The Allsea eyes, operational since the 2070s, were the largest and most powerful optical systems ever constructed. Comprising eight telescopes dispersed across the lunar expanse, each equipped with a 100-meter mirror, the collective aperture of this composite telescope spanned the entire lunar surface, enabling exceptional imaging capabilities.

This marked the first occasion we could observe the “first light,” indicating the birth of the universe’s first star. We also captured details of distant exoplanet surfaces across great expanses of time.

In 2020, numerous proposals emerged for these ambitious, next-generation telescopes; however, the technological feasibility for large-scale space projects was limited at that time. By the 2050s, lunar transport became routine and economically viable, paving the way for lunar construction.

An earlier proposal from 2020 focused on what was termed Finally, a large telescope (ULT), with a mirror measuring 100 meters, came to fruition.

ULT utilized liquid mirrors instead of traditional glass. These liquids were more cost-effective to transport to the moon and could be molded into completely reflective surfaces. Given the moon’s gravity, constructing larger mirrors that exceed those on Earth became practical. For comparison, the James Webb Space Telescope, operational in the 2020s, features a 6.5-meter mirror.

While the lunar single telescope was powerful, it lacked the resolution to distinguish the detailed features of exoplanet bodies. Nonetheless, astronomers focused on expanding ULT’s capabilities.

A clever technique used in radio telescopes to enhance their range, Very Long Baseline Interferometry (VLBI), proved suitable for optical systems as well. In 2017, the Event Horizon Telescope Collaboration employed VLBI to capture the first image of a supermassive black hole at the center of our galaxy by merging inputs from eight Earth-based telescopes to amplify the effective telescope size.

In 2025, scientists spearheaded by Zixin Huang at the Engineering Quantum Systems Center at Macquarie University, Australia, proposed using VLBI for optical telescopes. Although technical, political, and financial barriers prolonged development, the advent of the first 100-meter diameter telescope in lunar craters by 2050 led to serious initiatives for constructing a lunar-sized optical telescope.

By 2075, an additional seven telescopes were established on the lunar surface, linking to form an effective aperture equivalent to a 3000 km mirror.

In the mid-2020s, the James Webb Telescope revisited the past to observe the formation of the universe’s first galaxy. Now, through the combined observations, the enigmatic Population III stars have been unveiled. Stars are categorized into different groups; Population I contains recent stars abundant in heavy elements, Population II includes older stars with lower metal content, while Population III consists of the universe’s earliest stars formed post-Big Bang, characterized by minimal metallic content. The Big Bang primarily produced hydrogen and helium, with mere traces of lithium and beryllium. All heavier elements had to be synthesized in stars. The combined observations have looked back 13 billion years and documented the high-mass first-generation stars, including one blue giant star, 100,000 times the mass of the sun, dubbed Zixin-1 in honor of the astronomer who significantly contributed to the development of optical VLBI.

The moon-sized telescope concept has been referred to by various names over the years. Initially proposed in 2008 by a team from the University of Arizona, the lunar liquid spraying telescope eventually evolved into a larger project in 2020. To escape the possibly uninspired public names like Moony McMoonface, the term “Allsea Eyes” was officially adopted. The project is now affectionately dubbed Sauron: Super-Accessible Ultra-Resolution Optical Network.

The facility has enabled unprecedented imaging of black holes, but its primary objective was to determine if humanity is alone in the universe. The observations made of the exoplanet Gliese 667cc indicated the potential for alien civilizations to have developed in our cosmic neighborhood, particularly within the Trappist-1 system, about 22 light-years away. Despite debates surrounding the costs of constructing Sauron, they never gained significant traction.

Rowan Hooper is the podcast editor for New Scientist and the author of How to Spend $1 Trillion. These are 10 global issues that can be fixed. Follow him on BlueSky
@rowhoop.bsky.social