An "extremely unusual" planet, with summer temperatures above 2,000 degrees and aluminium rain in winter, is teaching scientists how some of the hottest known gas giants were formed.
A team of international researchers, led by Pennsylvania State University, discovered the gaseous exoplanet TOI-3362 b about 200 light years from Earth.
University of Southern Queensland astronomer Dr George Zhou was part of the team that recently confirmed the discovery. He said the planet's summer was significantly hotter than its winter.
"The winter here on this planet is not that cold — about 500 degrees — but the summer is blazingly hot," he said.
"That's because this planet orbits its star in a very strange orbit.
"It comes very close to the star during summer and then goes really far away during the winter. "
He said the phenomenon known as an elliptical orbit caused the planet's extreme seasons.
"We've only discovered a couple of these planets before," Dr Zhou said.
"The Earth has a very circular orbit and so do the giant planets like Jupiter and Saturn.
"Elliptical orbiting planets in our own solar system, like Mercury or Pluto, are generally not as extreme as the planet we have here.
"In this case, we have an elliptical orbit that brings the planet about nine times as close to the host as it is at its furthest point."
One year on TOI-3362 b lasts approximately 18 days and the planet has roughly five times the mass of Jupiter.
'Missing link'
Dr Zhou said the planet's unusual orbit was helping scientists piece together the origins of planets known as "hot Jupiters", which orbit very close to their stars.
"Some of the very first [hot Jupiters] that we've discovered as a community really shocked us. They looked nothing like the planets in our own solar system," he said.
"We think that this planet is the missing link between planets that orbit very close to their stars ... and planets in our own solar system.
"[TOI-3362 b] will turn into a hot Jupiter, but we're going to have to give it about five billion years or so."
The extreme temperature difference is thought to cause aluminium in the planet's atmosphere to evaporate and form clouds in summer, which produce rain in winter.
Dr Zhou said the planet would be a target for further atmospheric research when NASA's new James Webb Space Telescope is launched in the next year.
"It's very distant, but it's actually considered in the solar neighbourhood," he said.
"Unfortunately, we won't be able to visit it anytime soon.
"But it does mean that we can use large telescopes here on Earth to study its properties."
Global effort
Pennsylvania State University graduate Jiayin Dong led the research, using data from the Mount Kent Observatory in southern Queensland to confirm the orbit of the planet, after it was picked up by NASA's Transiting Exoplanet Survey Satellite.
USQ PhD student Alexis Heitzmann said the global collaboration, along with the planet's short orbit, made the planet's discovery and confirmation a swift process.
"In two months we knew it was there and everyone was really excited because when we saw the shape of the orbit [we knew] it was something really, really special," he said.
"We are really hopeful and confident that this is the first of many [collaborations]."