A research team at the Geneva University in Switzerland have just discovered what is believed to be the smallest transiting planet detected to date. What makes this discovery all the more interesting is that the researchers believe this planet is composed mostly of "an exotic form of water."

The liquid vapor maintains ice form even at the planet's estimated surface temperature of 300° C, due to high pressure within the atmosphere that compresses the liquid particles closer together.

"Water has more than a dozen solid states, only one of which is our familiar ice," said research team member Frederic Pont. He further explained that much like carbon and diamonds, water can convert into a solid state denser than ice when exposed to extremely high pressures. This was the case found for planet GJ 436, whose external hydrogen-based atmosphere kept its water super-compressed.

GJ 436 was originally discovered back in 2004 using the radial velocity method, where scientists observed the planet's reactions to gravity from its home star. New details were revealed after the researchers used the transit method, where the planet was observed from Earth via telescope as it passes in front of its home star.

The planet is estimated to be about 50,000 kilometres wide - four times the width of Earth - and similar in sized to Neptune, another planet composed mostly of ice. "If you bring Neptune nearer to the Sun and it's heated outside to 300° C, that's exactly what you get," Mr. Pont further noted regarding the two planet's similarities.

Unlike Neptune, the eighth furthest planet from the Sun, GJ 436's orbit around its home star is distance of 13 times closer than Mercury is to our Sun. The research team speculates that the ice and the planet formed farther out from the star long ago and was eventually drawn into its current orbit.

Aside from this discovery of "hot ice", planet experts like Sara Seager at the Massachusetts Institute of Technology state that the discovery is "tremendously exciting" because this was the very first time a planet smaller than a gas giant has been detected using the transit observation method. "It's opening a door to identifying habitable planets in the near future," she commented.