We often take the most important things for granted. For example, when was the last time you thought about Earth’s magnetic field, if ever? Besides pointing compass needles northward or directing migrating birds, does Earth’s magnetic field have any other effect on our daily lives?
Spoiler alert: every second, Earth’s magnetic field deflects about 1.5 million tons of material ejected from the Sun at high speed. If it were not there, the atmosphere would suffer direct and continuous erosion. It would not be able to avoid the direct impact of those solar particles, which would sweep everything that protects us away with them. Therefore, without Earth’s magnetic field, life as we know it would not exist on the surface of our planet. Of course, our technological societies would not be possible either, since the magnetic field also protects our electronic equipment, not just our DNA, from this same bombardment.
Earth (like Mercury, Jupiter, Saturn, Neptune, and Uranus) is surrounded by a relatively intense magnetic field that originates, for the most part, within the planet. It is believed that, at the current stage of Earth’s evolution, it is powered by the cooling and crystallization of the core. This agitates the liquid iron that surrounds it, creating powerful electrical currents that generate the magnetic field that extends into space. This type of magnetic field is known as a geodynamo, and the force field structure that deflects most of the solar wind and forms a protective shield is called the magnetosphere.
To understand how it works in more detail, let’s now travel about 80 kilometers (50 miles) above our heads. At that altitude, something fundamental happens. And a significant fraction of the gas in this region is ionized. In other words, the gas particles have an electric charge, generally because they have lost an electron in their structure due to the energetic radiation coming from our star. Charged particles behave in a very special way. They follow the magnetic field lines and, therefore, they move as if they were in lanes on a highway.
Before we continue, it is important to point out that the Sun, like all stars, ejects large amounts of material in the form of charged particles at very high speed. It does this in addition to electromagnetic energy across the entire range — our eyes are only sensitive to visible light, which is a very narrow range. This is what is known as stellar wind; or solar wind, in the case of our star. The connection between the magnetosphere and the solar wind is the heart of what is known as space weather.
If we could visualize Earth’s magnetic field, we would see that it is what we scientists call a dipolar magnetic field. This is where the lines of force leave one hemisphere and enter the other. In normal convention, the outgoing field lines are magnetic north and the incoming field lines are magnetic south. In the case of the Earth, sometimes to avoid confusion with geographic north, the convention is reversed and the magnetic north pole points south and the magnetic south pole points north. In the north, the field lines point inward, which is the opposite of what happens in magnets. The field is also inclined 11.5 degrees with respect to the planet’s axis of rotation, which is what defines the geographical north and south poles.
A fascinating structure
The Earth’s magnetic field is twice as intense at the poles as at the equator. We know this thanks to instruments on satellites that have explored both the intensity and direction of Earth’s magnetic field and confirmed its dipole-shaped nature. In addition to being complex, the form it takes is variable. Some of its components are the Van Allen radiation belts, the ring current, the magnetic tail, and the magnetopause.
Among just a few fascinating details of the structure of the magnetic field that surrounds our planet is a region that is made up of cold, dense plasma that rotates with the Earth. The Van Allen belts are also out there, where particles move with relativistic energies, in other words, close to the speed of light.
In what is known as the ring current, energetic ions move at much slower speed than in the Van Allen belts, but they have a higher density and produce an electric current that surrounds the Earth. Electrons move from the twilight zone to the zone where it is night and positively charged ions move in the opposite direction. This ring current generates a magnetic field that points in the opposite direction of the Earth’s magnetic field and that, when it becomes intense, decreases the intensity of the field measured on the surface. There are more currents that connect the ring current to the ionosphere and play an essential role in the northern lights and space weather.
To understand the global configuration of the way particles move in our space environment, we need one more fundamental ingredient. The solar wind is also magnetic. A way to simply visualize this interaction is to imagine the solar wind as the current of a river and the Earth and its magnetic field as a giant stone. Since the solar wind is supersonic we have a bow shock and behind the obstacle we have the tail. In this case, it is a magnetic tail. As for magnetic storms and where they come from, we will leave those for another occasion.
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.
