Mystery of Planet 9

How The Universe Works

Scientists have discovered a mysterious ninth planet on the very edge of our solar system. Perhaps ten times the size of Earth, this strange world could have moons with extraterrestrial life.

The hunt for Planet 9 started when astronomers realized that Uranus and Neptune’s orbits had irregularities. This came to light only after the Voyager 2 fly-by of these planets in 1986 and ’87.

Further observations of these orbits led astronomers on a wild chase to find this new elusive planet, later named “Planet 9”.

Today, 3 years after the airing of this documentary, scientists at the California Institute of Technology in Pasadena has shown the evidence for Planet 9 being very real – backed by astronomy studies from the last two decades.

It is likely that if Planet Nine exists, it will be discovered within the coming decade.

Konstantin Batygin at the California Institute of Technology in Pasadena (6 march, 2019)

The evidence entails discoveries of numerous small bodies orbiting beyond Neptune. Many of these have highly elliptical orbits which take them out to the outer reaches of our solar system.

By tracking these trans-Neptunian objects far out into the Kuper Belt region, gravitational pulls and irregular orbits are observed.

So what type of planet is planet 9? Although better observations will tell better than any hypothesis, some guesses have been made.

One possibility is that Plant 9 is a dwarf star orbiting many thousands of times farther away than Earth.

But this has been ruled out by infrared surveys looking for such an object. Neither can Planet 9 be Saturn-size or bigger, because we ought to have spotted an object that big by now.

Scientists speculate that Planet 9 must have a mass between 5 and 10 times that of Earth. It must orbit the sun between 400 and 800 times farther away than Earth. And its orbit must be inclined to the plane of the solar system by between 15 and 25 degrees.

Given that level of detail, it’s easy to imagine these scientists can point to an area of sky and say, “Look there.” Not so. Finding it is likely to require a dedicated survey using some of the world’s biggest telescopes.

Another possibility could be that all of these observations have been a fluke, a chance alignment at the precise moment when astronomers happened to be looking.

Mystery of Planet 9
  • Info
  • Release date23 Nov., 2016
  • Full runtime42 min
  • From the seriesHow The Universe Works: season 5 episode 1
  • Narrated byMike Rowe
  • Produced byDiscovery Channel, Pioneer Productions
  • Produced forDiscovery Communications