An artist's depiction of neutron star merger. Credit: NSF / LIGO / Sonoma State University / A. Simonnet

Scientists announced today they've detected the collision of two neutron stars 130 million years ago. It's the first time one of the massive mergers has been witnessed, and that light detected with telescopes has been combined with gravitational waves detection to observe a cosmic event.

What it means: "This result provides definitive evidence for the first time that heavy elements like platinum and gold, are produced in these collisions," David Reitze, executive director of the LIGO Laboratory, whose founders will collect the Nobel Prize in physics this year. The so-called "multi-messenger astronomy" allows researchers to view events in both light and sound, and will be used to better understand the structure of stars, the rate of expansion of the universe and other fundamental questions in physics.

What they saw: 130 million years ago, two dense neutron stars — with masses 1.6 and 1.1 times those of our sun crammed into about 10-mile-wide spaces — merged. The highly energetic event sent ripples across space and time that physicists working with the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo detectors observed on Aug. 17, 2017. The collision, which occurred relatively close to Earth, released high-energy, gamma-ray light that was also then seen by 70 optical, X-ray, radio, ultraviolet, infrared, and gamma-ray telescopes around the world and in space over the following days.

What's next: Dozens of papers are being published today by the more than 3500 researchers involved in the work. The LIGO and Virgo detectors have finished their current run and will be offline for a year while researchers try to optimize them. "[They are] currently working at a fraction of their sensitivity. We expect to increase the overall network sensitivity by about a factor of 2," said LIGO spokesperson David Shoemaker. That would open up 8 times more space for surveying and, they hope, observing other events like supernovae.

Go deeper: Quanta's Katia Moskvitch has the play-by-play of the detection.

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Robert Mueller speaks out on Roger Stone commutation

Former Special Counsel Robert Mueller testifies before the House Permanent Select Committee on Intelligence on Capitol Hill on Wednesday July 24, 2019. Photo: The Washington Post / Contributor

Former special counsel Robert Mueller responded to claims from President Trump and his allies that Roger Stone was a "victim" in the Justice Department's investigation into Russian interference in the 2016 election, writing in a Washington Post op-ed published Saturday: "He remains a convicted felon, and rightly so."

Why it matters: The rare public comments by Mueller come on the heels of President Trump's move to commute the sentence of his longtime associate, who was sentenced in February to 40 months in prison for crimes stemming from the Russia investigation. The controversial decision brought an abrupt end to the possibility of Stone spending time behind bars.

Trump dons face mask during Walter Reed visit

Trump wearing a face mask in Walter Reed National Military Medical Center on July 11. Photo: Alex Edelman/AFP via Getty Images

President Trump wore a face mask during his Saturday visit to Walter Reed National Military Medical Center, according to AP.

Why it matters: This is the first known occasion the president has appeared publicly with a facial covering as recommended by health officials since the coronavirus pandemic began, AP writes.

Updated 10 hours ago - Politics & Policy

Coronavirus dashboard

Illustration: Sarah Grillo/Axios

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