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Learning from impacts areas on the Moon

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If you look at the Moon through binoculars or a small telescope, two sorts of terrain stand out.

There are lighter-coloured, mountainous regions that are heavily cratered. They are so heavily cratered that it is hard for an incoming object to make a new crater without hitting an existing one.

Surfaces like this are called “saturated”. The plains are called “maria” because early astronomers thought the Moon had seas. They have romantic names like Mare Tranquillitatis (Sea of Tranquillity), Mare Procellarum (Sea of Storms), Mare Nubium (Sea of Clouds) Mare Crisium (Sea of Crises) and so on. The maria are not water, but ancient lava flows.

At various points in its history the Moon has been hit by large objects, which blasted huge craters. Lava flowed up to fill the craters and then overflowed onto the surrounding land. We can see craters that are partially buried by this lava. The poetically named “Sinus Iridum” (Bay of Rainbows), is defined by a crescent of mountains that are the rim of a big crater that was buried by the lava forming the Mare Imbrium (Sea of Rains). However, one thing about these lava plains stands out, they are far less heavily cratered than the mountainous areas, suggesting that when the maria formed, the frequency of impacts had decreased a lot.

The Apollo astronauts brought back lots of rock samples from the Moon. Some of them were from the mountainous areas and some were from the lava plains. Using radioisotope dating it was possible to determine when the rocks solidified— in other words, when the rock formed.

As expected, the rocks from the maria were younger than the rocks from the mountainous areas, but not hugely younger. Like the Earth, the Moon formed about 4.5 billion years ago. The mountainous terrain dates back some four billion years. The impacts that formed the other maria are estimated to have taken place between three and 3.5 billion years ago.

The relatively light cratering of the maria indicates that by the time they formed, most of the bombardments that moulded the heavily cratered mountainous terrain happened within half a billion to a billion years after the Moon formed. The bombardment has not stopped and impacts are still happening, but at a far lower rate.

This fits our ideas as to how the Solar System was formed. A collapsing cloud of dust formed lumps. These lumps grew by colliding and sticking together. The biggest lump formed the Sun, and other lumps formed the planets.

As the newly born planets orbited the Sun, they swept up the material sharing their orbits. When the orbits had been “swept clean”, the impacts became much less frequent, but did not stop completely. Even today there are objects crossing the Earth and Moon’s path around the Sun, many of which pose a collision risk. These orbit-crossing bodies are a continuing threat, because objects in safe orbits continue to be moved into dangerous orbits by the gravitational attraction of the planet Jupiter.

So, by about 3.5 billion years ago, the big bombardment had ended. That was fortunate for us on Earth, because along with the other planets, we were being hit at least as often as the Moon was. The geological record here on Earth suggests that life appeared after the worst of the bombardment was over, and conditions were stable enough for living creatures to survive, proliferate and develop. We don’t know if there were any false starts.

In an age of huge telescopes, looking further out into the cosmos and back to the beginning of the universe, it is intriguing that important information on how our world began is written on the face of a familiar object that lights up our night skies.

•••

• After sunset, Jupiter lies in the south-east and Saturn in the south. Mars rises later.

• The Moon will reach its last quarter on Nov.16.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.

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The body of a Ugandan Olympic athlete who was set on fire by her partner is received by family

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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.

Kenya’s high rates of violence against women have prompted marches by ordinary citizens in towns and cities this year.

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.

The Canadian Press. All rights reserved.

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The ancient jar smashed by a 4-year-old is back on display at an Israeli museum after repair

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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.”

The Canadian Press. All rights reserved.

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B.C. sets up a panel on bear deaths, will review conservation officer training

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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.

The Canadian Press. All rights reserved.

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