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Glossary · Telescopes & Instruments
Interferometry
Combining separate telescopes so they resolve detail like one enormous dish.
Resolution depends on aperture, and there is a practical limit to how big a single mirror or dish can be. Interferometry gets round it by combining the signals from telescopes far apart: the resolution then depends on the distance between them rather than on their size. ALMA does this with 66 dishes across a Chilean plateau. Very Long Baseline Interferometry does it with telescopes on different continents, recording precisely timestamped data to be combined later — which is how the Event Horizon Telescope achieved an effective aperture the size of the Earth, and enough resolution to see a black hole's shadow in a galaxy 55 million light years away.
Where it has come up lately
Related terms
Lagrange point
Five places where two bodies' gravity lets a third sit still relative to both.
Adaptive optics
Bending a mirror hundreds of times a second to cancel out the atmosphere.
First light
The night a new telescope is pointed at the sky and actually works.
Seeing
How much the atmosphere is blurring the stars tonight, measured in arcseconds.
Questions
What is Interferometry?
Combining separate telescopes so they resolve detail like one enormous dish.
Why does it matter?
ALMA does this with 66 dishes across a Chilean plateau. Very Long Baseline Interferometry does it with telescopes on different continents, recording precisely timestamped data to be combined later — which is how the Event Horizon Telescope achieved an effective aperture the size of the Earth, and enough resolution to see a black hole's shadow in a galaxy 55 million light years away.