A meteorite that crashed into Australia back in 1969 contains stardust dating back some 7 billion years, predating the formation of Earth by 2.5 billion years. The remarkable discovery offers a snapshot of the conditions that existed long before our solar system came into existence.
Ancient grains found inside the Murchison meteorite have been dated to between 5 billion and 7 billion years old, according to new research published in Proceedings of the National Academy of Sciences. The new paper was led by astronomer Philipp Heck from the University of Chicago.
These grains originated as interstellar dust, and they’re now considered to be the oldest known solid materials on Earth, which formed around 4.5 billion years ago. It’s a remarkable finding, as these materials are evidence of the conditions that existed prior to the formation of our solar system. And indeed, these grains are already providing new astronomical information, including evidence of a “baby boom” period of star formation that happened several billion years ago.
“This is one of the most exciting studies I’ve worked on,” said Heck in a press release.
Stardust comes from stars (shocking, I know) and is hurled into space by stellar winds. Eventually, these bits of stellar matter re-accumulate, forming yet more stars, and sometimes planets, moons, and meteorites (fun fact: you’re also made from this stuff). On Earth, traces of these grains are scant, appearing in only 5 percent of meteorites. They’re also very tiny. As a University of Chicago press release notes, “a hundred of the biggest ones would fit on the period at the end of this sentence.” More specifically, they’re about 8 microns across, which is roughly the size of a single red blood cell.
David Bekaert, a researcher at the Center for Petrographic and Geochemical Research (CPRG) in Nancy, France, who wasn’t involved with the new study, said interstellar dust particles that predate our Sun are known as “presolar grains,” a portion of which reached rocky bodies that arose during the formation of our solar system.
“We’ve known their existence in primitive meteorites for a long time,” Bekaert told Gizmodo. “However, assessing how old they are, and whether or not they were generated in a single star formation episode that predated the formation of our own solar system, had remained hampered by the lack of reliable techniques to date individual presolar grains.”
Key to the new study was an abundance of presolar grains packed inside the Murchison meteorite and a new strategy to date them. But the first step was to isolate the grains.
“It starts with crushing fragments of the meteorite down into a powder,” Jennika Greer, a co-author of the study and a graduate student at the Field Museum and the University of Chicago, said in the press release. “Once all the pieces are segregated, it’s a kind of paste, and it has a pungent characteristic—it smells like rotten peanut butter.”
This putrid-smelling stuff was then dissolved with acid, leaving a few dozen of these presolar grains behind. To date these isolated grains, the researchers applied a technique that measured the degree to which the grains were bombarded by cosmic rays—high-energy particles that zip through space and can penetrate solid objects. Because prolonged exposure to cosmic rays results in heavier elements, the researchers took note of the quantity of these easily detectable elements found in the grains to infer their relative age.
Results showed that the presolar grains were quite ancient, having absorbed a tremendous amount of cosmic rays over the eons. The oldest grains were dated to about 7 billion years ago, with the majority dating to between 4.6 billion and 4.9 billion years ago and a small handful dating to 5.6 billion years ago. So all the interstellar particles found in the Murchison meteorite originated before the formation of our solar system and Sun.
Interestingly, this result shows that star formation was not constant in the galaxy. The glut of particles dating to 4.6 million-4.9 billion years ago suggests these grains originated during a time of intense stellar formation—a kind of baby boom for stars in the Milky Way (our galaxy formed around 8 billion years ago). And in fact, Heck said it was “one of the key findings of our study.”
Bekaert agreed, saying the new paper “relates an impressive technical achievement, as well as an important scientific discovery, providing us with new insights into the evolution of matter within our galactic neighborhood,” up to around 7 billion years ago, he told Gizmodo.
With this new technique, astronomers would be wise to re-visit similar meteorites containing presolar grains to corroborate these findings. There’s still plenty of history to be found in these primordial objects.
The most massive explosion since the Big Bang was just spotted in deep space – BGR
As far as astronomers know, the Big Bang is why we’re all here. The massive explosion sent all the matter we see in the universe flying, expanding rapidly and coalescing into the stars, planets, and other objects that fill the cosmos. Now, astronomers have detected what they believe is the largest explosion ever observed by humans, and it took place in a cluster of galaxies nearly 400 million light-years away.
The record-breaking explosion is believed to have originated in a black hole at the heart of the Ophiuchus galaxy cluster. It was spotted using data from NASA’s Chandra X-ray Observatory as well as the ESA’s XMM-Newton and other instruments in Australia and India.
