near infrared

Near infrared (NIR or near-IR) is infrared radiation adjacent to visible light within the electromagnetic spectrum, with wavelengths 750-2500 nm (all infrared's range being 750 nm to 1 mm; slightly different ranges are also cited for these). The essential difference between NIR and visible light is that NIR's wavelength is just outside the range of human vision and the optical equipment for NIR is largely the same as that for visible light and modern research optical telescopes typically can observe at some or all NIR wavelengths as well. Sources producing visible light generally produce some NIR, and some sources are at distances such that redshift moves their visible light into the NIR band. Among the uses for NIR astronomy is the study of cool ("late") stars. Also, of use is that NIR is less affected by dust than visible light: objects hidden in dusty nebulae might be observed in infrared. A disadvantage of NIR observation is that some of its wavelengths are blocked by the atmosphere, and ground observation is confined to a few spectral bands within which the atmosphere is transparent to NIR (atmospheric windows). Observation from a high altitude reduces this issue.