Aurora The Northern & Southern Lights
Aurora The Northern & Southern Lights
Auroras are one of nature's most dazzling and mesmerizing phenomena. They are a natural light display that occurs in the polar regions, both in the northern hemisphere (Aurora Borealis or Northern Lights) and the southern hemisphere (Aurora Australis or Southern Lights). These breathtaking light shows are a result of interactions between the Earth's magnetic field and the solar wind.
# What causes aurora?
The sun is constantly emitting a stream of charged particles, known as the solar wind, which travels through space and towards Earth. When the charged particles come in contact with the Earth's magnetic field, they are deflected towards the poles. As the charged particles collide with the gases in the Earth's atmosphere, they release energy in the form of light, creating the stunning auroras.
The color of the auroras is determined by the type of gas particles in the Earth's atmosphere that the charged particles collide with. For example, oxygen molecules create green and red auroras, while nitrogen molecules create blue and purple auroras.
#Why the name of these lights are aurora?
The word "aurora" is derived from the name of the Roman goddess of the dawn, Aurora, who travelled from east to west announcing the coming of the sun .Ancient Greek poets used the corresponding name Eos metaphorically to refer to dawn, often mentioning its play of colors across the otherwise dark sky .
The words "borealis" and "australis" are derived from the names of the ancient gods of the north wind (Boreas) and the south wind (Auster) in Greek mythology.
#Colors and wavelengths of auroral light
Red :
At its highest altitudes, excited atomic oxygen emits at 630 nm (red); low concentration of atoms and lower sensitivity of eyes at this wavelength make this color visible only under more intense solar activity. The low number of oxygen atoms and their gradually diminishing concentration is responsible for the faint appearance of the top parts of the "curtains". Scarlet, crimson, and carmine are the most often-seen hues of red for the auroras.
Green :
At lower altitudes, the more frequent collisions suppress the 630 nm (red) mode: rather the 557.7 nm emission (green) dominates. A fairly high concentration of atomic oxygen and higher eye sensitivity in green make green auroras the most common. The excited molecular nitrogen (atomic nitrogen being rare due to the high stability of the N2 molecule) plays a role here, as it can transfer energy by collision to an oxygen atom, which then radiates it away at the green wavelength. (Red and green can also mix together to produce pink or yellow hues.) The rapid decrease of concentration of atomic oxygen below about 100 km is responsible for the abrupt-looking end of the lower edges of the curtains. Both the 557.7 and 630.0 nm wavelengths correspond to forbidden transitions of atomic oxygen, a slow mechanism responsible for the graduality (0.7 s and 107 s respectively) of flaring and fading.
Auroras can be seen throughout the year, but they are more visible during the winter months when the nights are longer and darker. The best time to see auroras is during periods of high solar activity, which occur every 11 years. These periods are known as solar maximums, and the next one is expected to occur in 2025-2026.
#Where Can You See Aurora?
Auroras can be seen from many places in the world, but the best places to view them are in the polar regions, close to the magnetic poles. In the northern hemisphere, the best places to view auroras are in Alaska, Canada, Scandinavia, and Iceland. In the southern hemisphere, the best places to view auroras are in Antarctica, New Zealand, and southern Argentina.
#Tips for Viewing Aurora
To increase your chances of seeing auroras, it is best to be away from light pollution and in a place with clear skies. It is also recommended to dress warmly and bring a lot camera to capture the magical display.
# Aurora in other planets
Both Jupiter and Saturn have magnetic fields that are stronger than Earth's,and both have extensive radiation belts. Auroras have been observed on both gas planets, most clearly using the Hubble Space Telescope, and the Cassini and Galileo spacecraft, as well as on Uranus and Neptune.
The aurorae on Saturn seem, like Earth's, to be powered by the solar wind. However, Jupiter's aurorae are more complex. Jupiter's main auroral oval is associated with the plasma produced by the volcanic moon Io, and the transport of this plasma within the planet's magnetosphere. An uncertain fraction of Jupiter's aurorae are powered by the solar wind. In addition, the moons, especially Io, are also powerful sources of aurora. These arise from electric currents along field lines ("field aligned currents"), generated by a dynamo mechanism due to the relative motion between the rotating planet and the moving moon. Io, which has active volcanism and an ionosphere, is a particularly strong source, and its currents also generate radio emissions, which have been studied since 1955. Using the Hubble Space Telescope, auroras over Io, Europa and Ganymede have all been observed.
Auroras have also been observed on Venus and Mars. Venus has no magnetic field and so Venusian auroras appear as bright and diffuse patches of varying shape and intensity, sometimes distributed over the full disc of the planet .An aurora was detected on Mars, on 14 August 2004, by the SPICAM instrument aboard Mars Express .By analyzing a map of crustal magnetic anomalies compiled with data from Mars Global Surveyor, scientists observed that the region of the emissions corresponded to an area where the strongest magnetic field is localized. This correlation indicated that the origin of the light emission was a flux of electrons moving along the crust magnetic lines and exciting the upper atmosphere of Mars.
In Conclusion
Auroras are a reminder of the beauty and wonder of nature. They are a result of the interaction between the Earth's magnetic field and the solar wind, creating a stunning display of light in the polar regions. With the next solar maximum expected in 2025-2026, it is the perfect time to plan a trip to view this natural wonder.
Auroras are one of nature's most dazzling and mesmerizing phenomena. They are a natural light display that occurs in the polar regions, both in the northern hemisphere (Aurora Borealis or Northern Lights) and the southern hemisphere (Aurora Australis or Southern Lights). These breathtaking light shows are a result of interactions between the Earth's magnetic field and the solar wind.
