A planet thrice the size of Jupiter discovered due to its 'strange orbit'

A planet thrice the size of Jupiter discovered due to its 'strange orbit'
HR 5138's 'highly eccentric' orbit in comparison to the circular orbits of our solar systemKeck Observatory

  • Astronomers at California Planet Search have found a new planet that's three times the size of Jupiter in the outer reaches of the universe.
  • It took twenty years of observations to determine the planet's 'highly eccentric' orbit which sling-shots itself around its star.
  • The planet dubbed HR 5138 is the first exoplanet to exhibit such behaviour.
The outer reaches of the universe holds many mysteries. But scientists from California Planet Search discovered an exotic planet which has a wonky 'sling-shot' like orbit which gets close to its star around its star before swinging around and getting further away.

Exoplanets aren't known for planets that 'slingshot' around their stars but the planet dubbed HR 5183 b, which is three times the size of Jupiter, in an exception to the rule.

In fact, it was the planet's weird path that caught the attention of astronomers at the Keck Observatory. It paved the way for the discovery of other giant planets that might be behaving in a similar manner.

Instead of going around in a flat circle, HR 5138 b has an elliptical orbit that isn't equidistant from its star on all sides.

A planet thrice the size of Jupiter discovered due to its 'strange orbit'
HR 5138 b's elliptical orbitKeck Observatory


Twenty long years of waiting and watching

It took 20 years of observations to figure out that the planet has an 'highly eccentric' orbit because it only circles its star every 45 to 100 years.

"This planet spends most of its time loitering in the outer part of its star's planetary system in this highly eccentric orbit, then it starts to accelerate in and does a slingshot around its star," explains Andrew Howard, an astronomy professor at Caltech.

If the planet was placed in our solar system, it would swing from our asteroid belt to beyond Neptune — covering approximately 3.7 million kilometers — according to a study published in The Astronomical Journal.

No influence

Scientists initially assumed that the HR 5138 b's wonky orbit was because another planet might be exerting its gravitational influence.

But that wasn't the case.

They now believe that the planet probably had a neighbour of similar size. Both the planets would have originally had flat and circular orbits. But, getting too close to each other, one pushed the other out of the solar system causing the HR 5138's slingshot orbit.

"This newfound planet basically would have come in like a wrecking ball — knocking anything in its way out of the system," said Howard.

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