Remember a few months back when more of us than usual were treated to a spectacular display of aurorae?
If you’re one of the people who missed out, you could soon be in with another chance of seeing the show, thanks to a phenomenon known as the Russell-McPherron effect.
For a long time, the reason for this pattern eluded scientists.
Then, in 1973, two geophysicists called Christopher Russell and Robert McPherron presented a theory involving the magnetic fields of the Earth and the Sun.
Most of the time, the Earth and Sun’s magnetic fields are misaligned, leaving our planet’s field less open to the aurora-causing effects of the solar wind.
However, towards the equinox, the two fields line up but point in opposite directions, which allows for greater capture of the charged particles that cause aurora.
“During the equinoxes, the orientation of the Earth’s poles is (almost) perpendicular to that of the sun,” Dr Ciaran Beggan, a geophysicist at the British Geological Survey, explained to Newsweek.
Advertisement “This maximizes the ‘coupling’ between the solar wind and the Earth’s magnetic field.
That’s why, back in May, Earth had its strongest geomagnetic storm in 20 years, with aurorae seen far further south than usual.
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A few months ago, a spectacular display of aurorae was witnessed by a larger number of people than usual. If you were among those who were not able to witness the show, there may soon be another opportunity to do so since the Russell-McPherron effect works.
While the official duration of aurora season is thought to be from late August to mid-April, there are two specific times during that season—September and March, or the times surrounding the fall and spring equinoxes—when auroral activity is typically highest.
The cause of this pattern escaped scientists for a very long time. Subsequently, in 1973, a theory concerning the Earth and Sun’s magnetic fields was proposed by geophysicists Christopher Russell and Robert McPherron.
The Earth’s magnetic field is less susceptible to the solar wind’s aurora-causing effects because the Earth and Sun’s magnetic fields are typically not aligned. The two fields, however, align but point in different directions toward the equinox, allowing for a greater capture of the charged particles responsible for aurora.
Nevertheless, it should be highlighted that there are other theories explaining the increase in geomagnetic activity, albeit they may not be as well-accepted as those put forth by Russell and McPherron.
Dr. Ciaran Beggan, a geophysicist with the British Geological Survey, told Newsweek that “the orientation of the Earth’s poles is (almost) perpendicular to that of the sun” during the equinoxes.
By doing this, the ‘coupling’ between the Earth’s magnetic field and the solar wind is maximized. Because one of the Earth’s poles points away from the solar wind during the summer or winter, there is less coupling between the two and, on average, fewer storms. “.
Anyway, given that we are currently in the midst of the Sun’s 11-year cycle of minimum to maximum activity and back again, this phenomenon might very well be made worse this year.
The solar maximum that we are currently experiencing has the potential to bring massive clouds of charged particles hurtling toward Earth, as well as a sharp rise in sunspots, solar flares, and coronal mass ejections. Because of this, Earth experienced its strongest geomagnetic storm in 20 years in May, when aurorae were visible much further south than usual.
It is possible that we will witness an even more spectacular display than previously if we see another incredible sunspot around the time of the equinoxes.
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