Ethyl alcohol and sugar in comet C/2014 Q2 (Lovejoy).

The presence of numerous complex organic molecules (COMs; defined as those containing six or more atoms) around protostars shows that star formation is accompanied by an increase of molecular complexity. These COMs may be part of the material from which planetesimals and, ultimately, planets formed. Comets represent some of the oldest and most primitive material in the solar system, including ices, and are thus our best window into the volatile composition of the solar protoplanetary disk.

Cometary science. Subsurface properties and early activity of comet 67P/Churyumov-Gerasimenko.

Heat transport and ice sublimation in comets are interrelated processes reflecting properties acquired at the time of formation and during subsequent evolution. The Microwave Instrument on the Rosetta Orbiter (MIRO) acquired maps of the subsurface temperature of comet 67P/Churyumov-Gerasimenko, at 1.6 mm and 0.

Localized sources of water vapour on the dwarf planet (1) Ceres.

The 'snowline' conventionally divides Solar System objects into dry bodies, ranging out to the main asteroid belt, and icy bodies beyond the belt. Models suggest that some of the icy bodies may have migrated into the asteroid belt. Recent observations indicate the presence of water ice on the surface of some asteroids, with sublimation a potential reason for the dust activity observed on others.

Ocean-like water in the Jupiter-family comet 103P/Hartley 2.

For decades, the source of Earth's volatiles, especially water with a deuterium-to-hydrogen ratio (D/H) of (1.558 ± 0.001) × 10(-4), has been a subject of debate.

New trends in cometary chemistry.

This paper presents some of the implications of new comet observations for cometary chemistry: recent observations of bright comets, space missions, and especially the first results of the Deep Impact experiment. Topics which are discussed are the molecular complexity of cometary material, the evidence for molecular diversity from the infrared observations by Deep Impact, possible relations between cometary nuclei and carbonaceous chondrites, the sites of ices in cometary nuclei, the problem of interpretation of the spin temperatures observed in cometary molecules.