Deepest-ever view of the Universe
September 26, 2012
Astronomers have assembled a new, improved portrait of our deepest-ever view of the Universe called the eXtreme Deep Field, or XDF, by combining ten years of NASA/ESA Hubble Space Telescope observations taken of a patch of sky within the original Hubble Ultra Deep Field.
The XDF is a small fraction of the angular diameter of the full Moon — a small area of space in the constellation of Fornax (The Furnace), created using Hubble Space Telescope data from 2003 and 2004. By collecting faint light over one million seconds of observation, the resulting image revealed thousands of galaxies, both nearby and very distant, making it the deepest image of the Universe ever taken at that time.
5500 galaxies
The new full-color XDF image is even more sensitive than the original Hubble Ultra Deep Field image, thanks to the additional observations, and contains about 5500 galaxies, even within its smaller field of view. The faintest galaxies are one ten-billionth the brightness that the unaided human eye can see.
Magnificent spiral galaxies similar in shape to the Milky Way and its neighbour the Andromeda galaxy appear in this image, as do large, fuzzy red galaxies in which the formation of new stars has ceased. These red galaxies are the remnants of dramatic collisions between galaxies and are in their declining years as the stars within them age.
Peppered across the field are tiny, faint, and yet more distant galaxies that are like the seedlings from which today’s magnificent galaxies grew. The history of galaxies — from soon after the first galaxies were born to the great galaxies of today, like the Milky Way — is laid out in this one remarkable image.
Hubble pointed at a tiny patch of southern sky in repeat visits made over the past decade with a total exposure time of two million seconds. More than 2000 images of the same field were taken with Hubble’s two primary cameras: the Advanced Camera for Surveys and the Wide Field Camera 3, which extends Hubble’s vision into near-infrared light. These were then combined to form the XDF.
Looking back 13.2 billion years in time
“The XDF is the deepest image of the sky ever obtained and reveals the faintest and most distant galaxies ever seen. XDF allows us to explore further back in time than ever before,” said Garth Illingworth of the University of California at Santa Cruz, principal investigator of the Hubble Ultra Deep Field 2009 (HUDF09) program.
The Universe is 13.7 billion years old, and the XDF reveals galaxies that span back 13.2 billion years in time. Most of the galaxies in the XDF are seen when they were young, small, and growing, often violently as they collided and merged together. The early Universe was a time of dramatic birth for galaxies containing brilliant blue stars far brighter than our Sun. The light from those past events is just arriving at Earth now, and so the XDF is a time tunnel into the distant past when the Universe was just a fraction of its current age. The youngest galaxy found in the XDF existed just 450 million years after the Universe’s birth in the Big Bang.
Before Hubble was launched in 1990, astronomers were able to see galaxies up to about seven billion light-years away, half way back to the Big Bang. Observations with telescopes on the ground were not able to establish how galaxies formed and evolved in the early Universe.
Hubble gave astronomers their first view of the actual forms of galaxies when they were young. This provided compelling, direct visual evidence that the Universe is truly changing as it ages. Like watching individual frames of a motion picture, the Hubble deep surveys reveal the emergence of structure in the infant Universe and the subsequent dynamic stages of galaxy evolution.
The NASA/ESA/CSA James Webb Space Telescope (Webb telescope), scheduled for launch in 2018, will be aimed at the XDF, and will study it with its infrared vision. The Webb telescope will find even fainter galaxies that existed when the Universe was just a few hundred million years old. Because of the expansion of the Universe, light from the distant past is stretched into longer, infrared wavelengths. The Webb telescope’s infrared vision is ideally suited to push the XDF even deeper, into a time when the first stars and galaxies formed and filled the early “dark ages” of the Universe with light.
Comments (9)
by Antikytherapy
In the last sentence of the 8th paragraph, ” The youngest galaxy found in the XDF existed just 450 million years after the Universe’s birth in the Big Bang.”, should it read “oldest” instead of “youngest”?
by Editor
Youngest with reference to the big bang.
by travis
Could somenone explain how the the picture contains galaxies that are dying? This doesnt make sense to me.
by Mike
I imagine there must be a point that we can’t see past. Because nothing can travel faster than the speed of light, the universe cannot expand as fast as light is catching up. As all matter was closer together in a younger universe, it would have taken less time for light to reach the outer limits of the universe. So, we could never see the early universe because the light would have reached us long before now. I guess though, if we were looking at the other side of the center of the universe, and the galaxies were expanding in the opposite direction, then it would take considerably longer for the light to catch up. Still, there must be a limit to how far back we can see.
This brings me to a question for someone. If object A were traveling close to the speed of light relative to an origin, say the location of the big bang, can an object B move in the opposite direction close to the speed of light, thus object A relative to object B travel faster than the speed of light?
by Ted Rodosovich
a quikie reaction … how about the curvature of space as a consideration?
by Bri
Space itself is very flat. The effects of gravity are very close to the gravitational body. In other words, it affects space very close to it’s surface, and even then, only in very small amounts, relative to the size os a star. When the confirmed Einstein’s equations, it took several attempts and the amount of deviation is so small that they had to do pains taking measurement repeatedly.
by Carl Brooks
no, the speed of light is constant and cannot be overhauled (as far as we know). Object A would look upon object B and observe that its time is moving much slower than its own time, which seems to run at the normal rate. Object B would observe the exact same thing while observing object A. For a stationary observer looking at both objects, time appears to slow down for both object, while the observers time appears to stay at the normal rate. both objects looking upon the stationary observer would also see the observers time seem to slow down aswell.
The big bang happened everywhere in the universe. every point is the center. We are enveloped in an ever increasing sphere of how far back we can see. This is known as the visible universe. Beyond this point we cannot see because the light hasn’t reached us yet. You are right that there is a point at which the universal expansion rate makes it impossible for the light to ever catch us up. This is beyond the visible universe. i dont know however if the universe is old enough for this to have happened to the light from the big bang. Perhaps the Webb telescope will help answer these questions.
by Gorden Russell
Never mind. It came up first on search…Brian Aldiss.
by Gorden Russell
Who wrote, “Galaxies like grains of sand?”