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Cosmic Space

See our galaxy’s black hole — and hear what’s next

After years of observation and weeks of rumor-mill rumblings, astronomers today unveiled their first image of the supermassive black hole at the center of our own Milky Way galaxy, Sagittarius A*.

Technically, the picture from the Event Horizon Telescope project doesn’t show light from the black hole itself. After all, a black hole is a gravitational singularity so dense that nothing, not even light, can escape its grip. Rather, the picture shows the “shadow” of a black hole, surrounded by the superheated, glowing gas that surrounds it.

And technically, the picture may not match what folks might see with their own eyes up close. Rather, the readings come from eight observatories around the world that combined their observations in radio wavelengths.

Nevertheless, the new view of Sagittarius A*, or Sgr A* for short (pronounced “sadge-ay-star”), serves to confirm in graphic terms what astronomers have long suspected: that our galaxy, like many others, has a supermassive black hole at its heart.

Today’s revelations follow up on the Event Horizon Telescope’s first-ever black hole image, which was released in 2019 and showed the supermassive black hole at the center of M87, an elliptical galaxy about 55 million light-years away.

Sgr A* is much closer — a mere 27,000 light-years from Earth, in the constellation Sagittarius. But there’s nothing to fear from this black hole: It’s relatively quiescent, in contrast to the galaxy-gobbling behemoths that are standard science-fiction fare.

Our galaxy’s black hole is thought to hold the mass of 4 million suns within an area that’s roughly as big around as Mercury’s orbit. Checking those dimensions against the image data serves as a test of relativity theory. Spoiler alert: Albert Einstein was right … again.

“We were stunned by how well the size of the ring agreed with predictions from Einstein’s theory of general relativity,” EHT project scientist Geoffrey Bower said in a news release. “These unprecedented observations have greatly improved our understanding of what happens at the very center of our galaxy and offer new insights on how these giant black holes interact with their surroundings.”

The EHT’s findings about Sgr A* are the subject of a special issue of The Astrophysical Journal Letters — and to whet your appetite for all that reading material, here are three videos that summarize the past, present and future of black hole imaging:

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GeekWire

Astronomers make an Earth Day plea to rein in satellites

Astronomers have issued an Earth Day call for environmentalism to be extended more fully to the final frontier, and for companies such as SpaceX and Amazon to dial back their plans for mega-constellations.

Among the authors of today’s commentary in the journal Nature Astronomy is Meredith Rawls of the University of Washington.

Astronomers have been raising concerns about the impact of having thousands of satellites in low Earth orbit for years, starting with SpaceX’s launch of the first operational satellites for its Starlink broadband constellation in 2019. Rawls and the other authors of today’s commentary stress that they aren’t just worried about interference with their astronomical observations, but are also concerned about the broader impact on appreciation of the night sky.

“We need all hands on deck to address the rapidly changing satellite situation if we can hope to co-create a future with dark and quiet skies for everyone,” Rawls, a research scientist with the Vera C. Rubin Observatory and UW’s DIRAC Institute, said in a news release.

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Universe Today

Hubble astronomers spot the farthest star ever seen

A star that sounds as if it came from “The Lord of the Rings” now marks one of the Hubble Space Telescope’s farthest frontiers: The fuzzy point of light, known as Earendel, has been dated to a mere 900 million years after the Big Bang and appears to represent the farthest-out individual star seen to date.

Based on its redshift value of 6.2, Earendel’s light has taken 12.9 billion years to reach Earth, astronomers report in this week’s issue of the journal Nature. That distance mark outshines Hubble’s previous record-holder for a single star, which registered a redshift of 1.5 and is thought to have existed when the universe was 4 billion years old.

The newly reported record comes with caveats. First of all, we’re talking here about a single star rather than star clusters or galaxies. Hubble has seen agglomerations of stars that go back farther in time.

“Normally at these distances, entire galaxies look like small smudges, with the light from millions of stars blending together,” lead author Brian Welch, an astronomer at Johns Hopkins University, said today in a news release. “The galaxy hosting this star has been magnified and distorted by gravitational lensing into a long crescent that we named the Sunrise Arc.”

A close look at the arc turned up several bright spots, but the characteristics of the light coming from Earendel pointed to a high redshift, which translates into extreme distance. The higher the redshift, the faster the source of the light is receding from us in an ever-more-quickly expanding universe.

