Now that we’ve seen our first one, we want more, and we want them better. Here’s how to get there.
To resolve any astronomical object, you must achieve resolutions superior to the apparent size of your target.
The largest black holes, as viewed from Earth, possess event horizons merely tens of microarcseconds (μas) in angular size.
A telescope’s resolution, meanwhile, is fundamentally determined by how many wavelengths of light fit across its physical diameter.
We can surpass that limit by leveraging an array of telescopes, using the technique of very-long-baseline interferometry.
By properly equipping and calibrating each participating telescope, the resolution sharpens, replacing an individual telescope’s diameter with the array’s maximum separation distance.
At the Event Horizon Telescope’s maximum baseline and wavelength capabilities, it will attain resolutions of ~15 μas: a 33% improvement over the first observations.
Currently limited to 345 GHz, we could strive for higher radio frequencies like 1-to-1.6 THz, progressing our resolution to just ~3-to-5 μas.
But the greatest enhancement would come from extending our radio telescope array into space.
Outfitting them with atomic clocks and rapid data downlinks could extend our baseline to the size of the Moon’s orbit.
With both frequency and baseline improvements, we could reach ~0.05 μas resolution: 440 times sharper than our first event horizon image.
Mostly Mute Monday tells a scientific story in images, visuals, and no more than 200 words. Talk less; smile more.Ethan Siegel is the author of Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.