at Harvard University in search of the 21 cm signal generated by neutral Hydrogen atoms in the Milky Way Galaxy.

Photos courtesy of the NRAO/AUI/NSF

National Radio Astronomy Observatory

Associated Universities Inc

National Science Foundation

Click on the picture to read more about the work on this project.