workhorse instrument for spectroscopy. METIS: The Mid-infrared ELT Imager and Spectrograph (METIS) will be a mid-infrared imager and spectrograph. MICADO: The Multi-AO (adaptive optics) Imaging Camera for Deep Observations (MICADO) will be the first dedicated imaging camera for the ELT and will work with the Multi-conjugate Adaptive Optics RelaY, (MAORY). The second generation of instruments consists of MOSAIC and ANDES: MOSAIC: A proposed multi-object spectrograph which will allow astronomers to trace the growth of galaxies and the distribution of matter from shortly after the Big Bang to the present day. ANDES (formerly HIRES): The ArmazoNes high Dispersion Echelle Spectrograph will be used to search for indications of life on Earth-like exoplanets, find the first-born stars of the universe, test for possible variations of the fundamental constants of physics, and measure the acceleration of the Universe's expansion. Comparison One of the largest optical telescopes operating today is the Gran Telescopio Canarias, with a 10.4 m aperture and a light-collecting area of 74 m2. Other planned extremely large telescopes include the 25 m/368 m2 Giant Magellan Telescope and 30 m/655 m2 Thirty Meter Telescope, which are also targeting the second half of the 2020 decade for completion. These two other telescopes roughly belong to the same next generation of optical ground-based telescopes. Each design is much larger than previous telescopes. The size of the ELT has been reduced from its original design. But even with this reduction, the ELT is significantly larger than both other planned extremely large telescopes. It has the aim of observing the universe in greater detail than the Hubble Space Telescope by taking images 15 times sharper, although it is designed to be complementary to space telescopes, which typically have very limited observing time available. The ELT's 4.2-metre secondary mirror is the same size as the primary mirror on the William Herschel Telescope, the second largest optical telescope in Europe. The ELT under ideal conditions has an angular resolution of 0.005 arcsecond which corresponds to separating two light sources 1 AU apart from distance, or two light sources 30 cm apart from roughly 12,000 km distance. At 0.03 arcseconds, the contrast is expected to be 108, sufficient to search for exoplanets. The unaided human eye has an angular resolution of 1 arcminute which corresponds to separating two light sources 30 cm apart from 1 km distance. Stills The images below show artistic renderings of the ELT and were