Over the coming days, a wave of solar particle magnets will hit Earth, illuminating the sky. Tonight, tomorrow, and Friday, the northern lights may appear much farther south, possibly even close to you. There is an impending geomagnetic storm that may produce auroras over parts of Canada and the northern reaches of the continental United States. After sunset, the skies above Oregon, Iowa, Pennsylvania, and New York could all be seen to sparkle. It is the result of recent, unusually rare weather in space.
The History Of The Northern Light
The aurora borealis, also known as the northern lights, are stunning dancing waves of light that have mesmerised humanity for millennia. Despite its beauty, this amazing light show is actually rather a violent spectacle.
The magnetic field of our planet shields us from the onslaught of energetic solar particles, which may travel up to 45 million miles per hour (72 million kilometres per hour) in our upper atmosphere.
There are also southern lights, which you can read about below. As Earth’s magnetic field leads the particles toward the poles, the dramatic process develops into a cinematic atmospheric phenomena that astonishes and excites both scientists and skywatchers.
The term “aurora borealis” was first used in 1619 by Italian astronomer Galileo Galilei, who named it after the Roman goddess of dawn, Aurora, and the Greek god of the north wind, Boreas. However, the earliest known instance of the northern lights is thought to be a 30,000-year-old cave painting in France (opens in new tab).
Since then, cultures all across the world have marvelled at the celestial phenomena and given the dancing lights a variety of origin stories. The northern lights are said to be spirits having a game of ball with a walrus head in a North American Inuit legend(opens in new tab), while the Vikings believed the phenomena was light reflecting off the armour of the Valkyrie, the magical maidens who carried heroes into the afterlife.
What Are The Northern Lights?
The northern lights were also mentioned by ancient astronomers in their writings. For instance, a Chinese account from 193 B.C. mentions the aurora, and a royal astronomer under King Nebuchadnezzar II of Babylon engraved his report of the phenomena on a stone dating to 567 B.C., according to NASA (opens in new tab).
It wasn’t until the turn of the 20th century that the science underlying the northern lights was theorised. According to the theory put out by Norwegian physicist Kristian Birkeland, electrons that were released from sunspots and were directed toward the poles by the Earth’s magnetic field formed the atmospheric lights. The hypothesis would ultimately turn out to be accurate, but not until many years after Birkeland’s 1917 passing.
The solar wind is the result of the sun’s constant ejection of charged particles from its corona, or upper atmosphere. The aurora is created when that wind collides with Earth’s ionosphere, or high atmosphere. The phenomenon is known as the northern lights (aurora borealis) in the Northern Hemisphere and the southern lights in the Southern Hemisphere (aurora australis).
According to Billy Teets, director of Dyer Observatory at Vanderbilt University in Nashville, Tennessee, “these particles are redirected towards the poles of Earth by our planet’s magnetic field and interact with our atmosphere, depositing energy and causing the atmosphere to fluoresce.”
The chemical makeup of Earth’s atmosphere determines the vivid colours of the northern lights.
According to Teets, “Every sort of atom or molecule, whether it be atomic hydrogen or a molecule like carbon dioxide, absorbs and radiates its own unique combination of colours, which is akin to how each individual has a unique set of fingerprints. “Red, a hue created by the nitrogen molecules, and green, a hue produced by the oxygen molecules, are some of the dominant hues visible in aurorae.”
Solar wind is always present, although the sun goes through an approximately 11-year cycle of activity with its emissions. There are periods of calm between massive storms that blast Earth with enormous amounts of energy. The northern lights are most frequent and brightest during this time. According to the U.S. National Oceanic and Atmospheric Administration(opens in new tab), the most recent solar maximum, or time of peak activity, occurred in 2014. This puts the next one in roughly 2025.
Despite numerous developments in heliophysics and atmospheric science, there are still many unanswered questions regarding the northern lights. For instance, until a study published in the journal Nature Communications(opens in new tab) in June 2021, it was unclear how the energised particles in the solar wind are propelled to their extraordinary speeds (45 million mph). However, the study’s findings confirmed that the particles were propelled by a phenomenon known as Alfvén waves. Electromagnetic forces cause Alfvén waves, which are low-frequency but strong undulations in plasma. The electrons that produce the northern lights “surf” along these waves in Earth’s atmosphere, speeding quickly.
Northern Lights, Southern Lights And Steve
The southern lights are the northern lights’ Earthly twin in the Southern Hemisphere; they are identical in every way except for location. Scientists anticipate that they will happen simultaneously during a solar storm, but occasionally one will start before the other.
The comparison of the aurora borealis and aurora australis is one of the more difficult parts of nightside aurorae, according to Steven Petrinec, a physicist at Lockheed Martin who specialises in magnetospheric and heliospheric physics.
According to Petrinec, “While certain auroral emissions arise in opposing sectors in the two hemispheres at different times, for example, before midnight in the Northern Hemisphere and after midnight in the Southern Hemisphere, at the same magnetic local time in both hemispheres.
