How to build a telescope larger than the planet Earth
In short: To see the smallest details of the universe, we need bigger lenses. But building a physical mirror the size of a planet is impossible. Instead, scientists use a clever workaround: they link separate telescopes across vast distances to act as one giant eye.
The fundamental limit of any telescope is its aperture—the diameter of its primary lens or mirror. To achieve higher resolution and capture finer details, an instrument must be larger. However, physical constraints make building a single dish the size of a planet impossible. The solution lies in interferometry: combining multiple telescopes located far apart to simulate the resolution of a single, massive collector. This method overcomes the physical limits of optics by combining global assets. It allows for resolution that would otherwise be unreachable with conventional hardware.
A prime example is the Event Horizon Telescope (EHT). In 2019, this network of eight radio observatories distributed around Earth worked in concert to produce the first image of a black hole. By coordinating their signals, they achieved clarity equivalent to a single dish larger than any human-made structure could actually be built on land. The first black hole photograph was released in 2019. This milestone required a telescope network essentially as large as our world.
The next frontier involves moving these networks beyond our atmosphere. Physicist Alex Lupsasca and his team are planning the Black Hole Explorer (BHEX). This mission aims to place a space-based dish 20,000 kilometres from Earth to extend the EHT network. By creating a receiver effectively larger than the planet, researchers hope to capture high-precision data on 'photon rings'—mysterious features of supermassive black holes like M87*. Lupsasca is the deputy project scientist for this mission. He specializes in studying physics within extreme environments like black hole centers.
This leap in scale is driven by the desire to test the limits of physics. By observing these extreme environments with unprecedented clarity, scientists aim to potentially break Albert Einstein’s theory of gravity and uncover the fundamental structure of reality. The BHEX goal is to spot parts of black holes never seen before. Such data might reveal entirely new physical laws.
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Sources
- Summary by Intellect · source: How Can You Build A Telescope As Large As The Earth
- Also: The physicist who wants to build a telescope bigger than Earth | New Scientist
- Also: www.scientificamerican.com — How to Build an 80-Foot-Wide Telescope Mirror to See Deep Space
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