NASA discovers why 'cotton candy' exoplanets are the size of Jupiter but have low density

NASA‘s Hubble Space Telescope has shed new light on the three ‘cotton candy’ exoplanets orbiting a young sun-like star 2,600-light-years away.

These distant worlds are the size of Jupiter but with a hundred times lighter mass, making them unlike anything that exists in our solar system.

Deemed ‘super-puffs’, experts believe the low density is a result of the exoplanets’ age – they are only 500 million years old, compared to our 4.6-billion-year-old sun.

New data gathered from the telescope suggests their low-density could evaporate over the next few billion years, giving experts a new look to how planets evolve. 

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NASA’s Hubble Space Telescope has shed new light on the three ‘cotton candy’ exoplanets orbiting a young sun-like star 2,600-light-years away. These distant worlds are the size of Jupiter but with a hundred times lighter mass, making them unlike anything that exists in our solar system

The three planets, orbiting a star called Kepler 51, were discovered in 2012 by NASA’s Kepler Telescope, but their low density was not determined until 2014.

Now, the Hubble Telescope is investigating why these super-puffs have a mass that is just several times of Earth, yet the planets are similar to Jupiter in size.

By peering into the atmosphere of each of the exoplanets, the telescope found it is a mixture of helium and hydrogen, making it balloons outward.  

How and why these planet’s atmosphere balloons outwards is a mystery.

The three planets, orbiting a star called Kepler 51, were discovered in 2012 by NASA’s Kepler Telescope, but their low density was not determined until 2014. Their atmosphere is comprised of a hydrogen and helium mixture that makes them puff out like balloons, resulting in their massive size (artist impression) 

However, the team has observed what is happening to the atmospheres – they are evaporating into space.

Experts noted that because the atmosphere is disappearing, the ‘cotton candy’-like stage could be part of a planet’s development and the final product will be something more like a mini-Neptune – the most common type of planet in our galaxy. 

Exoplanet scientist Zachory Berta-Thompson of the University of Colorado Boulder (UC Boulder), said ‘a good bit of their weirdness is coming from the fact that we’re seeing them at a time in their development where we’ve rarely gotten the chance to observe planets.’

The telescope spotted the exoplanets when they passed in front of their star, aiming to observe the infrared color of their sunsets.

Planetary scientist Jessica Libby-Roberts of UC Boulder, said: ‘It definitely sent us scrambling to come up with what could be going on here.’

‘We expected to find water, but we couldn’t observe the signatures of any molecule.’

Astronomers deduced the amount of light absorbed by the atmosphere in infrared light.

This type of observation allows scientists to look for the telltale signs of the planets’ chemical constituents, such as water.

The team did find clouds of particles high in the planet’s atmosphere, but unlike Earth’s water-clouds, these clouds may be composed of salt crystals – similar to those found on Saturn’s moon, Titan. 

WHAT IS THE HUBBLE SPACE TELESCOPE?

The Hubble telescope was launched on April 24, 1990, via the space shuttle Discovery from Kennedy Space Centre in Florida.

It is named after famed astronomer Edwin Hubble who was born in Missouri in 1889.

He is arguably most famous for discovering that the universe is expanding and the rate at which is does so – now coined the Hubble constant. 

The Hubble telescope is named after famed astronomer Edwin Hubble who was born in Missouri in 1889 (pictured)

Hubble has made more than 1.3 million observations since its mission began in 1990 and helped publish more than 15,000 scientific papers.

It orbits Earth at a speed of about 17,000mph (27,300kph) in low Earth orbit at about 340 miles in altitude.

Hubble has the pointing accuracy of .007 arc seconds, which is like being able to shine a laser beam focused on Franklin D. Roosevelt’s head on a dime roughly 200 miles (320km) away.

The Hubble telescope is named after Edwin Hubble who was responsible for coming up with the Hubble constant and is one of the greatest astronomers of all-time

Hubble’s primary mirror is 2.4 meters (7 feet, 10.5 inches) across and in total is 13.3 meters (43.5 feet) long – the length of a large school bus.

Hubble’s launch and deployment in April 1990 marked the most significant advance in astronomy since Galileo’s telescope. 

Thanks to five servicing missions and more than 25 years of operation, our view of the universe and our place within it has never been the same.