Karl Guthe Jansky

Karl Jansky was a radio engineer.

He built a large tool to listen for signals. It sat on wheels and could turn around.

One day, he heard a soft hiss. This hiss was not from a storm. It came from the Milky Way. The signal came from the center of our galaxy. This was a big discovery!

Now, scientists use his name to study space.

Karl Jansky was a radio engineer.

He worked at Bell Telephone Laboratories. His job was to find static. Static is noise that can mess up radio calls.

He built a large antenna to listen for waves. It was 100 feet wide. It sat on wheels so it could turn. People called it "Jansky's merry-go-round."

After months of work, he heard a strange hiss. It was not from a thunderstorm. It did not come from the Sun. He found the hiss came from the Milky Way. This is our home galaxy. The signal was strongest near the constellation Sagittarius.

This was the start of radio astronomy. This is the study of space using radio waves.

Many people did not know how big this was at first. Later, scientists used his ideas to learn more. Today, his name is very important. A unit for measuring radio signals is called a jansky. There is even a crater on the Moon named after him.

Karl Jansky was a very important radio engineer and physicist.

He was born in 1905 in the Oklahoma Territory. His father was a dean at the University of Oklahoma. This family had a strong interest in science and engineering. Karl went to the University of Wisconsin for college. He earned a degree in physics in 1927. Later, he worked at the Bell Telephone Laboratories in New Jersey.

His main job was to study radio static. He wanted to find noise that might mess up phone calls. This work led him to a huge discovery about space.

To find the source of the noise, Jansky built a large antenna.

It was 100 feet wide and 20 feet tall. The antenna sat on a turntable with Ford Model-T wheels. Because it could spin, people called it "Jansky's merry-go-round." He used a pen and paper to record the signals. He first found static from nearby and distant thunderstorms. Then, he heard a faint, strange hiss of unknown origin. He spent over a year trying to find where it came from.

Jansky noticed the hiss followed a very specific cycle. It repeated every 23 hours and 56 minutes. This is called a sidereal day. A sidereal day is the time it takes stars to pass in front of a spot on Earth. This meant the signal was coming from space, not the ground. He thought it might be the Sun at first. However, the signal was strongest in the direction of the Milky Way. Specifically, it came from the constellation Sagittarius.

He announced this discovery in April 1933.

Jansky's discovery was quite surprising to many people back then. In 1933, he published his findings in a science journal. He even spoke about "radio sounds from among the stars" on NBC. At first, many astronomers did not realize how important this was. The Great Depression made it hard to fund new research. Later, other scientists like Grote Reber helped the field grow. Reber built his own radio telescope in his backyard in 1937. These steps helped turn radio astronomy into a real science.

Today, we remember Karl Jansky in many wonderful ways. Scientists use a special unit called a "jansky" to measure radio signals. There is even a crater on the Moon named after him.

A large telescope in New Mexico is named the Karl G. Jansky Very Large Array. You can also see a full replica of his antenna in West Virginia.

His work changed how we look at the night sky. We no longer just use light to see the universe. We use radio waves to listen to the stars too.

Karl Guthe Jansky was an American physicist and radio engineer. He is known as a founding figure of radio astronomy. This is the study of celestial objects using radio waves instead of visible light. In April 1933, Jansky announced he had found radio waves coming from the Milky Way. His discovery changed how humans observe the universe.

Jansky grew up in a family with deep scientific roots. He was born in 1905 in the Oklahoma Territory. His father, Cyril M. Jansky, was the dean of engineering at the University of Oklahoma. Karl attended the University of Wisconsin for his studies. He earned a Bachelor of Science in physics in 1927. He later completed graduate coursework for a master's degree in physics. In 1928, he joined the Bell Telephone Laboratories in New Jersey. He moved to Holmdel because of a kidney condition.

At Bell Labs, Jansky was assigned to investigate sources of static. This static could interfere with trans-Atlantic radio telephone services. He built a large, directional antenna to study these signals. The antenna was about 100 feet in diameter and 20 feet tall. It operated at a frequency of 20.5 MHz. The device sat on a turntable with Ford Model-T wheels. This allowed the antenna to rotate in the azimuthal direction. People called it "Jansky's merry-go-round."

Jansky used an analog pen-and-paper system to record signal intensity. He categorized the static into three distinct types. The first type came from nearby thunderstorms. The second type came from distant thunderstorms. The third type was a faint, mysterious "hiss" of unknown origin. Jansky spent over a year investigating this third signal. He noticed the intensity rose and fell once every day. At first, he thought the radiation came from the Sun.

Jansky eventually realized the signal was not from the Sun. He found the signal repeated on a cycle of 23 hours and 56 minutes. His friend, Albert Melvin Skellett, identified this as a sidereal day. A sidereal day is the time it takes fixed stars to pass overhead. This proved the signal came from astronomical objects. By comparing his data to maps, Jansky located the source. The radiation was strongest in the direction of the Milky Way. Specifically, it came from the constellation Sagittarius.

Jansky announced his findings in April 1933. He published a paper titled "Electrical disturbances apparently of extraterrestrial origin" later that year. He even discussed "Radio sounds from among the stars" on NBC. In 1935, he suggested the signals came from interstellar gas. He believed this was caused by the thermal agitation of charged particles. Despite this, radio astronomy remained a quiet field for a while. The Great Depression made it difficult for observatories to fund new research.

Other scientists eventually built upon his work. Grote Reber built a radio telescope in his backyard in 1937. He performed the first systematic survey of radio waves. John D. Kraus later started a radio observatory at Ohio State University. Jansky's legacy is preserved in many ways today. Scientists use the "jansky" (Jy) as a unit for spectral irradiance. There is a crater on the Moon named Jansky. The Karl G. Jansky Very Large Array is a major telescope in New Mexico.

Jansky died in 1950 at the age of 44. He passed away due to a heart condition. Today, his work is honored by the National Radio Astronomy Observatory. They award the Jansky Prize every year. A monument in Holmdel, New Jersey, marks the site of his original antenna. The sculpture is pointed toward the center of our galaxy. It honors the moment he discovered the sounds of the stars.