Interstellar Environments

The tiny grains of silicate and carbon — often coated in mantles of ice — that pervade the interstellar medium. They redden and dim starlight, radiate in the infrared, and, crucially, provide the surfaces on which many molecules are built.

Cold, dense clouds of molecular hydrogen and dust, dark and shielded from starlight, where nearly all the interstellar molecules reside and where stars are born. They are the richest chemical factories in the galaxy, mapped in the millimetre and submillimetre.

The disks of gas and dust that surround young stars, out of which planets, moons, and comets form. Their chemistry — imaged in exquisite detail by ALMA — sets the raw ingredients that new planets and their atmospheres are built from.

The dense cores of molecular clouds where gravity pulls gas together into new stars, and where the heat and radiation of those young stars drive a burst of chemistry. The Orion Nebula is the nearest region of massive star formation and the most-studied example.

The thin, warm, mostly atomic gas that fills the space between the stars, laced with dust that reddens the light passing through it. Even here, exposed to starlight, the first simple molecules form — the beginning of cosmic chemistry.