Radio Astronomy Intro
Disclaimer;
The Radio Astronomy section of the ASRAS website is under constant construction. So please be patient with us as we learn how to design effective web pages in wordpress.
Thanks – Martin Pepe, Pete Bonneau.
Images courtesy of NRAO, SARA, NSF, internet, MjPepe, etc.
Today, the fields of Astronomy & Radio are tightly linked. From the time of Galileo (1609) people have peered into the heavens looking through glass. In 1897 Marconi sent his first ‘wireless (radio) telegram’ message.
Who would have thought that a mere 31 years later (1934) these two disciplines would stumble across each other, and, create the most powerful tool with which to understand our very existence and place in the universe.
Galileo Galilei – Although NOT the inventor of the Telescope – He was the first to perfect it. Galileo discovered four of the many moons of Jupiter by using a telescope like this one (right). Its glass lenses were no better than that of the bottom of a common pop bottle. Today, on a clear night, you can see the 4 Galilean moons {Io, Europa, Ganymede, Callisto} by using a pair of simple binoculars from Walmart.
Astronomy & Radio
Why Radio?
Only VISIBLE & RADIO waves make it all the way to the ground,
X-Rays, UV, IR, etc. get absorbed by our atmosphere.
With Lake Ontario to our North, and Lake Erie to our West, WNY easily makes the cloudiest area of the country (more partly cloudy days than Seattle)!
You cannot use an optical telescope when it’s cloudy, so…..
Switch to a longer Wavelength 😊
The Longer Radio Waves go right through clouds & moisture.
A Brief History
In 1928 Karl Jansky started working on a long wire antenna for Bell Laboratories to create a transatlantic Radio Telephone Service to Europe using the 20.5 MHz band.
Results were erratic as they encountered a ‘hiss’ that repeated exactly every 23 hrs. & 56 min (NOT 24 hrs.). Furthermore, the baseline noise level, repeated & tracked each month in every year.
Unknowingly, they were receiving celestial radio emissions from planets, the Sun, stars, galaxies, etc. The reason for the 23 hrs. 56 min. repeat, was that’s exactly how long it takes for the Earth to make one complete revolution (1 day) on its axis (not 24 hrs.).
Additionally, the baseline repeat each month of the year, was that their antenna was pointed out to a different location in deep sky (for the same reason you don’t see the constellation Orion in the summer & Scorpius in the winter), and they were also receiving synchrotron radiation from the cosmic ray background (CMB) .
A bright grad student, and avid ham radio operator, Grote Reber wanted to join this team to continue this work. But alas, the project was canned & he was not hired. Undaunted, Grote built a dish antenna in his mother’s back yard of suburban Chicago, then added a chart recorder to give himself a hardcopy record of his experiments.
He had to switch to evening work, as there was too much interference (RFI) during the day from car ignitions, and industry.
I’m sure he raised some suspicions from the neighbors & government as the year was 1943! But it helped to put Ham Radio research on the map during and after WW II.
Book – Cosmic Noise – >>
A History of early Radio Astronomy
1928: Karl Jansky – Bell Laboratories
A Light Wave is a Light Wave no matter how LONG
Light, X-Rays, Radio, etc. are all part of the Electro-Magnetic (EM) Spectrum of energy. Light has two major properties, Particles (photons) and Wavelength (waves – like waves crashing periodically on a beach).
The radio that you listen to, the microwave that cooks your dinner, the color of a red rose, even the X-Rays used in the hospital when you break a leg are all the SAME, they only vary in length. Your eyes, then, are really tiny radio receivers.
Regardless of wavelength all EM waves travel at the same speed 186,000 miles per second! How many seconds in a year? (31,536,000) x 186,000 = 1 LIGHT YEAR
Our nearest neighbor, the Andromeda Galaxy is about a mere 2.6 million light-years away.
Complicated molecules and compounds like proteins, sugars, phosphates, and 22 Amino Acids (ALL those things that go into your RNA & DNA) have been found in DEEP SPACE with a RADIO TELESCOPE!
Life (as we know it) depends on WATER and its all-over outer space. (the water molecular resonates at 22 GHz.) FOUND with a Radio Telescope!
WE ARE MADE OF STAR STUFF!!
A Brief History:
A History of early Radio Astronomy
1928: Karl Jansky – Bell Laboratories
A PIXEL is a PIXEL
- Except when you don’t have enough of them!
A pixel is the smallest piece of a digital photo describing the picture you’re looking at. We’ve all been disappointed by a grainy photo (usually the more pixels the better). A typical digital camera has 10 to 40 Mega Pixels (million). This is also what drives HD video television having finer detail (1080 or 4K).
A radio astronomer takes a ‘picture’ of the ‘radio sky’ one pixel at a time, then re-assembles them in a computer to create an ‘image’. The example shown (upper right) is a ‘wire frame’ model of two peaks with a shallower one in between.
The computer can then apply a ‘false color’ to the data to make it a appear as a ‘visual image’.
The Green Bank Radio Telescope (right) is 100 x 110 Meters (two soccer fields) & is the heaviest moving object on Earth, at over 16.7 Million lbs.
Radio Telescopes
LCRT (future)