Tag Archives: magnetic field

Maybe the Earth’s magnetic field is not weakening

The uncertainty of science: New data using date-stamped jars covering the period from the 8th to the 2nd century BC suggest that the 8th century BC was a period when the Earth’s magnetic field was particularly strong, leading the scientists doing the research to conclude that the Earth’s magnetic field might not be weakening and that the recent field strength decline detected in the past two hundred years might simply be part of the field’s normal fluctuations.

This new data is certainly worthwhile, but the press release surely doesn’t reveal how the scientists were able to extrapolate future magnetic field strength from 8th century BC fluctuations. At a minimum, I would need to see a graph showing the measured field strength from the 8th century BC to the present time to see how today’s field strength compares with the past. Unfortunately, the press release does not provide this.

Planes flying at high latitudes can travel through clouds of high cosmic radiation

The uncertainty of science: Researchers have found evidence that suggests that planes flying at higher latitudes can sometimes fly through concentrated pockets of high cosmic radiation.

“We have flown radiation sensors onboard 264 research flights at altitudes as high as 17.3 km (56,700 ft) from 2013 to 2017,” says Kent Tobiska, lead author of the paper and PI of the NASA-supported program Automated Radiation Measurements for Aerospace Safety (ARMAS). “On at least six occasions, our sensors have recorded surges in ionizing radiation that we interpret as analogous to localized clouds.”

…Conventional wisdom says that dose rates should vary smoothly with latitude and longitude and the height of the aircraft. Any changes as a plane navigates airspace should be gradual. Tobiska and colleagues have found something quite different, however: Sometimes dose rates skyrocket for no apparent reason. “We were quite surprised to see this,” says Tobiska.

All of the surges they observed occurred at relatively high latitudes, well above 50 degrees in both hemispheres. One example offered in their paper is typical: On Oct 3, 2015, an NSF/NCAR research aircraft took off from southern Chile and flew south to measure the thickness of the Antarctic ice shelf. Onboard, the ARMAS flight module recorded a 2x increase in ionizing radiation for about 30 minutes while the plane flew 11 km (36,000 feet) over the Antarctic Peninsula. No solar storm was in progress. The plane did not abruptly change direction or altitude. Nevertheless, the ambient radiation environment changed sharply. Similar episodes have occurred off the coast of Washington state.

The theories proposed to explain this at the link are not very convincing, and suggest to me that they really do not know what causes this. All we do know is that it likely associated with the interaction of the Earth’s magnetic field and cosmic radiation.

The recent changes in Earth’s magnetic field

New data from Europe’s Swarm constellation of satellites detail the recent bigger-than-expected changes that have been occurring in the Earth’s magnetic field.

Data from Swarm, combined with observations from the CHAMP and Ørsted satellites, show clearly that the field has weakened by about 3.5% at high latitudes over North America, while it has strengthened about 2% over Asia. The region where the field is at its weakest – the South Atlantic Anomaly – has moved steadily westward and weakened further by about 2%. These changes have occured over the relatively brief period between 1999 and mid-2016.

It was already known that the field has weakened globally by about 10% since the 19th century. These changes appear to be part of that generally weakening. Some scientists have proposed that this is the beginning of an overall flip of the magnetic field’s polarity, something that happens on average about every 300,000 years and last occurred 780,000 years ago. At the moment, however, we have no idea if this theory is correct.

Earth’s magnetic field might not be flipping

The uncertainty of science: A new analysis of the past strength of the Earth’s magnetic field suggests that today’s field is abnormally strong and that, even with the 10% decline in the field’s strength in the past two centuries, it remains stronger than the average over the past 5 million years.

The new data also suggests that the field might not be about to shut down and then reverse polarity, as some scientists have theorized based on the 10% decline. Instead, the data says that the field’s unusual strength today only means that the decline is bringing it back to its average strength, and is not necessarily an indication of a pending reversal.

To put it mildly, there are a lot of uncertainties here, including questions about the database that has been used previously by geologists to estimate the past strength of the Earth’s magnetic field. The database might have been right, but the new study raises significant new questions.

Magnetic field science satellites launched

An Atlas 5 rocket successfully launched four NASA research satellites Thursday night designed to study the behavior of the Earth and Sun’s magnetic fields at high resolution.

The quartet of observatories is being placed into an oblong orbit stretching tens of thousands of miles into the magnetosphere — nearly halfway to the moon at one point. They will fly in pyramid formation, between 6 miles and 250 miles apart, to provide 3-D views of magnetic reconnection on the smallest of scales.