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GeekWire

Student wins top prize for gravitational wave work

Christine Ye, a senior at Eastlake High School in Sammamish, Wash., has won the top award in the nation’s oldest and most prestigious competitions for science students, thanks to her research into the mysteries of black holes and neutron stars.

“I’m totally in shock,” the 17-year-old told me after winning the $250,000 first-place award in the 2022 Regeneron Science Talent Search. “It feels amazing.”

Ye was among 40 finalists honored on March 15 in Washington, D.C., during a live-streamed ceremony that was emceed by “Saturday Night Live” cast member Melissa Villaseñor. More than $1.8 million in all was awarded to the finalists, who were evaluated on the basis of their projects’ scientific rigor and their potential to become scientific leaders.

Ye’s award-winning research is based on an analysis of readings from the Laser Interferometer Gravitational-wave Observatory, and addresses one of LIGO’s most puzzling observations.

In 2019, researchers at LIGO and at Europe’s Virgo gravitational-wave observatory detected ripples in spacetime that were caused by the collision of a black hole and a mystery object that was 2.6 times as massive as our sun. The object’s size fell into a “mass gap” between the heaviest known neutron star and the lightest known black hole.

The analysis conducted by Ye and her co-author, Northwestern University postdoctoral fellow Maya Fishbach, determined that rapidly spinning neutron stars could get as massive as the mystery object. Their study will be the subject of a presentation next month in New York at a meeting of the American Physical Society.

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GeekWire

Radio astronomy director cuts through the static

There are plenty of astronomers who worry that the thousands of satellites that are being launched into low Earth orbit for global broadband internet access will cast a pall over their scientific observations. But Tony Beasley, director of the National Radio Astronomy Observatory, says the future looks bright.

And he means that in a good way.

It’s not just that he’s confident astronomers will deal with the challenges posed by potential interference from all those satellites — including the latest batch of 47 Starlink satellites, which were built at SpaceX’s factory in Redmond, Wash., and sent into orbit today from Florida atop a SpaceX Falcon 9 rocket.

“We will find a solution,” Beasley told GeekWire. “We’re not going to be the ones that cause all of the concerns here for SpaceX. It could be that our optical [astronomy] friends will do that, but that’s OK.”

Beasley, an Australia native who’s headed the National Science Foundation’s leading center for radio astronomy for the past decade, is also optimistic about the prospects for the NRAO’s next giant leap: the Next Generation Very Large Array.

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GeekWire

Astronomers set up center to save the sky from satellites

The International Astronomical Union is heading up the creation of a new center to deal with the complications created by broadband satellite constellations like SpaceX’s Starlink and Amazon’s Project Kuiper.

The IAU Center for the Protection of the Dark and Quiet Sky From Satellite Constellation Interference will be co-hosted at the National Science Foundation’s NOIRLab in Arizona and the SKA Observatory’s offices at Jodrell Bank in Britain.

“The new center is an important step towards ensuring that technological advances do not inadvertently impede our study and enjoyment of the sky,” IAU President Debra Elmegreen said today in a news release.

Former IAU General Secretary Piero Benvenuti, the center’s director, said the memorandum of understanding creating the center was signed just a day earlier, and a website for the project hasn’t yet been established.

But the University of Washington’s Institute for Data Intensive Research in Astrophysics and Cosmology, or DIRAC, is already getting a head start on one of the center’s missions — cataloging astronomical images with satellite streaks so they can be made available for analysis.

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GeekWire

Webb Telescope reaches its final destination

The $10 billion James Webb Space Telescope successfully fired its thrusters today to put it in position at the destination where it’s expected to probe the mysteries of the universe for years to come.

The nearly five-minute firing at 11 a.m. PT sent JWST into its prescribed orbit around a balance point known as L2, a million miles beyond Earth. It’s a point where the gravitational pulls of the sun and the Earth align to keep spacecraft in a relatively stable position, minimizing the need for course corrections.

Today’s maneuver came 30 days after the telescope’s Christmas launch from the European Arianespace consortium’s spaceport in French Guiana. NASA is playing the lead role in the project, in partnership with the European Space Agency and the Canadian Space Agency.

