Jocelyn Bell Burnell

Jocelyn Bell Burnell discovered pulsars as a PhD student.Credit: David Hartley/Shutterstock

Fifty years after discovering pulsars — compact rotating stars that emit beams of radiation — astrophysicist Jocelyn Bell Burnell has been awarded one of the most lucrative prizes in science: a US$3-million Breakthrough prize. Thought by many to have been snubbed for a Nobel prize for the discovery1, Bell Burnell, 75, has been recognized by the Breakthrough committee with a special award in fundamental physics for both her scientific achievements and her “inspiring leadership” over the past five decades.

“I cannot think of a more deserving scientist to win this prize,” says Chiara Mingarelli, an astrophysicist at the Flatiron Institute in New York City. “In addition to being both a pioneer and a giant in the field, Bell Burnell is the highest calibre role model — a champion for women in science, who speaks out against the many inequities faced by women in STEM [science, technology, engineering and mathematics] fields.”

The Breakthrough prizes were launched in 2012 and are funded by entrepreneurs including Google co-founder Sergey Brin and Facebook chief Mark Zuckerberg. Awarded in fundamental physics, life sciences and mathematics and each worth $3 million, they are usually handed out in December, based on selections made after an open nomination process. But the selection committee can decide to make special awards, bypassing the standard nomination procedure, to those they deem particularly deserving. Previous special awards have been given to Stephen Hawking, the Laser Interferometer Gravitational-Wave Observatory (LIGO) collaboration for the discovery of gravitational waves, and seven CERN scientists who co-ordinated the hunt for the Higgs boson.

Mystery smudges

Pulsars are small, dense stars, consisting mostly of neutrons, that rotate at a precise rate, emitting radiation as they spin. In 1967, Bell Burnell, then a PhD student at the University of Cambridge, UK, under astronomer Antony Hewish, was analysing hundreds of metres of chart paper with data collected by the roughly 2-hectare array radio telescope in Cambridge when she noticed some mysterious recurring smudges. She was able to characterize these as signs of radio pulses emanating from a spinning star: the pulsar. “The discovery is a testament to her curiosity, her determination and her creativity,” says Mingarelli.

In 1974, Hewish shared the Nobel Prize in Physics with fellow radio astronomer Martin Ryle, for pioneering research in astrophysics. Hewish was cited for his “decisive role in the discovery of pulsars” — while Bell Burnell was overlooked. Bell Burnell herself has previously stated that she does not mind the oversight because she understands that Nobel prizes are not usually awarded to research students.

Bell Burnell, now at the University of Oxford and the University of Dundee, was “totally surprised” to learn about her selection for the special Breakthrough prize. “For once in my life, I was speechless,” she says. She is already in discussions with the national physics institutes in the United Kingdom and Ireland about using the prize money to create PhD studentships for people from under-represented groups in science. “Diversity is very important,” says Bell Burnell. “This also recognizes that I did my most important work as a student.”

Pulsar navigation

The effects of Bell Burnell’s discovery still ring out half a century on, notes Mingarelli. For instance, earlier this year, NASA scientists demonstrated the feasibility of using pulsars to navigate, with their SEXTANT experiment (Station Explorer for X-ray Timing and Navigation Technology), on board the International Space Station. The idea is that future robotic spacecraft could use the clockwork-like arrival times of X-rays emitted from pulsars to triangulate their locations.

Meanwhile, Mingarelli and other astronomers are monitoring bursts from an array of pulsars scattered around the Galaxy, looking for slight shifts in their arrival times at Earth2. Any such delays would indicate that the pulsar had been jostled by a passing gravitational wave — a ripple in space-time set off by cataclysmic events such as the merger of supermassive black holes, objects that lie at the hearts of galaxies that weigh in at millions or even billions of times the mass of the Sun. (The LIGO observatory, by contrast, detects gravitational waves that are released when much smaller objects, such as stellar-mass black holes, collide.) Astronomers expect to use the array to make the first detection of gravitational waves that have been generated by such a process in the next few years. “Pulsars can be used to turn a galaxy into a giant gravitational-wave detector,” says Mingarelli. “So you can see the far-reaching results of Bell Burnell’s work.”

Brian Keating, an astrophysicist at the University of California, San Diego, who this year published a book criticizing the Nobel committee’s selection processes, says that this Breakthrough award “rights past injustices and properly honours the pioneering and pivotal contributions of a scientist who opened a new window on the cosmos”.

Keating adds that the prize “should also be seen as a shot across the bow of the Nobel-prize committee”. He notes that Bell Burnell could still be awarded the Nobel prize, without violating any of the Nobel Foundation’s rules. “Doing so immediately would also send an inspirational message to scientists — male and female, young and old — that it is the discovery itself, not the gender, prestige or age of the discoverer, that really endures.”