Pluto used to be thought of as the ninth planet in the Solar System, but in 2006 the International Astronomical Union created an official definition for planets and decided Pluto didn’t fit all of the conditions. The upshot was a reclassification of the body discovered by Clyde Tombaugh at Lowell Observatory in 1930, with Pluto being labelled a ‘dwarf planet’ instead. But that’s not to say a ninth planet doesn’t actually exist. In fact, as time goes on, there’s more and more evidence to suggest one is very much out there.
The search for a ninth planet has been ongoing for some time. American astronomer Percival Lowell spent the last decade of his life looking for a hypothetical planet beyond Neptune – the so-called Planet X. It was thought that another planet in the outer reaches of the Solar System would account for the apparent irregularities in the orbits of Uranus and Neptune, and when Pluto was discovered it seemed the search was over.
In 1978, however, Pluto was dismissed as the cosmic influencer because it was too small to have any gravitational influence. Then it was found that Uranus’ orbit only differed from predictions because the calculated mass of Neptune had been incorrect. For a while, the idea that there could be another planet in the Solar System was put on the back burner – that is until scientists searched for a potential explanation for why some of the dwarf planets and other tiny icy objects follow orbits that cluster together. Faced with that conundrum, another planet in the far reaches of the Solar System seemed entirely plausible.
Esta historia es de la edición Issue 157 de All About Space UK.
Comience su prueba gratuita de Magzter GOLD de 7 días para acceder a miles de historias premium seleccionadas y a más de 9,000 revistas y periódicos.
Ya eres suscriptor ? Conectar
Esta historia es de la edición Issue 157 de All About Space UK.
Comience su prueba gratuita de Magzter GOLD de 7 días para acceder a miles de historias premium seleccionadas y a más de 9,000 revistas y periódicos.
Ya eres suscriptor? Conectar
LONG AGO, A LAKE ON MARS MAY HAVE BEEN SPRAWLING WITH MICROBES
Curiosity discovered manganese oxide in bedrock in a Martian region that may have been a shoreline billions of years ago
MOON TOUR HELL
Finding this fascinating crater isnt as hard as its name suggests...
THIS MONTH'S PLANETS
Most of the planets are tricky targets this month, but our guide will help you locate them
UNIVERSE BEFORE TIME
Could the existence of a mirror-image cosmos before the Big Bang solve some of the biggest mysteries in astronomy?
CLIMATE CHANGE IN THE SOLAR SYSTEM
Alongside Earth, our planetary neighbourhood is changing, but it’s not for the better…
Stars give tiny planets a gravitational 'squeeze' to strip away their atmospheres
A scientist has learned more about the violent processes that rip atmospheres away from planets, finding that squashing and squeezing by a parent star can contribute to this process.
The Milky Way's halo is filled with ‘magnetic doughnuts' as wide as 100,000 light years
The outer halo of the Milky Way is filled with magnetic fields that take the shape of vast doughnuts with diameters ranging from 12,000 to 100,000 light years, with the heart of our galaxy at their centre.
The Pentagon wants the commercial space reserve to support military satellites in orbit
The US Department of Defense is developing a plan to use the ever-growing American commercial space industry for national security purposes.
DOES A COSMIC 'GLITCH' IN GRAVITY CHALLENGE ALBERT EINSTEIN'S GREATEST THEORY?
Gravity changes once you reach a cosmic scale
DEEP SKY CHALLENGE : STELLAR TREASURES OF THE ARCHER AND SCORPION
Summer skies are stuffed full of amazing objects for your telescope - if you're prepared to stay up late