The Northern Lights, also known as the Aurora Borealis, are a spectacular natural light display that occurs in the night sky in the northern hemisphere. These dancing lights can glow many different colors and take on various shapes and patterns. The phenomenon results from collisions between gaseous particles in the Earth's atmosphere and charged particles released from the Sun. When these particles collide, energy is released in the form of visible light. The Northern Lights fascinate people around the world, who travel far just for a glimpse. This article will examine what causes this dazzling display, where and when it occurs, its colors and structures, viewing tips, and some of the most remarkable Northern Lights displays on record. By the end, you'll understand the science behind this celestial phenomenon and how best to witness its ethereal beauty.
Where Northern Lights Occur
The northern lights, also known as the aurora borealis, occur primarily in high latitudes in the northern hemisphere. They are visible in the Arctic region, which includes northern countries like Canada, Alaska, Norway, Iceland, Sweden, Finland, and Greenland.
The southern hemisphere also experiences a southern counterpart called the aurora australis, also known as the southern lights. These occur near the South Pole and are visible from high latitudes in Antarctica and southern countries like New Zealand, Australia, and southern parts of Chile and Argentina.
To see the magnificent lights of the aurora, you generally need to be located between 60 and 75 degrees north or south latitudes. In the northern hemisphere, this is a band that stretches across Alaska, Canada, Iceland, Greenland, Norway, Sweden, Finland and Russia. The further north you are, the more opportunities there are to potentially observe the northern lights.
Some major cities where the northern lights can sometimes be seen include Whitehorse in Canada's Yukon territory, Tromsø in northern Norway, Reykjavik in Iceland, and Fairbanks in Alaska. However, to get the best views, it's ideal to venture outside of city lights into darker rural areas.
So in summary, the auroras occur in polar regions and are best viewed from northern latitude countries in proximity to the Arctic Circle or southern latitude countries near Antarctica. This allows skywatchers to witness the most brilliant and powerful light displays when conditions align.
Causes of the Northern Lights
The Northern Lights are caused by the interaction between the solar wind and Earth's magnetic field. The solar wind is a stream of charged particles, mostly electrons and proton, that are constantly ejected from the Sun's upper atmosphere, known as the corona. These particles travel at speeds of up to 2 million mph.
When the solar wind reaches Earth, it deforms the shape of Earth's protective magnetic field around the planet. The magnetic field acts as a shield, protecting us from most of the particles. However, some particles do filter down into the upper atmosphere near the North and South poles.
Here, the solar wind particles collide with atoms of gas, such as oxygen and nitrogen. This collision of solar wind and atmospheric gases excites the atoms, causing them to light up. The aurora occurs when the atoms return to their normal state and release photons of light. Different gases produce different colors - oxygen is green and red, nitrogen blue and purple.
The intensity of the lights depends on the speed and density of the solar wind. When the Sun's activity increases, it produces larger numbers of particles in the solar wind. This leads to more intense auroral displays. The position of the lights is also affected by the flows and currents in the near-Earth magnetic environment. So the dancing lights of the aurora provide a beautiful insight into the electrically charged particles from the Sun interacting with the protect magnetic bubble that surrounds our planet.
Solar Activity and the Solar Wind
The Northern Lights are ultimately powered by the Sun. Our star is much more than a glowing ball of gas - it has a complex magnetic field that extends far out into space, well beyond the planets.
The Sun's magnetic field goes through cycles of activity, including sunspots, solar flares, and huge eruptions called coronal mass ejections. This activity sends a stream of charged particles, mostly electrons and protons, out into space at speeds of over 1 million mph. This is known as the solar wind.
The solar wind carries the Sun's complex and ever-changing magnetic field along with it. When the solar wind reaches Earth, about 93 million miles away, it begins to interact with our planet's own magnetic field, setting the stage for the dazzling light display we know as the Northern Lights. So even though the lights appear high in our atmosphere, their ultimate origin lies at the Sun.
Interaction with Earth’s Magnetic Field
The Northern Lights are caused by particles from the sun called the solar wind. These particles are deflected by Earth's magnetic field towards the north and south poles.
Earth's magnetic field extends far out into space and forms a protective barrier called the magnetosphere. When the solar wind interacts with the magnetosphere, the particles are funneled down into the upper atmosphere near the magnetic poles.
The magnetosphere acts like a shield, deflecting most of the solar wind particles around Earth. However, some particles do become trapped by Earth's magnetic field lines. As the particles approach the poles, they spiral along the magnetic field lines and collide with atoms and molecules in the upper atmosphere. This collision causes the atoms to light up, creating the beautiful colors of the aurora.
So in summary, the Earth's magnetosphere plays a key role by shielding the planet from most of the solar wind and channeling the particles into a collision course with our atmosphere, setting the stage for the dazzling night time light show we know as the Northern Lights.
Ionization of Atmospheric Gases
The colors of the northern lights come from collisions between the charged particles of the solar wind and the gases in Earth's upper atmosphere. When the charged particles collide with atoms and molecules like oxygen and nitrogen, the atoms become "excited" or energized.
The excitation causes the atmospheric gases to glow, emitting the visible light we see as the northern lights. The incoming electrons essentially knock the electrons in the atmospheric gases into higher energy states. When the energized atmospheric electrons return to their normal low energy states, they release photons of light. This process is called ionization.
