Comets from other star systems, such as 2019 Borisov, visit the sun’s neighborhood more frequently than scientists had thought, a new study suggests.
The study, based on data gathered as Borisovzipped by Earth at a distance of about 185 million miles (300 million kilometers) in late 2019, suggests that the comet repository in the far outer solar system known as the Oort Cloud might be full of objects that were born around other stars. In fact, the authors of the study suggest that the Oort Cloud might contain more interstellar material than domestic stuff.
Named after famous Dutch astronomer Jan Oort, who first proved its existence in the 1950s, the Oort Cloud is a spherical shell of small objects — asteroids, comets and fragments — far beyond the orbit of Neptune. The cloud’s inner edge is thought to begin about 2,000 astronomical units (AU) from the sun, and its outer edge lies about 200,000 AU away. (One AU is the average Earth-sun distance — about 93 million miles, or 150 million kilometers.)
No spacecraft has ever visited the Oort Cloud, and it will take 300 years for NASA’s farflung Voyager 1 probe to even glimpse the cloud’s closest portion.
Astronomers have very limited tools to study this intriguing world, as objects in the Oort Cloud don’t produce their own light. At the same time, these objects are too far away to reflect much of the sun’s light.
So how exactly did the scientists figure out that there must be so many interstellar objects in the Oort Cloud, and what did Borisov have to do with it?
Amir Siraj, a graduate student at Harvard University’s Department of Astronomy and lead author of the study, told Space.com in an email that he could calculate the probability of foreign comets visiting the solar system simply based on the fact that the Borisov comet had been discovered.
“Based on the distance that Borisov was detected at, we estimated the implied local abundance of interstellar comets, just like the abundance of ‘Oumuamua-like objects was calibrated by the detection of ‘Oumuamua,” Siraj said.
The mysterious ‘Oumuamua, first spotted by astronomers in Hawaii in October 2017, was the first interstellar body ever detected within our own solar system. The object passed Earth at a distance of 15 million miles (24 million km), about one-sixth of the distance between our planet and the sun. An intense debate about ‘Oumuamua’s nature ensued, as it wasn’t clear at first whether the object was a comet or an asteroid.
Even the detection of a single object can be used for statistical analysis, Siraj said. The so-called Poisson method, which the astronomers used, calculates the probability of an event happening in a fixed interval of time and space since the last event.
Taking into consideration the gravitational force of the sun, Siraj and co-author Avi Loeb, an astronomer at Harvard, were able to estimate the probability of an interstellar comet making its way to Earth’s vicinity. They found that the number of interstellar comets passing through the solar system increases with the distance from the sun.
“We concluded that, in the outer reaches of the solar system, and even considering the large uncertainties associated with the abundance of Borisov-like objects, transitory interstellar comets should outnumber Oort Cloud objects (comets from our own solar system),” Siraj added.
So why have astronomers seen just one interstellar comet so far? The answer is technology. Telescopes have only recently gotten powerful enough to be able to spot those small but extremely fast-travelling bodies, let alone study them in detail.
“Before the detection of the first interstellar comet, we had no idea how many interstellar objects there were in oursolar system,” said Siraj. “Theory on the formation of planetary systems suggests that there should be fewer visitors than permanent residents. Now we’re finding that there could be substantially more visitors.”
The astronomers hope that with the arrival of next-generation telescopes, such as the Vera C. Rubin Observatory, currently under construction in Chile, the study of extrasolar comets and asteroids will truly take off.
The new study was published in the journal Monthly Notices of the Royal Astronomical Society on Monday (Aug 24).
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NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
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.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
