When scientists announced earlier this year that they might have discovered a ninth planet in Earth’s solar system, the finding brought comfort to those of us still mourning Pluto’s downgrade to “dwarf planet.” But new research out of the University of Warwick shows that the mysterious “Planet Nine,” which is believed to circle the sun once every 15,000 years, could eventually spell disaster for our solar system.
While it sounds terrifying, don’t get too worried – by the time Planet Nine could become a threat, the sun will have died of natural causes and Earth will no longer be habitable. Hopefully, humanity will have moved on to a new home already. It all has to do with the lifecycle of our solar system, according to physicist Dr. Dimitry Veras. Roughly seven billion years from now, our sun will begin to die – inflating to a huge size as its mass begins to blow away. This enormous fireball will swallow the inner planets, including the Earth, before the star fades back into a smoldering ember known as a “white dwarf.” At this point, the sun will have shrunk down to a dense star about the same size as the Earth.
In the past, scientists believed the outer planets of the solar system would survive this shift, continuing to orbit at a safe distance. Not a happy end for Earth or the inner planets, perhaps, but certainly not the death of the solar system itself. However, Dr. Veras has projected that the presence of a large planet beyond the known reaches of our solar system could cause some of the surviving giant planets to be ejected into space instead.
When the sun expands and becomes a red giant billions of years in the future, the four known gas giants will be pushed further out into the solar system – however, Planet Nine, which has been estimated to be 10 times more massive than Earth – may not experience the same shift. Instead, it might find itself thrust inward, interfering with the orbits of Uranus and Neptune, potentially tearing apart the solar system as we know it.
It’s important to stress that this is still a hypothetical scenario. While scientists are fairly certain that Planet Nine exists due to the observed influence on orbiting objects near Neptune, it hasn’t been visually confirmed by telescope. That means we don’t know exactly how far out it might be located – and according to Dr. Vargas, the location is crucial. The further out Planet Nine may be orbiting, he says, the likelier it is that the solar system will meet a violent end.
Dr. Vargas’ findings will be published in the Monthly Notices of the Royal Astronomical Society.