Astronomers Discover Surprising Similarity Between Earth and Mercury

The northern lights are not unique to Earth.

Well, their specific configuration is, but the aurora is not. Auroras have been observed on Saturn, Jupiter, Mars, Venus and even some exoplanets. Now, researchers have shown that these aerial wave forms are present on Mercury and may be generated by a universal mechanism throughout the solar system.

On Earth, the northern and southern lights are caused by solar storms on the surface of the sun. This activity releases huge clouds of electrically charged particles out into space, stretching over millions of miles.

Some of these charged particles eventually collide with our planet, and while most of them are deflected, some end up being captured by the Earth's magnetic field. At this point, they travel down toward the North and South poles where they collide with atoms and molecules in the atmosphere.

These collisions transfer energy to the electrons inside the atoms in our atmosphere, causing them to become excited. When these electrons eventually calm down again, they release this energy in the form of visible light. The colors of this light will vary depending on the different elements present in the atmosphere.

Now, researchers have shown that a similar situation happens on Mercury, the least explored rocky planet in our inner solar system. Their results were published Tuesday in the journal Nature.

"Even in the smaller magnetosphere of Mercury compared to Earth, electrons are accelerated and transported in a mechanism highly similar to that on Earth and are capable of precipitating to the planet's surface and generating X-ray auroras," Sae Aizawa told Newsweek. She is a researcher at the Research Institute in Astrophysics and Planetology, which is in Toulouse, France, and the Nature paper's first author.

An X-ray aurora releases energy in the X-ray region of the electromagnetic spectrum, as opposed to the visible light we see in the northern lights.

The team was able to draw these conclusions by studying data from the BepiColombo probe's Mercury flyby in 2021.

It is not clear whether distance from the sun affects the intensity of these auroras. But it does seem clear that the same underlying mechanisms are used to produce auroras on these wildly different planets.

"While magnetized planets in the solar system differ in terms of their intrinsic magnetic field strength, presence of an atmosphere and presence of radiation belts, accelerated electrons have now been observed to be transported to the vicinity of the planet and precipitate in all cases except for Neptune," Aizawa said.

This indicates that the processes are "a universal mechanism for aurora generation," she said.