WHAT’S THE FARTHEST INTO SPACE WE’VE SEEN?

The most distant observed object is HD1, a galaxy candidate identified in April 2022. The light we’re seeing from this object has been travelling through the universe for about 13.5 billion years, yet we are seeing the object as it was when the light left it and began its journey to Earth. In the 13.5 billion years that the photons of light given off by HD1 have been travelling, that distance has stretched, giving a proper distance of approximately 33.4 billion light years. As a result, the light itself has become stretched, which causes it to be shifted more towards the red end of the spectrum, or redshifted. The farther you look out into space, the farther back in time you’ll see. This is because light has a finite speed of around 186,000 miles a second.

Although it travels extremely fast, it still takes time for light to travel across vast distances in the universe. Because of this, there’s a limit to what we can see. It also means there are regions of space we will never see because they are so far away – even though the light is travelling towards us, the space between us and the most distant objects is expanding faster.

We calculate the age of the universe to be around 13.8 billion years old, so we can only see light that has been travelling for this amount of time. However, the rate of expansion of the universe has been changing.