A space telescope that observes stars in the Milky Way as they appear today reveals what happened to the galaxy when it was just a couple of billion years old, and an upcoming data release will allow astronomers to peek into an even more distant past.
The European Space Agency’s Gaia mission is not a household name like the Hubble Space Telescope or the James Webb Space Telescope. Yet the mission currently produces the most scientific papers and, as Milky Way researchers would tell you, has enabled unprecedented leaps in our understanding of the galaxy’s history.
Gaia works differently than Webb or Hubble. Instead of observing the universe one fascinating distant object at a time, Gaia scans the whole sky over and over again. The flying-saucer-like telescope, nestled in Lagrange Point 2 some 930,000 miles (1.5 million kilometers) from Earth, observes 2 billion of the brightest stars in the sky, its view free from the distorting effects of Earth’s atmosphere that plague ground-based telescopes’ observations.
Unlike Hubble and Webb, Gaia doesn’t focus on capturing awe-inspiring images that reveal every detail of those distant stars and galaxies. Instead, the probe concentrates on a few basic parameters: the stars’ distance from Earth, the speed at which the stars move through space, and the direction of their motion as it appears on the plane of the sky and in three dimensions.
Because objects in space follow the laws of physics, scientists can model the trajectories of those stars billions of years into the past and future, unpicking the events that shaped the galaxy’s evolution. A discipline known as galactic archaeology has grown immensely since Gaia’s launch in 2013, and the new data release coming Monday (June 13) is set to supercharge the research.
“We are still trying to unravel the details of the Milky Way’s origins,” Anthony Brown, an astronomer at Leiden University in the Netherlands and chair of the Gaia Data Processing and Analysis Consortium, told Space.com. “With the new release, we should be able to do it even better, because we are getting some new data.”
Trajectories of stars in the Milky Way galaxy over the next 400,000 years based on measurements by the European Gaia mission. (Image credit: ESA/Gaia/DPAC)
Getting to know the stars
Those new data contain what astronomers call astrophysical parameters. Derived from the light spectra of the observed stars (essentially the fingerprints of how stars absorb light), the astrophysical parameters reveal ages, masses, brightness levels and, in some cases, detailed chemical compositions of the observed stars.
“You really get to know the stars,” Jos de Bruijne, Gaia project scientist at ESA, told Space.com. “It’s like you have an anonymous group of people and now you get to meet every one of them. You get to know their names and how old they are and where they came from.”
The group of stars that astronomers “get to meet” thanks to the June 13 data release consists of half a billion individual objects, one-quarter of the stars Gaia observes. This information will help astronomers refine the order of events that shaped the Milky Way and “really untangle its formation history,” Brown added.
The Milky Way is devouring small galaxies in its orbit. (Image credit: ESA/Gaia/DPAC)
What we already know
Astronomers think the Milky Way started forming only about 800 million years after the Big Bang and went through a 1 billion to 2 billion-year period of intense formation, Brown said. This formation period involved many collisions with other galaxies, which gradually built up the Milky Way into what we see today: a massive spiral galaxy encompassing 200 billion stars. (Gaia sees only about 1% of them.)
In the previously released Gaia data, researchers found imprints of those early collisions in the form of waves that still ripple through the galaxy, affecting the motion of stars. The most significant of these collisions was with a galaxy called Gaia Enceladus. That galaxy was about four times smaller than the Milky Way when the two crashed about 10 billion years ago. The collision, Gaia data revealed, gave rise to the Milky Way’s halo, the sphere of thinly dispersed stars enveloping the galaxy’s much more massive disk.
“At the moment, we think that [the collision with Gaia Enceladus] was the last significant merger that the Milky Way underwent,” Brown said.
(Image credit: ESA)
Tracing the “smallest building blocks”
Among the astronomers awaiting the June 13 data release is Eduardo Balbinot, a postdoctoral researcher in astrophysics at the University of Groningen in the Netherlands. Balbinot is interested in more modest collisions with what he calls the “smallest building blocks” of the galaxy: globular clusters, ancient groupings of stars devoured by the Milky Way over the eons.
“[The globular clusters] are special, because when they dissolve in these accretion events, they’re torn apart,” Balbinot said. “But they continue living as coherent groups of stars in the sky as what we call stellar streams.”
These stellar streams have been notoriously hard to detect, but Balbinot thinks the new Gaia data will usher in a breakthrough in this endeavor.
“There will be an additional velocity component [in the new data set], the so-called radial velocity — how fast the stars move towards or away from us,” Balbinot said. “Gaia measured some of those before, but the new sample will be 10 times bigger. It’s bigger than anything before.”
In those motions of stars, astronomers will be able to distinguish groups of stars that move through the galaxy in sync. By combining this information with data about the chemical compositions of stars (stars that arrived from other galaxies have distinct chemical profiles), astronomers will be able to peek into the galaxy’s past like never before.
“That’s one of the exciting things that you can do with Gaia data,” Balbinot said. “You can find these groups of stars that move similarly and basically reconstruct from where they came from and which building block brought them into the Milky Way. Then, you can ultimately answer the question of how the Milky Way formed.”
