The sun, our closest star, offers astronomers a unique opportunity to study its surface in detail due to its proximity. Unlike the distant stars we see at night, the sun appears as a filled circle in the sky, allowing us to observe features such as sunspots, faculae, and granules. However, the stars in the night sky, including the nearest one to us, Proxima Centauri, are much farther away, making them appear as mere points of light through a telescope.
While it is technically possible to resolve other stars and study them in detail, the turbulent atmosphere poses a challenge by smearing out details of astronomical objects. Techniques such as adaptive optics and speckle imaging have been developed to overcome this limitation, providing sharp images of nearby large stars. However, the fundamental obstacle of aperture size defining a telescope’s resolution remains a challenge.
Interferometry, a technique that relies on the wave nature of light, offers a solution to this limitation. By combining the light from two telescopes separated by a distance, interference patterns can be analyzed to create detailed images of stars. This technique has been successfully implemented in radio observations and has been developed for optical wavelengths as well.
One of the largest telescopes in the world, the Very Large Telescope (VLT), utilizes interferometry with four 8.2-meter telescopes to achieve phenomenal resolution. The Center for High Angular Resolution Astronomy (CHARA) array goes even further with six one-meter telescopes separated by up to 330 meters, providing superhigh-resolution images of stars. These images have revealed surprising structures and behaviors in stars, such as bubbles of hot gas rising from their interiors and irregular changing shapes.
The resolution of optical interferometry is limited only by engineering capabilities and data processing speed, offering the potential for even larger virtual telescopes in the future. With advancing technology, astronomers may continue to uncover new insights and discoveries by studying the faces of far more stars, much like we have learned from studying our own sun.
