So Mercury is special not just because it's the closest planet
to the Sun but also because the distance it is
from the Sun varies more than any other planet in our solar system.
Mercury actually has a very oval-shaped orbit compared to the rest.
Mercury is a natural laboratory for running experiments.
We can observe the planet's surroundings as it gets closer and farther away from the Sun
and see what changes.
When solar wind particles bounce off this magnetospheric boundary,
they generate low-frequency waves.
They're like ripples traveling upstream in the solar wind.
Farther from the Sun, the Sun's magnetic field is weaker.
We found that this is the key parameter that allows more waves to be generated.
This is something we could only have measured with Mercury,
thanks to how close it is to the Sun
and the shape of its orbit.