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Fast Facts
Hubble Ultra Deep Field

Hubble Ultra Deep Field (HUDF)


The HUDF is the deepest visible-light image of the universe ever observed by a telescope. The image shows about 10,000 galaxies, and is like a geologic core sample of the universe, cutting across billions of light-years of space. Hubble took 800 exposures in 400 orbits to build this image.


The most distant galaxies in the HUDF are seen as they were 13 billion years ago, when the universe was only 5 percent of its present age. These observations approach the time in the early universe when stars first began to shine.


The HUDF is found in the constellation Fornax, located in the Southern Hemisphere. This region of the sky is so empty that only a handful of the stars within our Milky Way Galaxy can be seen in the image.

Distance from Earth

The distances of the galaxies in the HUDF vary. The nearest, larger, brighter, well-defined spiral and elliptical galaxies are about a billion light-years away. The farthest, smallest, reddest galaxies, numbering about 100, are 13 billion light-years away and may be among the most distant known.


The patch of sky is less than 2 percent of the area of the full Moon as seen from Earth. The HUDF measures only one-seventeenth of a degree across, an angular size smaller than that of the largest impact basin on the Moon.

About 10,000 galaxies, some as far as 13 billion light-years away, range over this tiny section of sky.

Enlarge Image


"Fast Facts: Hubble Ultra Deep Field" is a table that lists the name, description, location, size, and distance of the HUDF from Earth. A picture of the field is included.

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Adaptable, at teacher's discretion
How to use in the classroom

Use this resource as:

A source of information. Read the table to find out about the HUDF.

A mapping activity. Locate the HUDF's associated constellation on a star map.

An inquiry tool. Have students write down questions they would like answered about the image and the information in the Fast Facts table.

An engagement tool. Involve students in a discussion.


Related materials

HubbleSite press release: "Hubble's Deepest View Ever of the Universe Unveils Earliest Galaxies"

Amazing Space resources by topic: Galaxies