When you think of a black hole you probably think of a point in space that gobbles up everything in its path. That’s not too far from the truth, but black holes can have more explosive personalities, too. Black holes are known to blast material into space as well, forming strong jets of matter and energy moving at incredible speeds. The initial observations of this colossal explosion were made years ago, but have only now been confirmed.
Chandra observations reported in 2016 first revealed hints of the giant explosion in the Ophiuchus galaxy cluster. Norbert Werner and colleagues reported the discovery of an unusual curved edge in the Chandra image of the cluster. They considered whether this represented part of the wall of a cavity in the hot gas created by jets from the supermassive black hole. However, they discounted this possibility, in part because a huge amount of energy would have been required for the black hole to create a cavity this large.
Further research showed that there actually was an explosion, and the big boom is now considered to be the largest ever documented by science. According to NASA, the amount of energy involved in this recent blast is around five times greater than the previous largest space explosion on record.
At a distance of 390 million light-years from Earth, the explosion actually took place, well, around 390 million years ago. It’s impossible for us to know what the galaxy cluster looks like today, but astronomers are using their ability to look back in time to see the record-breaking explosion today, and that’s pretty awesome.
Why Mars Needs Leap Days, Too – The New York Times
This Saturday, you have the gift of time. Feb. 29 is a leap day — a calendar oddity that gives us an extra day.
You probably know why: The time it takes Earth to rotate on its axis is called a day — but it doesn’t take an even number of days to complete a single loop around the sun, or one orbit. Instead it takes a messy 365.2422 spins. And yet the calendar year runs out after 365 days. That means that when the clock strikes midnight on New Year’s Eve, Earth hasn’t quite circled all the way back to its starting point.
“It’s like being a quarter of a day behind at the end of every workday,” said Richard Binzel, a planetary scientist at the Massachusetts Institute of Technology. “After four days, you would need one full day to catch up on all your work. It’s the same for the Earth’s orbit and the calendar.”
So every four years, the month of February has 29 days instead of 28. But even that solution isn’t perfect, because the year is not exactly 365.25 days. We have to make additional tweaks. If a year is divisible by 100, for example, there’s no extra day — unless the year is divisible by 400. In other words, the year 2000 was a leap year, but 1900 was not, nor will the year 2100 be one (its nearest leap years will be 2096 and 2104).
These contortions are awkward, but they’re fairly straightforward compared with the adjustments that would need to be made to the calendars of alien civilizations if they existed elsewhere in our solar system.
On Mars, a year lasts 668.6 Martian days. Should the calendar year include only 668 days, it would quickly fall out of alignment with the Martian seasons. Luckily, astronomers, science-fiction writers and enthusiastic hobbyists have presented several proposals for Martian calendars.
“I daresay there have been more different proposals for Mars calendars than there are different calendars for the Earth,” said Michael Allison, a retired NASA scientist.
One of the most popular — the Darian calendar — was created in 1985 by Thomas Gangale, a space law expert. It breaks up the lengthy year into 24 months of 27 and 28 Martian days — each of which alternates between Latin and Sanskrit names for constellations of the zodiac, like Virgo and its Sanskrit equivalent, Kanya.
To keep the calendar in harmony with the Martian seasons, Dr. Gangale proposed that even-numbered years have 668 Martian days (except those divisible by 10), and odd-numbered years have 669 Martian days. That works out to an average of 668.6 — the length of a Martian year.
But it isn’t the only way to reach that average. Dr. Allison has proposed another calendar — “a whimsical exercise,” he said.
He thought it was important to maintain similarities to Earth’s calendar, just in case future Martians wanted to celebrate major holidays. So he retained the 12 months we know and love, then added 10 extra months (each is 30 or 31 days) and named them after Johannes Kepler, Ray Bradbury and other famous astronomers, mathematicians and science-fiction writers.
In his calendar, Dr. Allison proposed that years divisible by five would have three leap days, for a total of 671 days. But all other years would have 668 days.
While there have been many imaginative calendars suggested for Mars, none is in common use.
“We count Martian days and Martian years,” said John Callas, the project manager of NASA’s Mars Exploration Rover project, which directs the Curiosity rover. “But we don’t care right now that seasonal events may be drifting relative to calendar events.”
