By Lola Gayle, Editor-at-large
Auroras are definitely stunning when you look at them from below, but they’re even more spectacular when viewed from space. And they’re even more stunning when you find them throughout the Solar System and the Universe!
Auroras are a space weather phenomenon that occurs when electrically-charged electrons and protons collide with neutral atoms in the upper atmosphere. While they’re beautiful to look at, they also capture the imaginations of experts and citizen scientists who study the aurora and the complex processes that create them.
Luckily for the rest of us — especially those who live in areas that never see these phenomena — the internet is full of imagery and videos to help fill in the gap.
One such example is the ultra-high definition time-lapse video below which shows both the Aurora Borealis and Aurora Australis. This particular video was produced exclusively for NASA Television using time-lapse images shot from the International Space Station.
While mankind has witnessed auroras for thousands of years, we have only recently begun to understand what causes them.
Thanks to the lucky conjunction of two satellites in Oct. 2015, a ground-based array of all-sky cameras, and some spectacular Aurora Borealis, researchers announced they had uncovered evidence for an unexpected role that electrons have in creating the dancing auroras.
In that study, scientists compared ground-based videos of pulsating auroras — a certain type of aurora that appears as patches of brightness regularly flickering on and off — with satellite measurements of the numbers and energies of electrons raining down towards the surface from inside Earth’s magnetic bubble, the magnetosphere. The team found something unexpected: A drop in the number of low-energy electrons, long thought to have little or no effect, corresponds with especially fast changes in the shape and structure of pulsating auroras.
“Without the combination of ground and satellite measurements, we would not have been able to confirm that these events are connected,” said Marilia Samara, a space physicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author on the study.
See Also: Aurorasaurus project allows aurora-viewers around the world to compare sightings. [ Learn More ]
Earth isn’t the only celestial body that experiences auroras.
Auroras on Mars, for example, glow from green to blue in the Red Planet’s upper atmosphere depending on the activity of the Sun.
Immense solar storms have also been observed triggering X-ray auroras on Jupiter that are eight times brighter than normal and hundreds of times more energetic than Earth’s Northern lights.
The Sun is constantly ejecting streams of particles into space, which are carried by the solar wind. But sometimes a much larger eruption called a coronal mass ejection can increase the strength of the solar wind. This type of storm can wreak havoc here on Earth, but on Jupiter, the effect is even more intensified.
During these events, Jupiter’s magnetosphere is compressed, shifting its boundary with the solar wind inward by more than a million miles. That interaction at the boundary triggers the X-rays in Jupiter’s auroras, which cover an area bigger than the surface of the Earth.
More recently, NASA released a new composite image from Hubble Space Telescope and Voyager 2 showing auroras on the giant ice planet Uranus.
According to a NASA statement:
In 2011, the NASA/ESA Hubble Space Telescope became the first Earth-based telescope to snap an image of the auroras on Uranus. In 2012 and 2014 a team led by an astronomer from Paris Observatory took a second look at the auroras using the ultraviolet capabilities of the Space Telescope Imaging Spectrograph (STIS) installed on Hubble.
They tracked the interplanetary shocks caused by two powerful bursts of solar wind traveling from the sun to Uranus, then used Hubble to capture their effect on Uranus’ auroras — and found themselves observing the most intense auroras ever seen on the planet. By watching the auroras over time, they collected the first direct evidence that these powerful shimmering regions rotate with the planet. They also re-discovered Uranus’ long-lost magnetic poles, which were lost shortly after their discovery by Voyager 2 in 1986 due to uncertainties in measurements and the featureless planet surface.
Universal Light Show
But auroras within our own Solar System are nothing compared to the most powerful aurora ever discovered outside our solar system.
Not only is this aurora 10,000 times more powerful than any ever observed, it’s not coming from a planet at all. Instead, this behemoth is coming from a low-mass star at the boundary between stars and brown dwarfs.
According to astronomers, the new discovery reveals a “major difference between the magnetic activity of more-massive stars and that of brown dwarfs and planets.”