“Webb, welcome home!” NASA Administrator Bill Nelson said in a statement. “Congratulations to the team for all of their hard work ensuring Webb’s safe arrival at L2 today. We’re one step closer to uncovering the mysteries of the universe. And I can’t wait to see Webb’s first new views of the universe this summer!”

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GeekWire

Astronomers rejoice after Webb Telescope unfolds mirror

Two weeks after its Christmas launch, the James Webb Space Telescope finished unwrapping itself today, delighting astronomers in the process.

The deployment of JWST’s 18-segment, 21.3-foot-wide primary mirror marked the end of the riskiest portion of the $10 billion telescope’s mission.

It’s still more than 300,000 miles from its destination, a gravitational balance point known as L2 that’s a million miles from Earth. It still has to fine-tune the orientation of the mirror’s gold-and-beryllium segments, and cool its instruments down to a temperature just a few degrees above absolute zero. But mission controllers at the Space Telescope Science Institute were able to tick off nearly 300 potential points of failure without a hitch.

“We have a fully deployed JWST observatory,” Northrop Grumman’s Paul Reynolds, who led the mission’s deployment operations team, declared during a widely watched webcast.

JWST is designed to be 100 times more sensitive than the 32-year-old Hubble Space Telescope, which is near the end of its longer-than-expected life. Once JWST begins science operations, as early as May, it should bring new revelations about mysteries ranging from the habitability of alien planets, to the nature of black holes and quasars, to the origins of the universe.

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GeekWire

Webb space telescope’s launch makes Christmas merry

The most expensive telescope in the known universe has begun its journey to a vantage point a million miles from Earth with its launch from French Guiana.

Today’s liftoff of an Ariane 5 rocket from the European Space Agency’s South American spaceport, coming at 9:20 a.m. local time (4:20 a.m. PT), was just the first step of what’s expected to be a monthlong trip for NASA’s $10 billion James Webb Space Telescope.

“Everything fell together on this Christmas Day to send a new present to the world’s astronomers,” NASA launch commentator Rob Navias said.

Flight controllers broke into applause when the telescope separated from the Ariane 5’s second stage. “Go Webb!” range operations manager Jean-Luc Voyer cried.

NASA Administrator Bill Nelson noted that the James Webb Space Telescope is designed to look back to an age when the first stars and galaxies formed, more than 13.5 billion years ago.

“It’s a time machine,” Nelson said. “It’s going to take us back to the very beginnings of the universe. We are going to discover incredible things that we never imagined.”

JWST is due to settle into a region of space known as the Sun-Earth Lagrange Point 2, or L2, where the gravitational pulls of Earth and the sun align to help keep spacecraft in a stable position within Earth’s shadow. Along the way, the telescope will have to unfurl its sunshield and its segmented mirror in a process that’s said to have 344 potential single points of failure.

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GeekWire

High hopes are riding on space telescope’s risky launch

The launch of NASA’s $10 billion James Webb Space Telescope from French Guiana could mark a triumph in a tale that thousands of astronomers have been following for a generation. Or it could result in the deepest tragedy.

Either way, the climax is due to unfold beginning on Christmas morning — making for a plot worthy of a holiday movie.

“I’ve been waiting 23 years for this telescope to launch,” University of Washington astronomer Eric Agol told GeekWire.

Agol has been waiting so long that the focus of his research changed completely during the wait. Back in 1998, when the Next-Generation Space Telescope was still on the drawing boards, he was studying gravitationally lensed quasars.

“I was doing some science at the time with ground-based telescopes and, and specifically the Keck Telescope up in Hawaii,” Agol said. “We were spending half a night looking at distant quasars, and then we calculated that with the James Webb Space Telescope, it would take a few milliseconds to do the same observation.”

Now he’s studying planets beyond our own solar system — with an intense focus on TRAPPIST-1, a potentially habitable planetary system 39 light-years from Earth. It’s a testament to the telescope’s versatility that it promises to have just as dramatic effect on that project.

“James Webb is just going to give phenomenal data on this system of transiting planets,” Agol said. “Each of the transits will yield spectral information if there are any signs of atmospheres in these planets. This is the first time where we have a really good chance of probing atmospheres on potentially Earthlike planets.”

But first, the telescope has to get settled at its location in deep space, a million miles from Earth, at a gravitational balance point known as Sun-Earth L2.