So scientists and engineers who work on surface missions on the red planet use two systems. One counts the number of Martian days that have elapsed since the start of a particular mission and the other marks the location of Mars within its orbit (and thus allows NASA to note the season). The two systems allow scientists to sidestep the complications that arise in trying to sync the two.
“There may come a time — if you have cultural civilizations that are living in this environment and you want to preserve the seasonal significance of a particular date on the calendar — that you would likely introduce some sort of a leap system,” Dr. Callas said.
With so many proposals, we’re certainly prepared.
Calendars for other worlds in our solar system get exceedingly difficult to calculate.
“On Jupiter, it would be hopeless,” Dr. Binzel said. “It’s a gas planet and different latitudes have different rotation periods. I think the Jovians would find themselves very confused.”
Then there’s Venus where a single rotation of the planet takes longer than its entire year (it also spins upside down). No matter how you work the problem, that’s never going to come out nice and even.
Luckily, Venus doesn’t have noticeable seasons, so you need not worry if your calendar doesn’t sync up with the year.
But there is one planet where the calendar would need zero finessing: Mercury. The small planet revolves exactly three times, or days, over the course of two years — allowing its calendar to naturally align every other year.
In that way, it may be like many other planets orbiting stars throughout our galaxy. Astronomers suspect that plenty of closer exoplanets revolve exactly once every year. These planets show only one face to their star, leaving the other side in perpetual darkness. And while that might make life on those worlds difficult, their calendars would always be in sync.
But even if by some wild cosmic coincidence, a planet’s orbit could be evenly divided into days, it likely wouldn’t stay that way for long.
Earth’s spin, for example, is slowing over time. Eventually one year won’t last 365.2422 days but precisely 365 days, allowing us to drop the leap year — at least temporarily.
“You have to enjoy the leap year while it’s here,” said Konstantin Batygin, a professor of planetary science at the California Institute of Technology. “Because in millions of years, maybe tens of millions of years, it’s just not going to be around anymore.”
Sync your calendar with the solar system
Never miss an eclipse, a meteor shower, a rocket launch or any other astronomical and space event that’s out of this world.
Astronomers spot the largest explosion since the Big Bang – ZME Science
Ever want to make a literal dent in space? Apparently a supermassive black hole in the Ophiuchus galaxy cluster did when it erupted and caused the largest known explosion since the Big Bang. The black hole punched a dent the size of 15 Milky Ways in the surrounding space.
Galaxy clusters like Ophiuchus are some of the largest objects in the universe and contain thousands of individual galaxies, dark matter, and hot gas. At the heart of the Ophiuchus cluster is a giant galaxy that contains a black hole with a mass equivalent to around 10 million suns.
Professor Melanie Johnston-Hollitt, from the Curtin University node of the International Centre for Radio Astronomy Research, said the event was extraordinarily energetic. “We’ve seen outbursts in the centres of galaxies before but this one is really, really massive,” she said. “And we don’t know why it’s so big.”
The explosion — captured using four telescopes; NASA’s Chandra X-ray Observatory, ESA’s XMM-Newton, the Murchison Widefield Array (MWA) in Western Australia and the Giant Metrewave Radio Telescope (GMRT) in India — occurred 390 million light-years from Earth. It was so powerful that it punched a cavity in the cluster plasma, the super-hot gas surrounding the black hole. The find was made with Phase 1 of the MWA, when the telescope had 2048 antennas pointed towards the sky.
Scientists dismiss the idea that it could be caused by an energetic outburst, as it was too large. The explosion was initially recorded by the Chandra Observatory in 2016, however, the results were dismissed as astronomers believed a cavity of that magnitude was impossible.
Lead author of the study Dr. Simona Giacintucci, from the Naval Research Laboratory in the United States, said the blast was similar to the 1980 eruption of Mount St. Helens, which ripped the top off the mountain. “The difference is that you could fit 15 Milky Way galaxies in a row into the crater this eruption punched into the cluster’s hot gas,” she said.
Professor Johnston-Hollitt, who is the director of the MWA and an expert in galaxy clusters, says that this finding underscores the importance of studying the universe at different wavelengths. She also likened the finding to discovering the first dinosaur bones.
“It’s a bit like archaeology,” she says. “We’ve been given the tools to dig deeper with low frequency radio telescopes so we should be able to find more outbursts like this now….We’re soon going to be gathering (MWA) observations with 4096 antennas, which should be ten times more sensitive. I think that’s pretty exciting.”
The study was published in The Astrophysical Journal.
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