Three-body problem: The smallest planet ever discovered has been found in a unique system.

Astronomers have found evidence that an object approximately twice the size of the Moon may be a planet. If confirmed, this planet would be the smallest discovered beyond the Solar System. It orbits a pulsar and two white dwarfs, which are themselves extreme and unusual dead stars, suggesting that the planet has somehow managed to survive under such conditions. The study has been published in the journal Astronomy and Astrophysics, according to IFLScience.

Pulsars and white dwarfs are referred to as dead stars because they form after the death of ordinary stars. Pulsars are a type of neutron star that arises from a supernova explosion, while white dwarfs are remnants of stars like the Sun.

In this system, which consists of three dead stars, the pulsar PSR J0337+1715 plays a central role, as it orbits with a white dwarf around another white dwarf. Thus, we are dealing with a unique version of the three-body problem.

Scientists had suspected that a very small planet, roughly twice the mass and size of the Moon, was orbiting these three dead stars. This was indicated by the pulsar's unusual behavior, particularly the periodicity of its radio emissions. Now, astronomers claim to have evidence that a planet may indeed exist there.

The pulsar orbits a common center of mass with the white dwarf on a 1.6-day orbit, while both dead stars orbit around another white dwarf on a 327-day orbit.

Observations have shown that a small object, which could be a planet, is orbiting these three stars on a 3000-day orbit. Therefore, if you were on the surface of this world, you would see three stars in the sky.

If this is indeed a planet, it would be the smallest known beyond the Solar System. However, such a planet would have a tough time surviving the supernova explosion that formed the pulsar. This planet would likely have been ejected from the system.

If it did survive, it would be a remarkable feat of endurance. The planet would have had to withstand not only the supernova explosion but also the transformation of two Sun-like stars into massive red giants, after which they became white dwarfs. On the other hand, this planet could have formed from the debris of other planets that failed to survive in this system.

If new observations confirm the existence of the smallest known planet beyond the Solar System, another issue arises. This potential planet is slightly larger than Pluto, which is classified as a dwarf planet. This means that scientists may need to reconsider the criteria for defining planets.