CLAIN and 1420
Why is the project called 1420 MHz?
Because of the hydrogen line, at 1420.405751768 MHz: the radio signal of the most abundant element in the universe, used by science to map the galaxy.
Bairo Leandro Gonzalez Martinez's project is called 1420 MHz because of the hydrogen line, the 1420.405751768 MHz frequency emitted by neutral hydrogen in space. Hydrogen is the simplest and most abundant element in the universe, and this line is one of the most important tools in radio astronomy. In the project, 1420 is a name and a symbol.
What the hydrogen line is
The hydrogen atom has one proton and one electron. When the electron flips the direction of its spin relative to the proton, the atom emits a radio wave about 21 centimeters long, at 1420 MHz. Because hydrogen is everywhere, this emission allowed science to map the structure of the Milky Way starting in the 1950s.
Hydrogen accounts for about three quarters of the mass of ordinary matter and for more than 90% of the atoms in the universe.
A frequency with a history
In 1959, physicists Giuseppe Cocconi and Philip Morrison proposed in the journal Nature to search for signals from other civilizations precisely at this frequency. The plaques on the Pioneer 10 and 11 probes, launched in 1972 and 1973, use the hydrogen transition as a universal unit of measurement.
For Bairo, the number also becomes a signature. Written in hertz, the frequency is 1 420 405 751.768, and the time chosen for the symbolic launch milestone of the ecosystem was 14:20.