In astronomy, first light is the first use of a telescope to take an astronomical image after it has been constructed. This is often not the first viewing using the telescope; optical tests will probably have been performed to adjust the components.
The Sun in the first light image from the IRIS satellite
Very Large Telescope's wide field imager VIMOS takes its first light image of NGC 5364.
First light of the Tarantula Nebula by TRAPPIST
Image: Webb's First Deep Field
A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally it was an optical instrument using lenses, curved mirrors, or a combination of both to observe distant objects – an optical telescope. Nowadays, the word "telescope" is defined as a wide range of instruments capable of detecting different regions of the electromagnetic spectrum, and in some cases other types of detectors.
The 100-inch (2.54 m) Hooker reflecting telescope at Mount Wilson Observatory near Los Angeles, USA, used by Edwin Hubble to measure galaxy redshifts and discover the general expansion of the universe.
17th- century telescope
Three radio telescopes belonging to the Atacama Large Millimeter Array
Hitomi telescope's X-ray focusing mirror, consisting of over two hundred concentric aluminium shells