What happens on the galaxy’s edge
Balbinot hopes the new data will enable astronomers to look for remnants of globular clusters much farther away from Earth than was possible before, in the very outskirts of the galaxy, where the galactic halo meets intergalactic space.
“The new data set will contain a small subset of data on variable stars, which are very bright, and because they are so bright, we can see them all the way to the edge of the Milky Way,” Balbinot said. “They are basically the most distant stars that we will ever be able to detect within our Milky Way galaxy. And that is really exciting, because it really is an uncharted territory.”
Balbinot said the variable stars might reveal leftovers from ancient collisions with globular clusters scattered across the galactic halo, in the form of spherical “shells.” Analysis of these shells can reveal a lot about the anatomy of the events that gave rise to them billions of years ago.
“There are many things you can infer if you measure the distance of these shells,” Balbinot said. “You can reconstruct how these accretion events happened in detail, what was the orbit of the satellite [galaxy] that fell into the Milky Way and so on.”
Looking into the future
The past few billions of years have been quite peaceful for the Milky Way. The galaxy has been churning out stars and seeing them die at a steady rate while still absorbing the aftershocks of the earlier shake-ups.
But things will get rough again in the future. In fact, astronomers already observe the approach of the next galactic collision: the smash-up with two dwarf galaxies in the Milky Way’s orbit called the Large Magellanic Cloud and the Small Magellanic Cloud.
“The Magellanic Clouds entered into orbit around the Milky Way fairly recently, in the past few billion years,” Brown said. “We already see them having an influence on the Milky Way’s gravitational force field, and if we reconstruct the past really well, we might be able to run the whole thing forward and see when the clouds will merge with the Milky Way.”
Despite the Milky Way’s violent childhood, the most cataclysmic event still lies ahead: the collision with the Andromeda galaxy, the nearest large galactic neighbor.
Andromeda, currently over 2.5 million light-years from Earth, is among the celestial objects Gaia observes. The new data release will provide new insight into the encounter that will rattle the two galaxies some 4.5 billion years from now.
With Gaia, “you can actually measure quite well the motion of the Andromeda galaxy across the line of sight,” Brown said. “That gives you more constraints on the long-term future of the two galaxies.”
The sun will be near the end of its life when its mother galaxy encounters Andromeda, so humankind is unlikely to still be around to witness the galactic smash. Earth, for certain, will have long been uninhabitable, scorched by the increasingly hotter sun.
Related stories:
Still, untangling the galaxy’s past and future is a fascinating project, one that is set to continue for quite a few years as Gaia produces more and more data.
The telescope will retire in 2025, when it runs out of fuel. But it certainly is not past its peak, De Bruijne said. The consortium of 400 researchers that processes Gaia data is still refining the algorithms used to analyze the vast quantities of measurements that the telescope produces. These algorithms enable astronomers to find finer and finer details and new types of information in the vast data set. The June 13 release will, for example, contain the largest-ever catalog of chemical compositions of asteroids in the solar system and the largest-ever data set of binary star systems. Gaia’s next data release is already set to reveal thousands of new exoplanets, De Bruijne said.
More than 40 trillion gallons of rain drenched the Southeast United States in the last week from Hurricane Helene and a run-of-the-mill rainstorm that sloshed in ahead of it — an unheard of amount of water that has stunned experts.
That’s enough to fill the Dallas Cowboys’ stadium 51,000 times, or Lake Tahoe just once. If it was concentrated just on the state of North Carolina that much water would be 3.5 feet deep (more than 1 meter). It’s enough to fill more than 60 million Olympic-size swimming pools.
“That’s an astronomical amount of precipitation,” said Ed Clark, head of the National Oceanic and Atmospheric Administration’s National Water Center in Tuscaloosa, Alabama. “I have not seen something in my 25 years of working at the weather service that is this geographically large of an extent and the sheer volume of water that fell from the sky.”
The flood damage from the rain is apocalyptic, meteorologists said. More than 100 people are dead, according to officials.
Private meteorologist Ryan Maue, a former NOAA chief scientist, calculated the amount of rain, using precipitation measurements made in 2.5-mile-by-2.5 mile grids as measured by satellites and ground observations. He came up with 40 trillion gallons through Sunday for the eastern United States, with 20 trillion gallons of that hitting just Georgia, Tennessee, the Carolinas and Florida from Hurricane Helene.
Clark did the calculations independently and said the 40 trillion gallon figure (151 trillion liters) is about right and, if anything, conservative. Maue said maybe 1 to 2 trillion more gallons of rain had fallen, much if it in Virginia, since his calculations.
Clark, who spends much of his work on issues of shrinking western water supplies, said to put the amount of rain in perspective, it’s more than twice the combined amount of water stored by two key Colorado River basin reservoirs: Lake Powell and Lake Mead.
