The Extremely Large Telescope will supercharge our view of the cosmos

A colossal advancement in astronomy is on the horizon: the Extremely Large Telescope (ELT). Comparable to a Godzilla movie in its monumental scale, this telescope is set to revolutionize the understanding of the universe. If the James Webb Space Telescope has impressed you, the ELT will be even more astonishing.

Understanding telescopes starts with recognizing that size is paramount. While many believe a telescope’s main function is magnification, its primary purpose is to collect light. Distant light sources appear dimmer due to the inverse square law; for example, a lightbulb moved ten times further away seems 100 times fainter. Telescopes function as "light buckets," capturing as many photons as possible from distant objects to produce a clear signal amid background noise.

The light-collecting power of a telescope is proportional to the square of its mirror’s diameter. A 10-meter mirror collects 100 times more light than a 1-meter mirror, making large mirrors highly desirable. Enter the ELT, with mirrors almost 40 meters across, supported by a frame the size of a football field. This structure includes a secondary mirror to redirect light to various instruments and is housed within a record-breaking 74-meter-high and 86-meter-wide dome, totaling 9,000 tons.

Constructing the ELT in Chile’s Atacama Desert, one of the driest places on Earth, is essential for its operation in optical and near-infrared wavelengths. The location’s high altitude and arid conditions minimize atmospheric interference, making it ideal for such an advanced telescope.

The ELT's unprecedented light-collecting power—100 million times greater than the human eye and over ten times that of existing telescopes—will transform astronomy. It will enable direct detection of light from Earth-like exoplanets, a significant leap in astrobiology. The ELT will separate light from planets and their host stars with a precision of one part in a billion at 0.1 arcseconds, facilitating detailed characterization of exoplanets and potential signs of life.

Beyond exoplanets, the ELT will advance the understanding of galaxies, cosmology, and star formation. The anticipation for its "first light" in 2028 is palpable, marking the beginning of a new era in astronomical discovery. Keep an eye on this groundbreaking project as it nears completion.