Fast-changing sodium gas around the 5.4-million-year-old star PDS 70 provides evidence that icy exocomets may be plunging into the young system’s inner regions. Computer simulations show that giant planets could scatter planetesimals inward from beyond 54 astronomical units, potentially carrying water and other volatile materials toward forming rocky worlds. The exocomet interpretation remains unconfirmed, but if verified, PDS 70 would be the youngest planetary system known to show this kind of comet activity. A young planetary system 370 light-years away may be showing astronomers something remarkably familiar: icy comets carrying water toward the region where rocky planets could eventually emerge. Astronomers at Lund University in Sweden have found fast-changing clouds of sodium gas around PDS 70, a 5.4-million-year-old star already famous for its actively forming planets. The signals behave much like material released by comets passing close to a star, raising the possibility that frozen bodies from the system’s distant outskirts are being hurled inward. The findings, published in Nature Communications, offer a possible explanation for water vapor previously detected close to the star. The …