Construction is currently underway in South Africa and Australia for the Square Kilometre Array (SKA), a massive radio telescope poised to revolutionize our understanding of the cosmos. Its primary target?
Neutral hydrogen (H1).
To find it, astronomers tune their "dials" to the 21-centimeter line. To explain what the heck this actually means, we reached out to Dr. Nicole Gugliucci of Saint Anselm College.
According to Gugliucci, every element emits specific signatures. The 21cm line is the specific wavelength of light emitted by neutral hydrogen atoms.
Light travels in waves, just like the radio signals from NHPR are sent to homes and cars. A "wavelength" is simply the distance between the peaks of those waves.
While a lightbulb emits a messy mix of all visible colors, the 21cm signal acts like a laser: it is a precise, narrow frequency that radio astronomers can lock onto with extreme accuracy.
The Square Kilometre Array isn't just looking at stars; it’s listening to the "hum" of the hydrogen that connects them. By mastering the 21cm line, we are finally building a complete map of the universe’s history.
If you have questions about the night sky, shoot us an email at cosmic@nhpr.org.
