Skip to main content

Mysterious deep-space flashes repeat every 157 days

An artist's impression of a fast radio burst (FRB) reaching Earth, with colors signifying different wavelengths.
An artist's impression of a fast radio burst (FRB) reaching Earth, with colors signifying different wavelengths. (Image credit: Jingchuan Yu, Beijing Planetarium)

Astronomers have discovered an activity cycle in another fast radio burst, potentially unearthing a significant clue about these mysterious deep-space phenomena.

Fast radio bursts, or FRBs, are extragalactic flashes of light that pack a serious wallop, unleashing in a few milliseconds as much energy as Earth's sun does in a century. Scientists first spotted an FRB in 2007, and the cause of these eruptions remains elusive nearly a decade and a half later; potential explanations range from merging superdense neutron stars to advanced alien civilizations.

More than 100 FRBs have been discovered to date, and most of them are one-offs, flaring up just a single time (as far as we know). In January of this year, astronomers reported that one member of the "repeater" class, called FRB 180916.J0158+65, appears to exhibit a 16-day activity cycle: It fires off bursts for a four-day stretch, goes quiet for 12 days and then starts all over again.

Related: 8 baffling astronomy mysteries

The FRB 180916 was the first known to erupt in such a periodic way. And now scientists have spotted another.

Researchers monitored the known repeater FRB 121102 with the Lovell Telescope, a 250-foot-wide (76 meters) radio dish at Jodrell Bank Observatory in England, over the course of five years. They found strong indications of a 157-day activity cycle; 121102 seems to flare up for 90 days and then go silent for 67, the team reported in a new study.

It's unclear what's behind such cyclic activity, though scientists do have a few ideas. For example, periodic flare-ups could be caused by a wobble in the rotational axis of a highly magnetized neutron star known as a magnetar. Or they could be linked to the orbital motions of a neutron star in a binary system.

The wobble effects are expected to manifest over the span of a few weeks, study team members said. So they seem compatible with FRB 180916's 16-day cycle but not with that of FRB 121102, which is 10 times longer. But who knows? And there's also no guarantee that the same phenomenon is driving the periodicity of both repeating FRBs.

“This exciting discovery highlights how little we know about the origin of FRBs," study co-author Duncan Lorimer, the associate dean for research at West Virginia University, said in a statement. "Further observations of a larger number of FRBs will be needed in order to obtain a clearer picture about these periodic sources and elucidate their origin."

The new study, which was led by Kaustubh Rajwade of the University of Manchester in England, was published online this evening (June 7; June 8 United Kingdom time) in the journal Monthly Notices of the Royal Astronomical Society. You can read a preprint of it for free at (opens in new tab).

Mike Wall is the author of "Out There (opens in new tab)" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook

(opens in new tab)

OFFER: Save 45% on 'All About Space' 'How it Works' and 'All About History'! (opens in new tab)

For a limited time, you can take out a digital subscription to any of our best-selling science magazines (opens in new tab) for just $2.38 per month, or 45% off the standard price for the first three months.

Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at:

Mike Wall
Mike Wall

Michael Wall is a Senior Space Writer with (opens in new tab) and joined the team in 2010. He primarily covers exoplanets, spaceflight and military space, but has been known to dabble in the space art beat. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.

  • PhySciTech
    What would happen to Earth if our sun suddenly gave off this much energy? Instant vaporization would be my guess. What a way to go!!
  • Audubon Ballroom
    Base 10? Or SRB's?
  • Stephen J. Bauer
    I'll get excited when the pattern is deciphered.
  • uriz
    157 days? π =3.14 . 50π = 157
  • Darvon96
    157 is a prime number … just say'n.
  • bolide
    "Days" is a measurement based on Earth's rotations. It is meaningless anywhere else.
  • 157 Earth days could be another planet's day or year. Or, it could be the rotation of another star or other object.
  • Think twice
    I still think repeaters are a different phenomena than the one offs. Look at the available lightcurve images of repeaters in radio. And compare them with the one offs. The repeater lightcurve s I've seen do not look like the one offs. Also the single one offs are much longer and in different wavelengths than the repeaters. Consistently from the data I've seen.
  • Adrian Leatherland
    Is it possible that all FRBs are in the "repeater class" and some just have very long cycles? Given we can estimate the amount of energy and the distance to them, can we model the physics constraints of a "wobble" to estimate the upper and lower bounds of a cycle (i.e. try predicting when they will repeat)?
  • Think twice
    Admin said:
    Astronomers have discovered an activity cycle in another fast radio burst, potentially unearthing a significant clue about these mysterious deep-space phenomena.

    Mysterious deep-space flashes repeat every 157 days : Read more
    I still think single non repeating FRBs are a totally different phenomena. All the non repeaters have vastly different timescales, lightcurve profiles and frequency ranges than repeaters.