What do you get when you put a one-meter parabolic dish, an SDR, a Raspberry Pi, and an H1-LNA for 21 cm emissions together? The answer is: a radio telescope that can track hydrogen in the Milky Wa… ...

The 21-cm emission isn't particularly bright, but because there is so much hydrogen out there, the signal is easy to detect. And wherever there is matter, so too is the hydrogen line.

I'm writing up a report about 21cm-line radio ... How to calculate the energy of the hydrogen line. Thread ... I'd really like to show some sort of derivation for the prediction of the 21-cm line.

OBSERVATIONS have been made at the Kootwijk Station of the Dutch Organization for Radio Astronomy, in order to ascertain whether hydrogen radiation of 21 cm. wave-length, detected in the galaxy ...

It was first determined to be the 21-centimeter line or hydrogen line in 1951, and the first map of neutral hydrogen in the Milky Way was completed soon after.

The signal was detected by a unique wavelength known as a “21-centimeter line” or the “hydrogen line,” which is reportedly emitted by neutral hydrogen atoms.

While stars are made of hydrogen – so this might not seem too weird – this is an emission line we were not expecting to see this early in the universe. "This is WILD.