Several meteorologists said this was a combination of two, maybe three storm systems. Before Helene struck, rain had fallen heavily for days because a low pressure system had “cut off” from the jet stream — which moves weather systems along west to east — and stalled over the Southeast. That funneled plenty of warm water from the Gulf of Mexico. And a storm that fell just short of named status parked along North Carolina’s Atlantic coast, dumping as much as 20 inches of rain, said North Carolina state climatologist Kathie Dello.
Then add Helene, one of the largest storms in the last couple decades and one that held plenty of rain because it was young and moved fast before it hit the Appalachians, said University of Albany hurricane expert Kristen Corbosiero.
“It was not just a perfect storm, but it was a combination of multiple storms that that led to the enormous amount of rain,” Maue said. “That collected at high elevation, we’re talking 3,000 to 6000 feet. And when you drop trillions of gallons on a mountain, that has to go down.”
The fact that these storms hit the mountains made everything worse, and not just because of runoff. The interaction between the mountains and the storm systems wrings more moisture out of the air, Clark, Maue and Corbosiero said.
North Carolina weather officials said their top measurement total was 31.33 inches in the tiny town of Busick. Mount Mitchell also got more than 2 feet of rainfall.
Before 2017’s Hurricane Harvey, “I said to our colleagues, you know, I never thought in my career that we would measure rainfall in feet,” Clark said. “And after Harvey, Florence, the more isolated events in eastern Kentucky, portions of South Dakota. We’re seeing events year in and year out where we are measuring rainfall in feet.”
Storms are getting wetter as the climate change s, said Corbosiero and Dello. A basic law of physics says the air holds nearly 4% more moisture for every degree Fahrenheit warmer (7% for every degree Celsius) and the world has warmed more than 2 degrees (1.2 degrees Celsius) since pre-industrial times.
Corbosiero said meteorologists are vigorously debating how much of Helene is due to worsening climate change and how much is random.
For Dello, the “fingerprints of climate change” were clear.
“We’ve seen tropical storm impacts in western North Carolina. But these storms are wetter and these storms are warmer. And there would have been a time when a tropical storm would have been heading toward North Carolina and would have caused some rain and some damage, but not apocalyptic destruction. ”
Associated Press climate and environmental coverage receives support from several private foundations. See more about AP’s climate initiative here. The AP is solely responsible for all content.
It’s a dinosaur that roamed Alberta’s badlands more than 70 million years ago, sporting a big, bumpy, bony head the size of a baby elephant.
On Wednesday, paleontologists near Grande Prairie pulled its 272-kilogram skull from the ground.
They call it “Big Sam.”
The adult Pachyrhinosaurus is the second plant-eating dinosaur to be unearthed from a dense bonebed belonging to a herd that died together on the edge of a valley that now sits 450 kilometres northwest of Edmonton.
It didn’t die alone.
“We have hundreds of juvenile bones in the bonebed, so we know that there are many babies and some adults among all of the big adults,” Emily Bamforth, a paleontologist with the nearby Philip J. Currie Dinosaur Museum, said in an interview on the way to the dig site.
She described the horned Pachyrhinosaurus as “the smaller, older cousin of the triceratops.”
“This species of dinosaur is endemic to the Grand Prairie area, so it’s found here and nowhere else in the world. They are … kind of about the size of an Indian elephant and a rhino,” she added.
The head alone, she said, is about the size of a baby elephant.
The discovery was a long time coming.
The bonebed was first discovered by a high school teacher out for a walk about 50 years ago. It took the teacher a decade to get anyone from southern Alberta to come to take a look.
“At the time, sort of in the ’70s and ’80s, paleontology in northern Alberta was virtually unknown,” said Bamforth.
When paleontogists eventually got to the site, Bamforth said, they learned “it’s actually one of the densest dinosaur bonebeds in North America.”
“It contains about 100 to 300 bones per square metre,” she said.
Paleontologists have been at the site sporadically ever since, combing through bones belonging to turtles, dinosaurs and lizards. Sixteen years ago, they discovered a large skull of an approximately 30-year-old Pachyrhinosaurus, which is now at the museum.
About a year ago, they found the second adult: Big Sam.
Bamforth said both dinosaurs are believed to have been the elders in the herd.
“Their distinguishing feature is that, instead of having a horn on their nose like a triceratops, they had this big, bony bump called a boss. And they have big, bony bumps over their eyes as well,” she said.
“It makes them look a little strange. It’s the one dinosaur that if you find it, it’s the only possible thing it can be.”
The genders of the two adults are unknown.
Bamforth said the extraction was difficult because Big Sam was intertwined in a cluster of about 300 other bones.
The skull was found upside down, “as if the animal was lying on its back,” but was well preserved, she said.
She said the excavation process involved putting plaster on the skull and wooden planks around if for stability. From there, it was lifted out — very carefully — with a crane, and was to be shipped on a trolley to the museum for study.
“I have extracted skulls in the past. This is probably the biggest one I’ve ever done though,” said Bamforth.
“It’s pretty exciting.”
This report by The Canadian Press was first published Sept. 25, 2024.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
