Cosmology

Deep Field1	This image, called the Hubble Deep Field (HDF), was assembled from 342 separate exposures taken with the Wide Field and Planetary Camera 2 (WFPC2) for ten consecutive days between December 18 and 28, 1995. Representing a narrow "keyhole" view stretching to the visible horizon of the universe, the HDF image covers a speck of the sky only about the width of a dime located 75 feet away. Though the field is a very small sample of the heavens, it is considered representative of the typical distribution of galaxies in space because the universe, statistically, looks largely the same in all directions. Gazing into this small field, Hubble uncovered a bewildering assortment of at least 1,500 galaxies at various stages of evolution. Most of the galaxies are so faint (nearly 30th magnitude or about four-billion times fainter than can be seen by the human eye) they have never before been seen by even the largest telescopes. Some fraction of the galaxies in this menagerie probably date back to nearly the beginning of the universe. The term "deep" in an astronomical sense means looking at the faintest objects in the universe. Because the most distant objects are also among the dimmest, the image is the equivalent of using a "time machine" to look into the past to witness the early formation of galaxies, perhaps less than one billion years after the universe's birth in the Big Bang. Essentially a narrow, deep "core sample" of sky, the HDF is analogous to a geologic core sample of the Earth's crust. Just as a terrestrial core sample is a history of events which took place as Earth's surface evolved, the HDF image contains information about the universe at many different stages in time.
Deep Field2	This is a magnified version of the Hubble Deep Field. Nearly a year of preparation preceded the observation. The HDF team selected a piece of sky near the handle of the Big Dipper (part of the northern circumpolar constellation Ursa Major, the Great Bear). The field is far from the plane of our Galaxy and so is "uncluttered" of nearby objects, such as foreground stars. The field provides a "peephole" out of the galaxy that allows for a clear view all the way to the horizon of the universe. Here's a movie showing a "zoom-in" to the location of the deep field image. Test exposures made in early 1995 with Hubble and the 4-meter telescope at Kitt Peak National Observatory also confirmed the field is devoid of large galaxy clusters, which would interfere with seeing farther and fainter objects. The target field is, by necessity, in the continuous viewing zone (CVZ) of Hubble's orbit, a special region where Hubble can view the sky without being blocked by Earth or interference from the Sun or Moon. Staring at one spot in the sky for ten days, Hubble kept taking pictures one after another for the entire exposure time, accumulating data. Each exposure was typically 15 to 40 minutes long. Separate images were taken in ultraviolet, blue, red, and infrared light. By combining these separate images into a single color picture, astronomers will be able to infer -- at least statistically -- the distances, ages, and composition of the galaxies in the HDF image. Astronomers at ST ScI processed the frames, removing cosmic rays and other artifacts, and put them together into one final picture. Each time they add a picture, the view got deeper, revealing fainter objects. When they were done they had the deepest picture ever taken of the heavens.
Deep Field3	This is a greatly magnified version of the Hubble Deep Field.
Deep Field4	Hubble Deep Field in the southern sky in the constellation Tucana.
UltraDeepField	The deepest deep field ever! The Hubble telescope took the equivalent of a 3-month long(!) exposure of a small area of sky in the constellation Fornax which is 4 times as sensitive as the original Hubble deep field. This image contains about 10,000 galaxies in an area about one tenth the area of the full moon. Some of the galaxies are thought to have existed only 400 to 800 million years after the big bang at red shift factors of 7 to 12.
GalaxyBirth	The most ancient galaxies identified in the Hubble Ultra Deep Field.
Human Search	A picture illustrating the human desire to understand what is behind the appearance of the universe.
Galaxy Distribution	A 3D map of the distribution of about 2,000 galaxies.
Expansion	Animation showing the expansion of a closed universe.
Blackbody	The blackbody spectrum of the cosmic background radiation.
Background Radiation	All-sky maps of the anisotropy in the cosmic background radiation.
Cosmic Lookback	An illustration of looking back in time to see the evolution of the universe.
Hubble Diagrams	Graphs of recession velocity vs. distance.
Cosmic Composition	An illustration of the composition of the universe.