Phaeton

Phaeton is a hypothetic planet that was located between Mars and Jupiter.  Description

Phaeton is the name of a hypothetical planet raised once have existed between the orbits of Mars and Jupiter whose destruction is leading to the formation of the asteroid belt. Most of the phaeton surface was likely covered by snow and ice and temperatures were easily in the negative. Where there was no snow, active volcanoes and lava flows represent extreme temperatures differently. When Phaeton suddenly and unexpectedly explodes, like a nova in our solar system. It expands and brightens to a daylight brightness and then fades. In a few months, the leading edge of the blast reaches Earth. The day and night sky is set ablaze with great showers of brilliant meteors. Such a spectacle would undoubtedly leave a most ominous and profound impression on the inhabitants of that time(like the dinosaurs). Just how the planet itself was demolished remains a mystery although it seems probable that Jupiter or its Galilean moons were responsible. It's also possible that the planet was destroy by a hypothetical rogue (9th) planet known as Tyche or could have overtook mars, and when phaeton reached the the roche limit it broke apart.