Hubble captures birth of giant storm on Neptune: NASA

In a first, the Hubble Space Telescope has beamed back images documenting the birth of a giant storm on Neptune, a finding that may reveal insights on the inner workings of the poorly-understood ice giant planets, NASA said.

Like Jupiter's Great Red Spot, Neptune's Great Dark Spots are storms that form from areas of high atmospheric pressure. In contrast, storms on Earth form around areas of low pressure.

Scientists have seen a total of six dark spots on Neptune over the years. Voyager 2 identified two storms in 1989. Since Hubble launched in 1990, it has viewed four more of these storms, NASA said in a statement.

Researchers analysed Hubble's photos of the ice giant taken over the past several years and chronicled the growth of a new Great Dark Spot that became visible in 2018.

By studying companion clouds that showed up two years before the new Great Dark Spot, the researchers conclude dark spots originate much deeper in Neptune's atmosphere than previously thought.

The Hubble images also helped the researchers pinpoint how often Neptune gets dark spots and how long they last.

The findings not only give scientists insights on the inner workings of the ice giant planets but also have implications for studying exoplanets of similar size and composition.

"If you study the exoplanets and you want to understand how they work, you really need to understand our planets first," said Amy Simon, a planetary scientist at NASA's Goddard Space Flight Center in the US.

"We have so little information on Uranus and Neptune," said Simon, lead author of the study published in journal Geophysical Research Letters.

Scientists first saw a Great Dark Spot on Neptune in 1989, when NASA's Voyager 2 probe flew past the mysterious blue planet. As the spacecraft zoomed by, it snapped pictures of two giant storms brewing in Neptune's southern hemisphere.

Scientists dubbed the storms "The Great Dark Spot" and "Dark Spot 2."