Magnetic reconnection is what happens when magnetic fields like those around Earth and the sun come together, break apart, then come together again, releasing vast energy. This repeated process drives the aurora, as well as solar storms that can disrupt communications and power on Earth. Data from this two-year mission should help scientists better understand so-called space weather.

The big solar hotshots of 2013.

The big solar hotshots of 2013.

The article is a nice and visually fascinating overview of the twelve most impressive solar events during the past year. Interestingly, I think #7 is the most significant in that it involved things that didn’t happen.

As small sunspot group NOAA 1838 was falling apart, another active region NOAA 1839 appeared just in time to avoid a spotless day, which would have been the first since 14 August 2011! A spotless day during a solar cycle maximum is not uncommon, but it remains of course a rare event. This absolute low in sunspot number highlighted a period of very low solar activity, with hardly any flares (no C-flares from 7 till 17 September: 11 consecutive days) and no (minor) geomagnetic storms for a full month! Meanwhile, the magnetic field near the solar north pole (finally) completed its reversal, whereas this magnetic flip is still ongoing at the south pole. These reversals testify we’re close to the maximum of solar cycle 24. [emphasis mine]

The phrases in bold clarify where we presently stand with the solar cycle. The southern magnetic field is in the process of reversing, but has not yet completed the flip.

Scientists studying a meteorite thought to come from the asteroid Vesta have concluded that it contains evidence that the asteroid once had a magnetic field.

Scientists studying a meteorite thought to come from the asteroid Vesta have concluded that it contains evidence that the asteroid once had a magnetic field.

This appears to be a very tentative finding, intriguing and possible, but not yet strongly proven.

Astronomers have measured the most powerful magnetic field ever found around a star.

Astronomers have measured the most powerful magnetic field ever found around a star.

The star’s magnetic field is 20,000 times stronger than the Sun’s, and almost 10 times stronger than that detected around any other high-mass star. At about 35 times the Sun’s mass, the O-type star NGC 1624-2 lies in the open star cluster NGC 1624, about 20,000 light-years away in the constellation Perseus.

When a solar storm slammed into both the Earth and Mars in January 2008, scientists were able to directly measure the importance of the Earth’s magnetic field in protecting our atmosphere from oxygen loss.

When a solar storm slammed into both the Earth and Mars in January 2008, scientists were able to directly measure the importance of the Earth’s magnetic field in protecting our atmosphere from oxygen loss.

They found that while the pressure of the solar wind increased at each planet by similar amounts, the increase in the rate of loss of martian oxygen was ten times that of Earth’s increase. Such a difference would have a dramatic impact over billions of years, leading to large losses of the martian atmosphere, perhaps explaining or at least contributing to its current tenuous state. The result proves the efficacy of Earth’s magnetic field in deflecting the solar wind and protecting our atmosphere.

An experiment designed to mimic the dynamo at the Earth’s core is about to be turned on.

Mad scientists at their best! An experiment designed to mimic the dynamo at the Earth’s core is about to be turned on.

Ten years in the making, the US$2-million project is nearly ready for its inaugural run. Early next year, the sphere will begin whirling around while loaded with 13,000 kilograms of molten sodium heated to around 105 °C. Researchers hope that the churning, electrically conducting fluid will generate a self-sustaining electromagnetic field that can be poked, prodded and coaxed for clues about Earth’s dynamo, which is generated by the movement of liquid iron in the outer core. If it works, it will be the first time that an experiment that mirrors the configuration of Earth’s interior has managed to recreate such a phenomenon.

This is a really very cool experiment, as we really do not have a good understanding of how planetary magnetic fields are produced.

A summary of Messenger’s first six months in orbit around Mercury

A summary of Messenger’s first six months in orbit around Mercury.

Though packed with lots of results, this strikes me as the most interesting discovery so far:

Orbital data reveal that Mercury’s magnetic field is offset far to the north of the planet’s center, by nearly 20% of Mercury’s radius. Relative to the planet’s size, this offset is much more than in any other planet, and accounting for it will pose a challenge to theoretical explanations of the field. . . . This finding has several implications for other aspects of Mercury, says Anderson, who co-authored several of the presentations in the MESSENGER session. “This means that the magnetic field in the southern hemisphere should be a lot weaker than it is in the north. At the north geographic pole, the magnetic field should be about 3.5 times stronger than it is at the south geographic pole.