This page is about Planet V. You may be looking for Krypton (hypothetical planet), or Phaeton (hypothetical planet).
Planet V is a hypothetical fifth terrestrial planet posited by NASA scientists John Chambers and Jack J. Lissauer to have once existed between Mars and the Asteroid Belt. In their hypothesis the Late Heavy Bombardment of the Hadean era began after perturbations from the other terrestrial planets caused Planet V's orbit to cross into the asteroid belt.[1] Chambers and Lissauer presented the results of initial tests of this hypothesis during the 33rd Lunar and Planetary Science Conference, held from March 11 through 15, 2002.
The Hypothesis[]
According to the hypothesis, there were five terrestrial planets that formed during the planetary formation era. These being Mercury, Venus, Earth, Mars, and finally Planet V. Planet V supposedly began on a low-eccentric and circular orbit between Mars and the Asteroid belt, and it was around 1.9 AU's away from the Sun. While this orbit was long lived, the orbit was unstable at a time scale of 600 million years. Eventually, perturbations from the inner planets drove Planet V onto a high eccentric orbit that crossed into the inner asteroid belt. This caused many asteroids to scatter into Mars-crossing and resonant orbits by their close encounters with Planet V. Many of these said asteroids eventually drove into Earth-crossing orbits, temporally enhancing the lunar impact rate. This process continued until Planet V was ultimately lost, most likely by colliding with the Sun after entering the V6 secular resonance.[2]
In 2007, an article published on Icarus had reported over about 96 simulations examining the Solar System's orbital dynamics with five rocky planets, and in the majority of them, Planet V was either ejected or impacted the Sun without the other rocky planets suffering collisions. The results of these were more frequent if Planet V's mass was less than 0.25 Mars masses. The other simulations that were tested weren't considered successful, as Planet V either survived in the 1 billion year length of them, or the collisions occurring between the planets.[3]
Alternate Model[]
It is proposed that a direct impact from Planet V onto Mars may had formed the Borealis Basin on the red planet as an explanation for the Late Heavy Bombardment. Debris from the impact would've had a different size distribution than the asteroid belt with a smaller fraction of large celestial bodies, and would result in a lower number of giant impact basins relative to craters.[4]
Properties[]
Planet V is thought to be a terrestrial planet, having a mass less than that of Mars. Assuming that it formed around the time of Mars forming, it can be assumed that Planet V was a molten hell, often impacted by asteroids and debris from the early Solar System, right before it was either sent flying into the Sun, or was sent on a collision course with Mars. Given that the alternate model suggests that Planet V impacted Mars and formed the Borealis Basin, which has been hypothesized to have formed from a collision with an object less than Mars' mass and having a diameter between 1,600 to 2,700 kilometers.[5]
The original hypothesis proposes that Planet V sat over about 1.9 AU away from the Sun, which likely gave it a year length of over 956.5 days, or over 2.619 years.