The European Extremely Large Telescope

The world's biggest eye on the sky

Extremely Large Telescopes are considered worldwide as one of the highest priorities in ground-based astronomy. They will vastly advance astrophysical knowledge, allowing detailed studies of subjects including planets around other stars, the first objects in the Universe, super-massive black holes, and the nature and distribution of the dark matter and dark energy which dominate the Universe.

Since the end of 2005 ESO has been working together with its user community of European astronomers and astrophysicists to define the new giant telescope needed by the middle of the next decade. More than 100 astronomers from all European countries have been involved throughout 2006, helping the ESO Project Offices to produce a novel concept, in which performance, cost, schedule and risk were carefully evaluated.

Dubbed E-ELT for European Extremely Large Telescope, this revolutionary new ground-based telescope concept will have a 39-metre main mirror and will be the largest optical/near-infrared telescope in the world: “the world’s biggest eye on the sky”.

Science with the E-ELT

With the start of operations planned for early in the next decade, the E-ELT will tackle the biggest scientific challenges of our time, and aim for a number of notable firsts, including tracking down Earth-like planets around other stars in the "habitable zones" where life could exist — one of the Holy Grails of modern observational astronomy. It will also perform "stellar archaeology" in nearby galaxies, as well as make fundamental contributions to cosmology by measuring the properties of the first stars and galaxies and probing the nature of dark matter and dark energy. On top of this astronomers are also planning for the unexpected — new and unforeseeable questions will surely arise from the new discoveries made with the E-ELT.

Science goals

General purpose extremely large aperture optical/infrared telescope. Some science areas are to be high redshift galaxies, star formation, exoplanets and protoplanetary systems.

Live image

Follow Cerro Armazones on this live image taken from Cerro Paranal. It is updated every hour during daytime. Click on it to enlarge.

More about the Extremely Large Telescope

  • More interesting facts are available on the FAQs page
  • More images and videos are available in the ESO multimedia archive
  • Read more on about this telescope on:
  • For Scientists: for more detailed information, please see our technical pages
  • Watch the trailer

    Download this trailer in other formats from the Video Archive.


    A Tour at Cerro Armazones

    Virtual Tour at Cerro Armazones

    Click on the image to take a Virtual Tour in and nearby Cerro Armazones.



    Name: European Extremely Large Telescope
    Site: Cerro Armazones
    Altitude: 3060 m
    Enclosure: Hemispherical dome
    Type: Optical/near-infrared Giant Segmented Mirror Telescope
    Optical design: Five-mirror design — three-mirror on-axis anastigmat + two fold mirrors used for adaptive optics
    Diameter. Primary M1: 39 m (798 hexagonal 1.4 m mirror segments)
    Material. Primary M1: Not decided yet
    Diameter. Secondary M2: 4 m
    Material. Secondary M2: Not yet known
    Diameter. Tertiary M3: 3.75 m
    Mount: Alt-Azimuth mount
    First Light date: Early 2020s
    Active Optics: Yes
    Adaptive Optics: 2.60 m adaptive M4 using 6 Laser Guide Stars
    Images of the E-ELT: Link
    Press Releases with the E-ELT: Link


    Did you know?
    The E-ELT will gather 100 000 000 times more light than the human eye, 8 000 000 times more than Galileo's telescope, and 26 times more than a single VLT Unit Telescope. In fact, the E-ELT will gather more light than all of the existing 8–10-metre class telescopes on the planet, combined.