The sound waves were collected through ESA's Cluster mission which consists of four spacecraft that are designed to study the Earth's magnetic field and how it reacts and interacts with the particles coming from the Sun.
In order for a celestial body to be a planet, it should become gravitationally dominant with no other celestial body close to its size except for some of its satellites which, unfortunately, Pluto cannot.
The agency is launching its newest venture into space. This time, they are looking at a solar exploration where they are to send space rovers in many parts of the solar system to collect data. Particularly, they will be sending spacecraft to the moon, Saturn and the red planet.
A recent research on TRAPPIST-1 suggests it is almost 9.8 billion years old, twice the age of the solar system. It is basically a dwarf star residing 40 light-years away from the solar system.