Aurora Borealis

Aurora Borealis is one of the fascinating visual spectacles one can experience on our planet. They are waves of colours dancing amidst surreal arctic landscapes.

The aurora borealis is also known as the northern lights—a vibrant exhibition of the Earth’s magnetic field mingling with charged particles from the Sun.

What is Aurora Borealis?

Aurora borealis is a natural light extravaganza in the Earth’s atmosphere, mostly occurring in high-altitude regions in the Arctic. In the Antarctic area, it is called aurora australis. Auroras create surreal and dynamic patterns of dazzling lights that appear as spirals, curtains, flickers, or rays that consume the whole sky.

The term “aurora” is coined from the name of the Roman goddess of Dawn, Aurora. In ancient times, Greek poets used this term metaphorically to mention dawn or patterns of colour across the dark sky. “Borealis” was derived from the Greek god name “Boreas”.

Creation of Aurora

Every second, highly energetic particles from the Sun crash into the Earth’s upper atmosphere. The Earth’s magnetic field regulates these powerful rays of particles. Particles are redirected towards the poles (arctic and antarctic). The dynamic process transforms into a vibrant display of colours and light.

The Sun emits charged particles from its upper or corona region at every moment. It creates a phenomenon called solar wind. When such charged particles enter the upper atmosphere or ionosphere, auroras emerge. In the northern pole, it is called aurora borealis (northern lights), while in the southern pole, it is called aurora australis (southern lights).

Each type of molecule, compound, or atom has its own apparent spectrum of colours. For example, carbon dioxide radiates and absorbs its own distinctive class of colours. Those are as unique as the distinctive nature of each human DNA. Most of the time, red (nitrogen molecule) and green (oxygen molecule) are seen as the predominant colours during aurora borealis.

Video about Aurora Borealis

Aurora Borealis Observation History

In 1619, Astronomer Galileo Galilei coined the term “aurora borealis”. However, the earliest known record of aurora borealis is on a cave painting in France (thirty thousand years old).

The oldest genuine auroral citing was written in a Chinese record called “Fu-Pao”. There is a very detailed description of the nature and movement of aurora lights. The author used phrases like ‘strong lightning travelling around the star Su’. In 1570 A.D., a simple drawing of the aurora illustrated burning candles hovering above the clouds.

• During the 1790s, Henry Cavendish made significant observations of the aurora phenomenon. He applied triangulation to calculate that the aurora light produced around 100-130 km in height.
• In 1902, Physicist Kristian Birkeland deduced that the auroral light was produced by currents propagating through the gases of the higher atmosphere. This principle was later used to create present-day neon lights.
• After the invention of cameras, we are able to capture images of aurora lights. It is one of the most sought after natural phenomena on the planet.

Important Aurora Borealis Regions

Aurora borealis is frequently visible in Northern Scandinavia in a band that stretches between 66°N and 69°N, which we call the Aurora Zone. The band can expand when geomagnetic activity is high.

The aurora borealis is visible from being close to the centre of the Arctic Circle, such as Alaska, Canada, Iceland, Greenland, Norway, Sweden, Finland and Russia. A geomagnetic storm can cause the auroral ovals (north and south) to expand, bringing the aurora to lower latitudes.

Here are some of the most iconic places to explore aurora borealis,

• Svalbard, Norway
• Kakslauttanen, Finland
• Jukkasjärvi, Sweden
• Reykjavik, Iceland
• St. Petersburg, Russia
• Northern Canada
• Scotland, United Kingdom

Aurora on Other Planets

We know that auroral lights are created when magnetic fields interact with highly charged particles. Like the Earth, every other planet in the solar system has a magnetic field. So there is always the possibility of aurora lights in planets with strong magnetic fields.

• Jupiter and Saturn have massive magnetic fields that are much stronger than the Earth’s.
• They both have wide radiation belts that allow them to ionise huge quantities of solar winds. As they are predominantly rotating gas balls, the frequency of aurora lights is far greater than one can imagine from the Earth.
• The Hubble Space Telescope, the Cassini and Galileo satellites have observed such optical phenomena on Jupiter, Saturn, Uranus and Neptune.
• Like the Earth’s aurora activities, Saturn also seems to produce such lights by ionising solar winds. On the other hand, there are other complex activities that produce auroral lights. One of the important auroral ovals of Jupiter is directly connected with plasma generated by Moon Lo Volcano. This massive amount of plasma travels into the magnetosphere, causing gigantic auroral lights.
• Venus and Mars have also witnessed below average aurora lights.
• The magnetic field on Venus is almost zero. Therefore, the produced spectrum colours are not as vibrant as a perfect aurora light. Normally they are bright and diffused. In some conditions, it might spread across the whole horizon of the planet. Here, aurora occurs when solar wind electrons interact with the nightside atmosphere.
• On August 14, 2014, the SPICAM instrument (Mars Express) discovered an aurora on Mars. It was found at Terra Cimmeria.
• In July 2015, the first-ever interstellar aurora was detected. It was hovering around the brown dwarf planet LSR J1835+3259. The red aurora was a million times brighter than aurora borealis on the Earth. As per the current understanding, it was a byproduct of charged particles mingling with hydrogen gas in the atmosphere.