The aurora’s hemispheric asymmetry is partly caused by the sun’s magnetic field interfering with Earth’s magnetic field, although further study into the phenomena is still needed.
STEVE is an additional aurora-like event on Earth (“Strong Thermal Emission Velocity Enhancement”). STEVE is a shining atmospheric phenomena, like the northern and southern lights, but it differs slightly from them in appearance from their undulating auroral counterparts. The purple hue of these emissions is usual, and they frequently have a green picket-fence structure that slowly advances westward, according to Petrinec.
In addition, STEVE is more apparent than auroras at latitudes nearer the equator.
STEVE is the consequence of two mechanisms, according to a 2019 study that was published in the journal Geophysical Research Letters(opens in new tab): The picket-fence structure originates from electrons falling into the atmosphere, whereas the mauve streaks are brought on by the heating of charged particles in the upper atmosphere. As the aurora is driven by the same process, STEVE is a unique type of aurora hybrid.
Where And When To See The Northern Lights
Both astronomy enthusiasts and vacationers share the dream of witnessing the northern lights. Thankfully, they happen regularly.
Owner of the northern lights tour firm Lights Over Lapland and photographer Chad Blakely remarked, “The northern lights are happening 24 hours a day, seven days a week, 365 days a year” (opens in new tab). But it doesn’t imply it’s simple to find them; you have to be there at the appropriate time.
According to the Troms Geophysical Observatory(opens in new tab), any location within the “auroral zone,” which is located within an approximate 1,550-mile (2,500-kilometer) radius of the North Pole, is the greatest location to view the northern lights. The aurora is most usually seen there, while it can occasionally be seen farther south during extremely powerful solar storms.
For instance, a strong solar outburst in March 1989 allowed individuals as far south as Honduras to briefly see the northern lights. However, there were also some drawbacks: the geomagnetic storm that boosted the aurora also momentarily cut out electricity over the whole Canadian province of Quebec.
To optimise visibility when in the auroral zone, it is essential to stay as far away from city lights as you can. It’s best to base yourself in a place with good infrastructure, such as Fairbanks, Alaska; Yellowknife, Canada; Svalbard, Norway; Abisko National Park, in Sweden; Rovaniemi, Finland; or pretty much anywhere in Iceland, as it can be quite difficult to enter the middle of the Arctic wilderness, even with a guide.
When the sky becomes sufficiently dark to see the aurora, between September and April is the greatest time of year to see the northern lights. (Locations in the far north enjoy the midnight sun, or summer days with 24 hours of daylight.) According to the Geophysical Institute of the University of Alaska Fairbanks, the biggest activity often occurs between 9 p.m. and 3 a.m. (opens in new tab). Remember the moon’s phases, as a bright full moon could illuminate the night sky. Because you won’t be able to see the aurora through the clouds, you should also check your local weather prediction.
NASA is also looking for hints as to how the northern lights function. The Parker Solar Probe, which is presently orbiting the sun and will eventually come near enough to “touch” the corona, was launched by the space agency in 2018. The spacecraft will gather data there that could provide additional insight into the northern lights.
From August 17 to August 19, a geomagnetic storm watch was issued by NOAA’s Space Weather Prediction Center (yeah, that’s a thing), with the potential to become a G3 storm “owing to coronal high speed stream (CH HSS) and coronal mass ejection (CME) influences.”
Now let’s examine that, shall we?
It all started a few days ago on the sun, 93 million miles away. A huge outburst of magnetised plasma from the sun’s corona, which is its outermost layer, is known as a coronal mass ejection (CME). Two of these CMEs have recently been seen erupting on the sun and moving toward Earth, according to scientists. They should show up on August 18.
The two bursts could merge en way to form a geomagnetic storm that reaches G3, or “strong” levels. This suggests that it could produce auroras closer to the equator than usual as well as near the poles.
When very energetic solar particles strike the atmosphere of the Earth, auroras are created. Similar to how neon lights work, these particles stimulate the gases in the sky and cause them to shine. One of the few ways to observe space weather from the ground is through auroras, which are often restricted to the poles but can occur considerably farther away if the sun is excited enough.
However, a coronal hole high-speed stream is anticipated to arrive tonight and trigger a G1, or “small,” geomagnetic storm before the CMEs arrive tomorrow. A coronal hole is a colder region in the sun’s corona that can produce solar winds travelling at great speeds and carrying charged particles across the solar system. High-speed streams from coronal holes can potentially cause auroras on Earth.
On August 19, forecasters anticipate G2 or “moderate” storm activity to continue.
The NOAA issues a warning that geomagnetic storms may cause disruptions if they intensify. According to a NOAA press release, geomagnetic storms “may impair near-Earth orbit and surface infrastructure, potentially disrupting communications, the electric power grid, navigation, radio, and satellite operations.”
It is not anticipated that the impending storms would disrupt technology much. Nevertheless, this could be a nice time to put away all of your technology for a while and gaze up at the stars. The sky might just start to glow.
