The conventional wisdom is that if you want to look at more distant objects in the universe, you need a bigger telescope. What if you didn’t have to build one, though? A new analysis claims it may be possible to use the Earth’s atmosphere as a giant lens to observe far-away stars and galaxies on the cheap. The process may even work in reverse to send signals to distant locales.
Earth’s atmosphere has traditionally been seen as an impediment to astronomy. The thick envelope of gas that keeps us alive also obscures space. That’s why the most powerful telescopes are the ones we launch into orbit like Hubble and the upcoming James Webb Space Telescope. And then there are massive ground-based telescopes like the 25-meter Giant Magellan Telescope under construction in Chile.
These projects are expensive and deviously complex. The Giant Magellan Telescope will cost around $1 billion, and the Webb Telescope is closing in on $10 billion after years of delays. The “terrascope” proposed by Columbia University astronomer David Kipping could be vastly easier. Using the Earth’s atmosphere as a lens to focus light has been proposed in the past, but Kipping’s new calculations demonstrate how powerful such a setup could be.
As light from distant objects passes through Earth’s atmosphere, some of it passes through the upper atmosphere and refracts into a cone-like shape. If you were to place a small satellite in orbit around the moon, it could use a small mirror to collect that light, essentially magnifying distant objects. According to Kipping, a 1-meter terrascope could potentially amplify light by 22,500 times. That’s far, far beyond the capabilities of any telescope we could manufacture with current technology.
Kipping also points out you could equip a terrascope with a radio transmitter rather than a mirror. By bouncing signals off the Earth’s atmosphere, you could potentially improve communication with other planets in the solar system. Some of them have atmospheres, so you could bounce the signal onward creating an “Internet across the solar system.”
That all sounds great, but there are a few potential pitfalls. For one, you can’t point the terrascope anyplace you like. Your lens is the Earth itself, so you can only spy on things that are behind the planet. That’s just a tiny fraction of the sky. Kipping’s calculations also use simplified atmospheric models that don’t take into account conditions like high-altitude clouds. Light contamination from Earth could also make terrascope signals too noisy to be useful. Kipping agrees there’s a lot of work to be done, but it’s a fascinating idea.
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