Astronomers with the Event Horizon Telescope have developed a new way to observe the radio sky with several frequencies, and we will soon be able to capture color images of super -massive black holes.
Color is an interesting thing. In physics we can say that the light color is defined by its frequency or wavelength. The longer the wavelength or the lower the frequency, the more it is in the direction of the red end of the spectrum light. Move towards the blue end, and the wavelengths are getting shorter and the frequencies are higher. Every frequency or wavelength has its own unique color.
Of course we don't see it that way. Our eyes see color with three different types of cones in our retina, which are sensitive to red, green and blue light frequencies. Our thoughts then use this data to create a color image. Digital cameras work similarly. They have sensors that grasp red, green and blue light. Your computer screen then uses red, green and blue pixels, making our brain seeing a color image.
Although we cannot see funking, radio telescopes can see colors that are referred to as bands. A detector can capture a narrow frequency range, which is referred to as a frequency band and resembles the way optical detectors capture colors. By observing the radio sky in various frequency straps, astronomers can create a “color” feature.
But that's not without problems. Most radio telescopes can only watch one band. Therefore, astronomers have to observe an object several times on different ribbons to create a color image. For many objects, this is perfectly fine, but it does not work. The picture can change so quickly that you cannot shy pictures. Imagine your telephone camera took a tenth of a second to capture every color of a picture. It would be okay for a landscape photo or a selfie, but the different pictures would not be aligned for an action.
This new method comes into play here. The team used a method called frequency phase transmission (FPT) to overcome the atmospheric distortions of funking light. By observing the radio sky with the 3 -mm wavelength, the team can track how the atmosphere distorts the light. This is similar to how optical telescopes use a laser to pursue atmospheric changes. The team showed how they can observe the sky at the same time with a 3 mm and a 1mm wavelength and corrected and sharpened the image collected by the 1 -mm wavelength. By correcting the atmospheric distortion in this way, radio astronomers could take consecutive images in different radio bands and then correct them all in order to create a high -resolution color image.
This method is still in the early stages, and this latest study is just a demonstration of technology. But it proves that the method can work. Future projects such as the EBT (NGETT) and the Black Hole Explorer (BHEX) can therefore build on this method. And that means that we will be able to live black holes and have in color.
Reference: Issaoun, Sara et al. “First frequency phase transmission of 3 mm onto the 1 mm band on a size.” The Astronomical Journal 169.4 (2025): 229.
