Where does water come from?
A new clue has been discovered from distant and foreign worlds.
A group of researchers from the United States found that planets formed dry can become worlds rich in water.
In doing so, the researchers challenge the existing understanding in the field.
The study shows that even planets that formed without water and began as dry and rocky worlds can produce water deep inside them.
Water is essential for life on Earth, but where did it originally come from?
Scientists long believed that water was brought to Earth from far away in the solar system.
Giant icy planets like Uranus and Neptune are located in the outer solar system, where it is cold enough for water to freeze.
According to this idea, water rich objects formed far from the sun and later were delivered to Earth.
In a series of laboratory experiments and computational models, a research team led by Professor Daniel Sims from Arizona State University and Professor Alice Warren showed that many water rich planets were not formed far from their stars and did not need an external supply of ice as previously thought.
Instead, they may have created their own water from the inside out.
The findings blur the line between types of planets.
Dry worlds with a hydrogen envelope and planets covered with water were once considered two separate types of planets.
The new research, published in the journal Nature, shows they may actually be part of the same story stages in the evolution of a planet.
Thanks to NASA’s Kepler mission and other telescopes searching for planets, scientists have discovered thousands of exoplanets planets that orbit other suns in our galaxy.
Two common types are rocky super Earths, which are slightly larger than Earth, and sub Neptunes, which are even larger and have a thick atmosphere.
The fact that there are no such types in our own solar system makes them especially mysterious.
According to Professor Warren, recent observations indicate that some sub Neptunes are water worlds planets with a lot of water while other sub Neptunes are dry rocky planets with a hydrogen atmosphere.
The surprise is that many of the water worlds are located very close to their stars, where it should be too hot for water to condense or survive.
In a series of laboratory experiments, the researchers used high power lasers and a diamond anvil cell to create the extreme heat and pressure found inside sub Neptune planets.
They then monitored what happened when hydrogen gas came into contact with hot rocky materials using X rays.
Their results show that water can form through chemical reactions from dry material.
Hydrogen from the atmosphere reacted with oxygen released from the rocks and produced water. Even planets that formed without water that began as dry rocky worlds with thick hydrogen envelopes could produce water deep inside them.
Computer simulations found that the water created spreads efficiently inside the planet, allowing ongoing water production.
This discovery suggests that many water rich planets were not formed far from their stars and did not need an external supply of ice as previously believed.
According to Professor Sims, this shows that planets can create one of the key ingredients for life water even in hot environments close to stars.
Professor Warren adds that these findings require a fresh look at the accepted theory of planets formed with hydrogen envelopes.
While the high temperatures near stars may still make life unlikely, the research shows that water may be far more common in the universe than previously thought.