Last weekend, the aurora australis and aurora borealis were all across social media with the beautiful colours in the sky.
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When the sun erupts, almost like doing a burp, it releases particles and gas that are highly charged, which slam into Earth's magnetic field. This protective bubble of ours then funnels the stuff from the sun into the poles.
Since these particles are charged, it excites the gas in our atmosphere, and when it does, causes it to glow, producing the aurora - similar to a neon sign.
However, any object that has an atmosphere and some sort of magnetic field can get aurora - and this is something that we have seen on other planets in our solar system.
Every planet in our solar system has had detectable auroras. The moon does not - but that is due to its lack of atmosphere. Pluto is so far away it would be hard to detect.
While Mars has a much weaker magnetic field than Earth, something we think contributed to Mars turning from a water planet like Earth to the drier, harsher place it is today, is its aurora. Mars has a few different types of aurora - most likely due to the different magnetic field or bubble it has, as well as the different atmosphere. One of the aurorae appears more snake-like rather than the wavy pattern we get on Earth.
Jupiter by far has probably the best aurora in the solar system. The energy in the aurora on Jupiter is many times stronger than that on Earth. They also produce X-rays at the poles when they occur.
Despite being very far away from the sun, the aurora on Jupiter are often caused by Jupiter's own magnetic field. It is over 20 times stronger than Earth's and creates a few interesting effects. One of them is due one of its moons, Io.
Io and Jupiter have a unique interaction. The massive gravitational pull of Jupiter causes volcanic eruptions on Io. In turn, it appears Io produces an electrical current that hits Jupiter, igniting the gases in Jupiter and producing the aurora. These aurora are often blue and purple.
Every element has its own colours signature - something that we use to identify what is present on other planets, stars, and galaxies. On Earth, the aurora are related to the oxygen and nitrogen - oxygen giving the pink and green colours in an aurora, and nitrogen the blue and purples - which is the same on Jupiter.
On other planets, the aurora are often in other colours - ones we cannot see with our eyes.
Aurora on Uranus were spotted nearly 40 years ago, occurring in ultraviolet light. They have also been viewed in the infrared - the same with Neptune which has also had infrared aurora spotted. However, these planets are so far away from the sun, the aurora are weak and infrequent.
The aurora are not as unique as it may seem, but tell us a lot of valuable information about the planets in our solar system and their interaction with the sun.
And they are always breathtaking to see and look at.
- Brad Tucker is an astrophysicist and cosmologist at Mt Stromlo Observatory and the National Centre for the Public Awareness of Science at the ANU.
