First Molecule

"Astronomers have spotted the universe's first molecule":

Helium hydride (HeH), a combination of helium and hydrogen, was spotted some 3000 light-years from Earth by an instrument aboard the airborne Stratospheric Observatory for Infrared Astronomy (SOFIA), a telescope built into a converted 747 jet that flies above the opaque parts of Earth’s atmosphere.

HeH has long been thought to mark the “dawn of chemistry,” as the remnants of the big bang cooled to about 4000 K and ions began to team up with electrons to form neutral atoms. Researchers believe that in that primordial gas, neutral helium reacted with hydrogen ions to form the first chemical bond joining the very first molecule.