The specific colors of light emitted depend on which atmospheric gas is ionized. Oxygen emits green and red light, while ionized nitrogen glows blue and purple. The combination of these colored lights from the different gases mixed through the atmosphere is what creates the haunting multi-colored glow of the northern lights. The colors can even shift and change as the balance of energized gases changes.
So in summary, it is the ionization and excitation of Earth's atmospheric gases like oxygen and nitrogen by charged solar particles that causes the glowing, dancing lights of the northern lights across the sky. The ionization process produces the signature colors that make the aurora borealis such a stunning natural phenomenon to witness.
Colors and Shapes
The colors of the northern lights come from collisions between the charged particles of the solar wind and different gases in the upper atmosphere. The most common auroral color is green, which comes from oxygen atoms high up in the thermosphere. Blue and purplish-red aurorascome from higher altitudes where there is less oxygen. Molecular nitrogen causes the ripples and curtains of purple aurora. Ionized nitrogen creates red auroras.
The shape of the aurora depends on the geomagnetic activity that guides the solar particles. During quiet geomagnetic conditions, the aurora form diffuse glows. With increased activity, the aurora form curtains, arcs, or bands that flow across the sky. The shapes seem to shimmer and move quickly during active geomagnetic storms. Some displays feature tall rays that seem to reach up from the horizon. Occasionally, twisting spirals can form during periods of exceptionally high solar wind. The ever-changing auroral displays continue to fascinate skywatchers.
Ideal Conditions for Viewing the Northern Lights
The Northern Lights are a beautiful but temperamental natural phenomenon. Many factors impact whether they will be visible during any given night. The most important requirements are high solar activity, clear and dark skies, high latitude locations, and the right time of year.
Solar activity, which refers to disturbances on the Sun such as solar flares and coronal mass ejections, is the main driver of the Northern Lights. These energetic events send charged particles streaming toward Earth that then interact with our atmosphere to create the light show. The more active the Sun is, the brighter and more widespread the Aurora tend to be. Solar activity rises and falls in approximately 11 year cycles.
Equally important as solar activity is having clear, dark skies to see the lights. Any kind of light pollution from cities, streetlights, or the moon can make the Northern Lights harder to observe. Seeking out rural areas and times with minimal moonlight is best. Some of the world's best Aurora viewing is found near the Arctic Circle partly because of the long winter nights.
Latitude is also key. The closer you are to the Arctic Circle, the more easily the Northern Lights can be seen. Fairbanks, Alaska and Yellowknife, Canada are popular aurora destinations. In the Northern Hemisphere, the lights are visible in an oval centered over the magnetic north pole. The southernmost areas where they may be glimpsed are places like Scotland and the upper U.S. Midwest.
Finally, the time of year matters. In the far north, the Aurora is only visible in winter when skies are dark and solar activity is increasing after its minimum point. The weeks around the September and March equinoxes are known for heightened Northern Lights activity. Determined viewers may catch the Aurora on dark clear nights throughout the winter anywhere within the auroral oval. With the right conditions, witnessing the breathtaking dance of the Northern Lights is possible.
Some of the most incredible and memorable northern lights displays in recent history include:
The Carrington Event - In 1859, the largest recorded geomagnetic storm occurred during solar cycle 10. It was named after Richard Carrington, who observed a huge solar flare preceding the geomagnetic storm. The auroras were seen around the world, even in tropical areas. People in the northeastern US could read newspaper print from the aurora light. Telegraph systems across Europe and North America failed from the storm.
Halloween Storms - In October and November 2003, a series of powerful solar storms caused vibrant red, blue, and green auroras visible across North America, Europe, and Asia. These were the most significant auroral events in over 40 years, since the magnetic storm of November 1960. They occurred during solar cycle 23.
St. Patrick's Day Storm - In March 2015, a severe geomagnetic storm caused by a coronal mass ejection produced intense northern lights displays seen across large areas of North America, Europe, and Russia. The auroras were photographed in areas as far south as Mexico and central US states like Missouri and Arkansas. The solar storm peaked on St. Patrick's Day, March 17, hence the name.
Great Auroral Storm of August and September 1859 - This was another significant display that occurred shortly after the Carrington event during solar cycle 10. Vivid red, green, and purple auroras were seen around the world. In the US, the lights were so bright even from the midwest that people thought buildings were on fire. The storm occurred over several days in late August and early September 1859.
These major geomagnetic storms producing incredible auroral displays give us a glimpse of the power and beauty of the northern lights. They serve as reminders to keep looking up at the night sky for the next dazzling aurora.
Viewing the Northern Lights
The best places to see the northern lights are in areas closest to the north geomagnetic pole, including Alaska, Canada, Iceland, Greenland, Norway, Sweden, and Finland. For optimal viewing, head away from light pollution in cities to dark rural areas with open vistas facing north.
The aurora borealis is only visible on nights with sufficient solar activity and clear dark skies. Check aurora forecasts and apps like AuroraNotify before heading out. Ideal viewing is between 10pm-2am.
To photograph the northern lights, use a DSLR camera with manual settings, a wide angle lens, and a sturdy tripod. Set your ISO between 800-3200 and use exposures between 5-30 seconds. Compose with an interesting foreground like mountains or trees to add scale. Experiment with different exposures and manual focus.
Some key tips: get away from light pollution, find unobstructed northern horizons, check aurora forecasts, dress warmly, and don't give up if the lights are faint at first. With luck and persistence, you'll be rewarded with a dazzling display of the northern lights sweeping across the night sky.