Astronomers Find Two Giant "Cotton Candy Planets" Lighter Than Air

Professor Pip adjusted his crooked spectacles and patted the bulging pockets of his green lab coat. "Ah-ha! Just the thing." Out came a fluffy pink puff of cotton candy — and out of the other pocket, a tiny glass jar with a small silver bearing inside.

Mia and Leo leaned in close at the workbench. Through the lab window, the stars were just beginning to twinkle on.

"Tonight," Pip whispered, his tail giving a happy swish, "we're going to learn about fluffy planets."

"Fluffy planets?!" Leo's mouth fell open.

"Like, made of clouds?" asked Mia.

"Not quite. Watch carefully." Pip held out both paws. "This piece of cotton candy is much bigger than this little silver ball. Which one do you think is heavier?"

"The cotton candy!" said Leo. "It's huge!"

Pip placed each one carefully on his little brass scale. PLINK went the silver ball. The cotton candy barely tipped the scale at all. Leo gasped.

"Oh my whiskers," Pip whispered. "The big puffy one is much lighter! Because cotton candy is mostly tiny strings of sugar with lots of air in between. That's what we call density — how much stuff is squished into a space. The cotton candy is huge but low-density. The silver ball is small but very dense."

He pointed up through the window. "Now. Far, far away — a thousand light-years from us — astronomers just found two planets as big as Jupiter. But you know what?"

"What?" the children whispered.

"They're lighter than this cotton candy."

"WHAT?!"

"It's true! They are puffy giants — huge balls of gas and dust with so much room between the bits that if you could plop one into a swimming pool the size of the solar system, it would float."

"Oh!" said Mia, eyes shining. "Like a big balloon with just a little tiny weight in it!"

"Exactly right!" Pip's tail swished madly. "Precisely the idea." He gazed up at the night sky. "Out there are worlds so light they would drift if you tossed them. Imagine that, my fellow scientists."

He handed each child a little wad of cotton candy. "Now you try. See how a big thing can be very, very light. Now I wonder… could a planet ever be lighter than that?"