Hubble Deep Field - revealing the universe
In December 1995 the Hubble Space Telescope took a long exposure image of the sky, where only a very few stars had been noticed before, and practically was an unknown side of the sky. However, astronomers and astrophysicists had always been concerned if anything existed there. After having constructed the image known as the Hubble Deep Field (HDF), they were also surprised by what they had seen! (The image can be seen by positioning the mouse on the picture!)
The area consists of a significant number of objects (approximately 3000), most of which are rising and emerging galaxies. It seems unbelievable but the photo shows that particular part of the universe from 12 billion years before!
The light, which the telescope collected during the long exposure, practically travelled 12 billion light-years (a light-year is the distance that light travels in a vacuum in one year - at the speed of light) from the object it was emitted from until it reached the telescope.
The image, which they managed to take by capturing this light, in fact looks back approximately 12 billion years. The image can also be considered a time travel, as we are able to see that far back in time (a part of the galaxies showed by the picture has already been destroyed!)
After nearly three years of the HDF in October 1998, another image was taken in another section of the sky in the constellation of Tucana near the South Pole. It was taken by the same technique, and became known as HDF-S (Hubble Deep Field - South). Revealing similar objects, the image underlies the principle that the universe shows similar strcture in all directions.