‘She was a radio astronomer, meant to discover new stars’ by Maria Cristina Rodriguez Rivero

It is interesting how a pen, connected to a bulky electronic machine scrubbing peaks and valleys on a continuous roll of paper can become so important. Jocelyn was taking care of this complex machinery as if it was a precious friend. This friend was going to help her to see far away in the skies, to peak into the intricate Universe, farther than the Moon or the Sun, well away from the Solar System, so far that we refer distances not in miles any more, not in trillions of miles but in hundreds and thousands of light years. To see that far we need cleverly designed machines as the one Jocelyn was working side by side with. It was a strange piece of equipment that some colleagues and she had been building for the past two years in the Radio Astronomy Observatory in Cambridge.

It was a radio telescope, similar to the ones in the movie Contact that were tracking outer space radio signals (you should see the movie if you haven’t done so!). But Jocelyn’s radio telescope was different in design. It wasn’t a big antenna as those we see these days but it had miles of wires and wooden posts, interconnected in a complex manner. The more technical name for this particular telescope was Interplanetary Scintillation Array because actually Jocelyn wanted to study something called scintillation. Scintillation is similar to what happens when stars flicker as seen from Earth. That twinkling happens when light from outside the solar system crosses our atmosphere and gets distorted. The scintillation Jocelyn wanted to study happens when a particular type of signals cross the solar winds, instead of the Earth atmosphere. These signals come from quasars, discovered not many years before and therefore, a trending topic in research at the time. Quasars are a type of black hole (the most powerful objects we know of). They emit huge amounts of energy, including radio signals that reach Earth.

A radio telescope works like your radio at home. It collects signals of the type we called “radio” with its antenna or antennae, depending on the design. Radio signals are similar to the signals that you see with your eyes when you look at the stars (the visible stars) or at things around us, but our eyes are not made to “see” radio signals. Think of radio signals as a colour but far away from violet, blue, green, yellow or red. We have devised ways to translate those “colours” into other signals that we can see or hear. We can convert them into audio signals as those heard with a conventional radio device and also, as radio telescopes do, we can translate them into numbers to be stored and analysed with the help of a computer. Back in the 60s Jocelyn’s telescope converted them into a mechanical signal that moved a pen on a continuous roll of paper Jocelyn could then analysed. These days computers help us in examining those data but Jocelyn had no computer then! She had to analyse kilometres of paper.

Discoveries happen in the most different ways, let’s see how it happened to be for Jocelyn. Imagine her, checking and checking thoroughly the lines drawn on the paper and annotating things here and there. One day, imagine her entertainingly staring (or maybe with tired eyes already) at some ink strokes, showing a different pattern than the one she was expecting, like some fast pulses (imaging if monitoring the heartbeat, finding some fast beats at a different frequency and back to normal, well, something similar). In her mind something lit on. She recalled seeing something similar before, or maybe not? She then came back pages of her annotations and ran through the roll of paper with her finger. Then some more of those particular “beats” were there, interestingly coming from the same part of the sky. It must have got very intriguing.

But before telling her colleagues she wanted to be sure those peaks were produced by signals coming from outside the Solar system, at least from outside Cambridge, outside Earth! She checked the telescope, looked for radio signals coming from places nearby and nothing. It seemed to genuinely come from outer space. She shared then this information with her colleagues and she checked again, more rolls of paper, new ones, old ones, and then she realised that more of those peaks with similar patterns were happening in other regions of the Universe.

Now things are getting even more interesting! Then you have to share this with other colleagues around the world and check with more radio telescopes, all pointing to the same areas in the sky, looking for the cause of those signals, to check their consistency. It is critical to have consistent results in Science! And then it was confirmed: Jocelyn and her colleagues had discovered a new object in the sky. Wow! I wonder if that feels a bit like discovering a new planet in the Solar System, like when Sir William Herschel, with the invaluable help of his sister Caroline Herschel, discovered the first planet in the recorded History of Humankind: Uranus. Imagine how they should have felt. Back in the 18^th century then. Maybe Vera Rubin in the 20^th century this time, had also a similar feeling when creating a new field of astronomy by discovering dark matter. So many things going on in this Universe and so many things we could talk about!

In any case, after Jocelyn’s discovery we wanted to know more about the place from which those signals were emanating and we discovered that the objects creating those strokes are very compact rotating old stars made of particles called neutrons. Imagine now stars even more massive than the Sun. Some of them, when reaching the end of their lives, explode and in the centre of the explosion a small –about 20 km in diameter- but very dense material remains. It is so compact that a spoon of it would weight about a billion tones on Earth. They spin very fast and eject energy in the form of radio waves such as those which Jocelyn could measure. They spin in a very regular manner (like a high-speed lighthouse) so they are used as celestial references for maps of the Universe and for very precise clocks too.

And you’re now wondering about Jocelyn and what she did after such a discovery, am I right? Maybe you could ask her one day… I will only tell you that she is still deciphering secrets of the stars! Interestingly she also works in promoting equity in Science and encouraging girls to pursue Science careers because no matter your gendre, the colour of your skin, height or any other feature you may think of, all of us can become star discoverers or anything we like as long as we work hard!

And remember, next time you look at the stars pulsars are up there even if we don’t see them with our naked eyes, sending us a bit of their essence in the form of pulsed radio waves.