We have some incredibly powerful telescopes that have given us spectacular views of the cosmos and allowed us to look back to the earliest days of the universe. These observatories, such as the James Webb Space Telescope (JWST), are astonishing feats of engineering that have required billions of dollars and decades of work.
But what if we could get our hands on an even better telescope that already exists? It wouldn't be a typical telescope. It wouldn't even come with a lens. But it would be by far the most powerful telescope we've ever built.
This telescope would use the sun itself.
To give you an idea of how powerful a solar telescope could be, consider the JWST. With a mirror 6.5 meters in diameter, the JWST is capable of a resolution of about one-tenth of an arcsecond, which is about 600 times better than that of the human eye. With that resolution, the telescope could see the details on a coin placed 40 kilometers away or pick up the pattern on a regulation football placed 550 kilometers away.
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Another example is the Event Horizon Telescopewhich is actually a network of individual instruments spread across the globe. By carefully coordinating its elements, the telescope has provided us with Awesome images of the gas disks surrounding giant black holesTo achieve this, it achieved an impressive resolution of 20 microarcseconds. With that resolution, the telescope could detect an orange resting on the surface of the moon.
But what if we wanted to go further? A larger telescope would need gigantic dishes or arrays of antennas flying across the solar systemand both would require enormous advances in our technological capabilities.
Fortunately, it turns out that there is already a giant telescope available, located right in the center of the solar system: the sun.
While the sun may not look like a traditional lens or mirror, it has a lot of mass. And in Einstein's Theory of general relativitymassive objects bend space.time around it. All light that touches the surface of the sun is bent and, instead of continuing in a straight line, it heads toward a focal point, along with all the other light that touches the sun at the same time.
Astronomers already use this effect, called gravitational lensto study the most distant galaxies in The universeWhen the light from these galaxies passes close to a giant galaxy cluster, the mass of that cluster amplifies and magnifies the background image, allowing us to see much farther than we normally could.
Solar gravitational lensing allows for almost unbelievable resolution. It is as if we had a telescope that reflected the width of the entire sun. An instrument placed at the right focal point would be able to take advantage of the gravitational deformation of sunlight. gravity to allow us to observe the distant universe with an astonishing resolution of 10^-10 arcseconds. That's about a million times more powerful than the Event Horizon Telescope.
Of course, there are challenges in using the solar gravitational lens as a natural telescope. The focal point of all this bending of light is 542 times larger than the Sun. distance between the Earth and the SunIt is 11 times more distance to plutoand three times the distance reached by humanity's most distant spacecraft, Traveler 1which was launched in 1977.
So not only would we have to send a spacecraft farther than ever before, it would also have to have enough fuel to stay there and move around. The images created by the solar gravitational lens would extend over tens of kilometers. spaceso the spacecraft would have to scan the entire field to build a complete mosaic image.
Plans to take advantage of solar lensing date back to the 1970s. More recently, astronomers have proposed developing a fleet of small, lightweight cubesats that would deploy solar sails to accelerate them to 542 AU. Once there, they would slow down and coordinate their maneuvers, creating an image and sending the data back to Earth for processing.
As far-fetched as this concept may seem, it's not far from reality. And what would we get with such a supertelescope? If it were pointed at Proxima b, the nearest known exoplanet, for example, it would offer a resolution of 1 kilometer. Considering that plans for JWST's successors hope to achieve exoplanet imaging capabilities where the entire planet is contained in a handful of pixels, the solar gravitational lens puts such ideas to shame; it's capable of offering an exquisite portrait of the detailed surface features of any exoplanet within 100 light-years, not to mention all the other astronomical observations it could achieve.
To say that this would be better than any known telescope is an understatement. It would be better than any telescope we could possibly build in any possible future for the next few hundred years. The telescope already exists, we just need to get a camera in the right position.