Make way for MOTHRA, the world’s largest all-lens telescope, which intends to detect some of the faintest light in the universe.
Co-created by Yale astronomer Pieter van Dokkum and University of Toronto astronomer Roberto Abraham, the new telescope is now under construction at the Obstech/El Sauce Observatory in Chile’s Rio Hurtado Valley and builds upon design concepts from van Dokkum and Abraham’s groundbreaking Dragonfly Telescope. That telescope, located in the mountains of New Mexico, combines images from multiple lenses to detect the dim glow of faint stars and galaxies.
MOTHRA will have a different mission. Its array of 1,140 telephoto lenses — the equivalent of a single 4.7-meter diameter lens — will look for diffuse ionized gas located in-between galaxies.
Rendering of part of the MOTHRA telescope. Each of the mounts has 38 high-end Canon telephoto lenses, equipped with special filters to observe the cosmic web. The completed telescope will have 30 mounts, in two buildings, with a total of 1,140 lenses. All the lenses look at the same patch of sky, together creating a telescope that behaves like a giant single lens with a diameter of 4.8 meters.
“All galaxies are connected by a giant web of unseen cosmic matter,” said van Dokkum, the Sol Goldman Family Professor of Astronomy and professor of physics in Yale’s Faculty of Arts and Sciences. “We want to construct a telescope to take the first picture of it.”
Van Dokkum and Abraham designed the original Dragonfly telescope in 2013 with three telephoto lenses that worked together as a wide-field, large aperture telescope. Dragonfly grew to 48 lenses and has yielded data for dozens of scientific studies.
Among other phenomena, Dragonfly has discovered a new population of ultra-diffuse galaxies and extended galaxy halos around nearby galaxies.
But van Dokkum and Abraham didn’t want to stop there.
“We had this idea of using the lenses to look at gas, rather than stars,” van Dokkum said. “Gas can show you where the dark matter is.”
Dark matter, a theorized material thought to make up the majority of all matter in the universe, has never been seen. Researchers believe it acts as a scaffolding, or web, upon which galaxies form and evolve.
“It’s our origin story, the engine by which galaxies in the universe grow,” van Dokkum said. “Yet it’s been so hard to study.”
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1 / 3The galaxy NGC 253, also known as the Sculptor Galaxy, observed with MOTHRA in the light of ionized hydrogen. In NGC 253 about 10 new stars are born every year, five times more than in the Milky Way. MOTHRA is equipped with unique, tiltable filters that can observe different wavelengths of light. The different colors show the rotation of the galaxy, with the purple side coming towards us and the orange side moving away from us. Faint tendrils of light to the upper right show where gas has been lifted out of the galaxy.
Credit: Team MOTHRA -
2 / 3MOTHRA observing at night. Each mount is equipped with a wide area web cam. Besides the mount in the foreground two others are visible. The skies at El Sauce Observatory in Chile are among the best on Earth for astronomy. The Milky Way is clearly visible, as well as the Large Magellanic Cloud, the patch just right of center. The Large Magellanic Cloud is a neighboring galaxy of the Milky Way.
Credit: Team MOTHRA -
3 / 3The nebula RCW 114, also known as the Dragon’s Heart Nebula, was one of the first objects that MOTHRA looked at. It is the remnant of a star that exploded as a supernova about 20,000 years ago. The MOTHRA image is in the light of ionized hydrogen and spans an area of sky that is 250 times larger than the full moon.
Credit: Team MOTHRA
He and Abraham estimated they would need perhaps 10 times more lenses — plus new filters and more computing power — to see the cosmic web. Luckily for them, someone with the resources to help fund such an endeavor was eager to help.
Alex Gerko, the founder and CEO of the algorithmic trading firm XTX Markets, is funding the project. Gerko also partnered with van Dokkum and Abraham on other aspects of the project, including site selection and procurement. The group worked with a non-profit organization, Convergent Research, to set up Dragonfly FRO — a “focused research organization” designed to build high-impact scientific infrastructure at the pace of a tech startup.
“This is an ambitious project to build something astronomers have wanted for a long time: a practical way to directly see the cosmic web in emission, and to get it done in a couple of years rather than decades,” Abraham said. “MOTHRA harnesses advances in optics, detectors, and computing power to look at the universe in a new way.”
MOTHRA also benefits from Yale-patented tilting filters that enable detection of low surface brightness objects that are otherwise difficult to detect with conventional mirror-based telescopes.
The new telescope will be able to see not only where gas is, but how it moves within the web.
Construction on MOTHRA began in January 2025. The researchers expect the telescope to be fully operational by the end of the year.
