From close encounters with Mars to vibrant meteor showers, the skies are certainly putting on a show this summer.
The Perseid meteor shower peaks this weekend. On the evening of Aug.12 to the morning of Aug.13, stargazers will see the best show the meteor shower has to offer.
"The reason we see the Perseids is because the earth travels through the tail of a comet," Kat Kelly, an astronomer at Vancouver's H.R. MacMillan Space Centre, told On the Coast guest host Angela Sterritt. "That's what we call the radiant, which is where the majority of meteors are coming from."
The best way to see the meteor shower is to find a constellation like Cassiopeia, and look just below it and to the left. Stargazers can see 60 to 70 meteors per hour, says Kelly.
"The Perseids are the biggest show of meteor showers that you can see in the Northern Hemisphere," says Kelly.
But that's not all that's going on in the sky.
Last week Mars was the closest it's been to Earth since 2003. It won't be closer until 2035. This month, the red planet will be visible at dawn. Those with amateur telescopes may be able to see some ice caps on the planet and definitely some colouration, according to Kelly.
Stargazers will also be able to spot Venus between sunset and midnight. Jupiter and Saturn will both be visible from 11 p.m. to the early hours of the morning, says Kelly.
"You can see all of them, in fact, without a telescope. They look like stars, but they don't twinkle. So that's the way you can tell," Kelly said.
To best enjoy the meteor shower and the multiple visible planets, Kelly urges people to reduce light pollution and relax.
"It's also nice to go to a park or a beach … somewhere that is secluded. Bring a blanket and sit back and enjoy."
Listen to the full story:
With files from On the Coast
Stalagmite study offers clues about Earth's past magnetic polarity shifts
A large team of researchers from China, Taiwan and Australia has found evidence of faster-than-expected shifts in Earth’s magnetic polarity several thousand years ago. In their paper published in Proceedings of the National Academy of Sciences, the group describes their study of stalagmites found in a cave in China and what they found.
Prior research has shown that the Earth’s magnetic field sometimes reverses polarity—such an event has been experienced only once by modern humans, but that was long before the age of satellites and electronics. In the modern age, such a reversal could spell trouble for many devices that we have come to rely on. For that reason, scientists study past reversals in the hope of predicting when the next might occur. In this new effort, the researchers traveled to the Sanxing Cave in Guizhou Province in southern China. There, they obtained samples of stalagmites (columns of calcium salts that rise from the floor of caves, caused by dripping water), which hold evidence of changes to the magnetic field going back thousands of years.
The Earth’s magnetic field is generated by liquid metal churning at depths 1,700 miles below the surface. But sometimes, that churning can change slightly, affecting the magnetic field. Prior research has suggested that a full reversal would likely take thousands of years, but this new research suggests it can happen in as few as 100.
The researchers report that the stalagmite sample taken from the cave showed evidence of magnetic field changes from 107,000 to 91,000 years ago—a span of 16,000 years. By studying the sample very precisely using a high-resolution cryogenic magnetometer, the researchers were able to trace changes in the magnetic field more precisely than has ever been done before. In so doing, they discovered that approximately 98,000 years ago, a magnetic reversal occurred over just a century and a half, approximately 10 times faster than had been believed possible. The researchers found several other phase changes, as well, with various degrees of fluctuation strength. They also found that when the magnetic field was weaker than normal, more fluctuations in strength occurred. They suggest such fluctuations likely caused some instability in convection in the planet’s outer core.
Earth’s magnetic field is not about to reverse, study finds
* Yu-Min Chou et al. Multidecadally resolved polarity oscillations during a geomagnetic excursion, Proceedings of the National Academy of Sciences (2018). DOI: 10.1073/pnas.1720404115
Polarity reversals of the geomagnetic field have occurred through billions of years of Earth history and were first revealed in the early 20th century. Almost a century later, details of transitional field behavior during geomagnetic reversals and excursions remain poorly known. Here, we present a multidecadally resolved geomagnetic excursion record from a radioisotopically dated Chinese stalagmite at 107–91 thousand years before present with age precision of several decades. The duration of geomagnetic directional oscillations ranged from several centuries at 106–103 thousand years before present to millennia at 98–92 thousand years before present, with one abrupt reversal transition occurring in one to two centuries when the field was weakest. These features indicate prolonged geodynamo instability. Repeated asymmetrical interhemispheric polarity drifts associated with weak dipole fields likely originated in Earth’s deep interior. If such rapid polarity changes occurred in future, they could severely affect satellites and human society.
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Earth's Magnetic Field Reversal Could Be More Rapid Than Thought, Study Reveals
An international team of researchers has found that Earth’s magnetic field, generated by material flowing in its core, can reverse more rapidly than previously thought, posing a major threat to ground and space-based infrastructure.
For years, scientists have known that the magnetic field of our planet plays a critical role in protecting our sophisticated satellites and communications systems from harmful solar wind and radiation. Occasional outbursts from the sun send streams of charged particles hurtling toward our world, but the magnetic field comes in between and deflects most of them.
However, the flow of liquid iron in Earth’s core — the material generating this field — can sometimes lead to its complete reversal or the situation where the magnetic north pole becomes south and vice versa.
While scientists have long known that such a change can leave Earth unprotected, the latest study conducted by researchers from Australian National University, National Taiwan University, and Southern University of Science and Technology in China is adding a further cause of worry.
The group analyzed an ancient rock called Stalagmite and found that Earth witnessed some rapid flips in the magnetic field in the past — fluctuations that were quicker than what has been estimated.
Till date, it was believed that polarity transitions occurred over thousands of years, with at least one complete reversal taking place some 773,000 years ago and several shorter flips — fluctuations to the point of complete transition — occurring in the ensuing years. These shorter events didn’t mark a permanent change in polarity but sent both ends drifting.
However, when the team conducted magnetic analysis and radiometric dating of the rock discovered in Southwest China, they were able to trace Earth’s geomagnetic history between 107,000 to 91,000 years ago. A close look at the 16,000-year-long data revealed that during the period, the polarity flipped just within a couple of centuries some 98,000 years ago.
This, as the researchers described, was nearly 30 times faster than a generally accepted time required for polarity flips and 10 times faster than the fastest rate of change. The team also noted that the strength of Earth’s magnetic field declined by about 90 percent when these changes occurred.
“The record provides important insights into ancient magnetic field behavior, which has turned out to vary much more rapidly than previously thought,” study co-author Andrew Roberts said in a statement.
Earth’s magnetic field strength has declined by about 10 percent over the last century and if such rapid flips are any indication, something similar could happen in the future, too. However, before drawing conclusions regarding the repetition of such rapid flips in the magnetic field, scientists have to conduct further studies to delve deeper into the processes behind polarity transition and how often they occur.
“Hopefully such an event is a long way in the future and we can develop future technologies to avoid huge damage, where possible, from such events,” Roberts concluded.
The study, titled “Multidecadally resolved polarity oscillations during a geomagnetic excursion,” was published August 20 in the journal PNAS.
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