Astronomers have gotten a rare glimpse at four baby planets as they're growing up, and it reveals something surprising: These toddler worlds are getting lighter as they age.
The quadruplet worlds orbit in tightly packed paths around the star V1298 Tau, a young system that's just 20 million years old (compared with our sun's 4.5 billion years) located about 350 light-years from Earth. A new analysis, which drew on a decade of observations, shows that the planets are surprisingly lightweight, with low densities — so puffed up, in fact, that researchers likened them to Styrofoam.
