The observation of electromagnetic waves from the Universe at wavelengths of about 1–10 mm, a part of the spectrum rich in lines emitted by interstellar molecules. Millimetre-wave astronomy is one of the newest fields in astronomy and is used to study the chemistry of interstellar matter, and the complex processes in star-forming regions and dark clouds. The cosmic microwave background is brightest in this part of the spectrum. Major millimetre-wave facilities include those of the Institut de Radio Astronomie Millimétrique (IRAM) and Nobeyama Radio Observatory. See also Submillimetre Astronomy.
Subjects: Astronomy and Astrophysics.