# What causes aurora?
The sun is constantly emitting a stream of charged particles, known as the solar wind, which travels through space and towards Earth. When the charged particles come in contact with the Earth's magnetic field, they are deflected towards the poles. As the charged particles collide with the gases in the Earth's atmosphere, they release energy in the form of light, creating the stunning auroras.
The color of the auroras is determined by the type of gas particles in the Earth's atmosphere that the charged particles collide with. For example, oxygen molecules create green and red auroras, while nitrogen molecules create blue and purple auroras.
#Why the name of these lights are aurora?
The word "aurora" is derived from the name of the Roman goddess of the dawn, Aurora, who travelled from east to west announcing the coming of the sun .Ancient Greek poets used the corresponding name Eos metaphorically to refer to dawn, often mentioning its play of colors across the otherwise dark sky .
The words "borealis" and "australis" are derived from the names of the ancient gods of the north wind (Boreas) and the south wind (Auster) in Greek mythology.
#Colors and wavelengths of auroral light
Red :
At its highest altitudes, excited atomic oxygen emits at 630 nm (red); low concentration of atoms and lower sensitivity of eyes at this wavelength make this color visible only under more intense solar activity. The low number of oxygen atoms and their gradually diminishing concentration is responsible for the faint appearance of the top parts of the "curtains". Scarlet, crimson, and carmine are the most often-seen hues of red for the auroras.
Green :
At lower altitudes, the more frequent collisions suppress the 630 nm (red) mode: rather the 557.7 nm emission (green) dominates. A fairly high concentration of atomic oxygen and higher eye sensitivity in green make green auroras the most common. The excited molecular nitrogen (atomic nitrogen being rare due to the high stability of the N2 molecule) plays a role here, as it can transfer energy by collision to an oxygen atom, which then radiates it away at the green wavelength. (Red and green can also mix together to produce pink or yellow hues.) The rapid decrease of concentration of atomic oxygen below about 100 km is responsible for the abrupt-looking end of the lower edges of the curtains. Both the 557.7 and 630.0 nm wavelengths correspond to forbidden transitions of atomic oxygen, a slow mechanism responsible for the graduality (0.7 s and 107 s respectively) of flaring and fading.
Blue: 
At yet lower altitudes, atomic oxygen is uncommon, and molecular nitrogen and ionized molecular nitrogen take over in producing visible light emission, radiating at a large number of wavelengths in both red and blue parts of the spectrum, with 428 nm (blue) being dominant. Blue and purple emissions, typically at the lower edges of the "curtains", show up at the highest levels of solar activity .The molecular nitrogen transitions are much faster than the atomic oxygen ones.
At yet lower altitudes, atomic oxygen is uncommon, and molecular nitrogen and ionized molecular nitrogen take over in producing visible light emission, radiating at a large number of wavelengths in both red and blue parts of the spectrum, with 428 nm (blue) being dominant. Blue and purple emissions, typically at the lower edges of the "curtains", show up at the highest levels of solar activity .The molecular nitrogen transitions are much faster than the atomic oxygen ones.
# When is the Best Time to See Aurora?
Auroras can be seen throughout the year, but they are more visible during the winter months when the nights are longer and darker. The best time to see auroras is during periods of high solar activity, which occur every 11 years. These periods are known as solar maximums, and the next one is expected to occur in 2025-2026.
#Where Can You See Aurora?
Auroras can be seen from many places in the world, but the best places to view them are in the polar regions, close to the magnetic poles. In the northern hemisphere, the best places to view auroras are in Alaska, Canada, Scandinavia, and Iceland. In the southern hemisphere, the best places to view auroras are in Antarctica, New Zealand, and southern Argentina.
#Tips for Viewing Aurora
To increase your chances of seeing auroras, it is best to be away from light pollution and in a place with clear skies. It is also recommended to dress warmly and bring a lot camera to capture the magical display.
# Aurora in other planets
Both Jupiter and Saturn have magnetic fields that are stronger than Earth's,and both have extensive radiation belts. Auroras have been observed on both gas planets, most clearly using the Hubble Space Telescope, and the Cassini and Galileo spacecraft, as well as on Uranus and Neptune.
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| Jupiter's Aurora |
The aurorae on Saturn seem, like Earth's, to be powered by the solar wind. However, Jupiter's aurorae are more complex. Jupiter's main auroral oval is associated with the plasma produced by the volcanic moon Io, and the transport of this plasma within the planet's magnetosphere. An uncertain fraction of Jupiter's aurorae are powered by the solar wind. In addition, the moons, especially Io, are also powerful sources of aurora. These arise from electric currents along field lines ("field aligned currents"), generated by a dynamo mechanism due to the relative motion between the rotating planet and the moving moon. Io, which has active volcanism and an ionosphere, is a particularly strong source, and its currents also generate radio emissions, which have been studied since 1955. Using the Hubble Space Telescope, auroras over Io, Europa and Ganymede have all been observed.
Auroras have also been observed on Venus and Mars. Venus has no magnetic field and so Venusian auroras appear as bright and diffuse patches of varying shape and intensity, sometimes distributed over the full disc of the planet .An aurora was detected on Mars, on 14 August 2004, by the SPICAM instrument aboard Mars Express .By analyzing a map of crustal magnetic anomalies compiled with data from Mars Global Surveyor, scientists observed that the region of the emissions corresponded to an area where the strongest magnetic field is localized. This correlation indicated that the origin of the light emission was a flux of electrons moving along the crust magnetic lines and exciting the upper atmosphere of Mars.
In Conclusion
Auroras are a reminder of the beauty and wonder of nature. They are a result of the interaction between the Earth's magnetic field and the solar wind, creating a stunning display of light in the polar regions. With the next solar maximum expected in 2025-2026, it is the perfect time to plan a trip to view this natural wonder.
By Saraf Aunjum Pravi (23101423)
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