For 25 years, the Hubble Space Telescope has scanned the skies and sent us the most incredible images, so we thought we should bring you the Hubble most important image ever taken,
Hubble Space Telescope
The telescope has been a huge success and given us an insight into places billions of light years away and into events that happened billions of years ago. The places that Hubble has looked at will forever be beyond our reach, however there is one image that has done more than any other to demonstrate the scale, depth and beauty of the universe.
The image is known as the Hubble Ultra Deep Field, and the image was captured over a period of 11 days in 2003. During the period, Hubble focussed two of its cameras – the advanced camera for surveys (ACS) and Near Infrared Camera and Multiobject Spectrometre (NICMOS) – on a tiny piece of sky in the southern constellation of Fornax. This area of sky is so small that it would need 50 images of the size to get a full image of the Moon.
Black space in the sky
From the surface of the Earth, the space photographed is entirely black with almost no visible stars within it. By using Hubble’s million-second shutter speed, the equipment was able to capture images of unimaginably faint, distant objects in the darkness. The dimmest objects in the picture were formed by a single photon of light hitting the sensors on Hubble each minute. Almost every one of these points of light is a galaxy, each a region of hundreds of billions of stars, with over 10,000 of these galaxies being identified. If you extend the results over the entire sky it suggests there are over 100 billion galaxies in the observable universe that each contain 100s of billions of suns.
History of the Universe
There is something more impressive about this image than the pure scale that it demonstrates. The thousands of galaxies captured are all very different distances from the Earth, which makes the image 3D in a very real sense. However, the third dimension is not special but it is temporal. As we look at this Hubble image, we are looking back in time; deep time and time beyond our comprehension. Just as an ice core can lead us back through layer after layer of the Earths history, the Hubble Ultra Deep Field image takes us back through the history of the Universe.
The image presents galaxies that have various ages, sizes shapes and colours, which are all various distances from Earth. The nearest of these galaxies which appear larger and better defined have more well defined spiral and elliptical shapes and are only a billion light years away. Since they would have formed after the Big Bang, they are about 12 billion years old, however the big attraction is the small red, irregular looking galaxies.
Towards the beginning of time
These red galaxies amount to about 100 in total within the image and they are the most distant objects ever observed. Some of these galaxies are way over 12 billion light years from Earth which means the light reaching us has been travelling for almost the 13.75 billion years that the Universe has existed. The most distant galaxy in the Deep Field image was identified in 2010, and is over 13 billion light years away so we are observing something that happened just 600,000 years after the birth of the Universe.
It is hard to grasp these massive expanses of space and time. Consider the image above was created by a handful of photons of light. When these photons began their journey from hot, primordial stars, there was no Earth or Sun and only a chaotic embryonic mass of young stars that would one day turn into the Milky Way. When these tiny particles of light had completed two thirds of their journey to us a swirling cloud of interstellar dust collapsed to form the Solar System.