Newly detected molecules in dense interstellar clouds.

The last year or so has seen the identification of several new interstellar molecules, including C2S, C3S, C5H, C6H, and (probably) HC2CHO in the cold, dark cloud TMC-1; and the discovery of the first interstellar phosphorous-containing molecule, PN, in the Orion "plateau" source. Further interesting results include the observations of 13C3H2 and C3HD, and the first detection of HCOOH (formic acid) in a cold cloud.