The Hubble Telescope Can See 13 Billion Light-Years Away

The ability of the Hubble Space Telescope (Deals) to capture images of the cosmos from such immense distances is akin to having a powerful time machine. Because light takes time to travel, when we observe a galaxy 13.4 billion light-years away, we are not seeing it as it is today, but as it was 13.4 billion years ago. This provides a remarkable snapshot of the "infant" universe, allowing astronomers to witness a period just 400 million years after the Big Bang. These early galaxies, like the one known as GN-z11, were much smaller and more compact than our modern Milky Way and were forming stars at a much more rapid rate. Observing them helps scientists piece together the story of how the first stars and galaxies came into existence.

To achieve these incredible feats, Hubble employs several clever techniques. For its famous "deep field" images, the telescope stares at a single, tiny, seemingly empty patch of sky for hundreds of hours. This extended exposure time allows the faint light from the most distant galaxies to accumulate on its sensors, revealing objects that would otherwise be invisible. Furthermore, as the universe expands, the light from these receding galaxies gets stretched into longer, redder wavelengths—a phenomenon called cosmological redshift. Hubble's sensitive instruments are designed to detect this stretched light, including in the near-infrared spectrum, giving it the capacity to see these ancient, faraway objects that are racing away from us.