The Farthest Visible Reaches of Space

About the Image

 

Current observations suggest that the Universe is about 13.7 billion years old. We know that light takes time to travel, so that if we observe an object that is 13 billion light years away, then that light has been traveling towards us for 13 billion years. Essentially, we are seeing that object as it appeared 13 billion years ago.

With every year that passes, our newest technology enables us to see further and further back.

Ultra Deep Field The image used for this stop on our journey is the Hubble Ultra Deep Field (UDF).
The UDF is the deepest view of the visible universe to date (it was created in 2003-2004). There are approximately 10,000 galaxies in this view, which is a sort of "core sample" of a very narrow patch of sky near the constellation Fornax. The smallest, reddest galaxies in the image, of which there are about 100, may be among the most distant known objects! Ultra Deep Field Location

When we look at these objects, we are looking back in time nearly 13 billion years, to when the Universe was only 800 million years old, and galaxies were first forming (as shown in the diagram below). For more information on the UDF, try this press release .

HST views the universe

Image Credits: UDF - NASA/ESA/S. Beckwith(STScI) and The HUDF Team.
For UDF Location and Age of the Universe graphics: NASA

What is the Farthest Known Object From Earth?

The objects in the Hubble Ultra Deep Field may well be the farthest known objects, but there are other contenders.

They include a galaxy called Abell 1835 IR1916, which was discovered in 2004, by astronomers from the European Southern Observatory using a near-infrared instrument on the Very Large Telescope. The object is visible to use because of gravitational lensing by the galaxy cluster Abell 1835, which is between this object and us. (Gravitational lensing can occur when a galaxy cluster is so massive and so compact that its gravity bends and focuses the light from galaxies that lie behind it, making it appear brighter than it would be without the lensing.) This galaxy is thought to be about 13.2 billion light years away, which means it would date to about 500 million years after the Big Bang. This find has not been verified by other instruments - the Spitzer Space Telescope tried in 2006 without success.

Abell Cluster

Also in 2004, a team using both the Hubble Space Telescope and the Keck Observatory discovered a galaxy that is believed to be about 13 billion years away from us. It was found when observing the galaxy cluster Abell 2218. The light from the distant galaxy was visible because of gravitational lensing. The very distant object is the one circled. For more information, check out this press release.

Image Credit: European Space Agency, NASA, J.-P. Kneib (Observatoire Midi-Pyrénées) and R. Ellis (Caltech)
Subaru Deep Field

In 2003, astronomers using the Subaru Deep Field, found a galaxy that is approximately 12.8 billion light years away. They hope to find more distant galaxies to give them an understanding of the early history of the Universe.

Image Credit: National Astronomical Observatory of Japan

Distance Information

Some of the most newly detected objects may be over 13 billion light years away, as derived from a standard model of the Universe. However, a powerful new generation of telescopes, like the James Webb Space Telescope, will be needed to confirm the suspected distances of these objects.

When 13 billion light years is translated into kilometers, there are a staggering number of zeros - it comes out to approximately 123,000,000,000,000,000,000,000 km.

As time progresses, so will our ability to see futher and further away - giving us insight on the very beginnings of the Universe's existence!

How do We Calculate Distances of This Magnitude?

At these distances, objects' redshifts are used, with and extension of Hubble's Law to the distant Universe. Here, we have to know the history of how rapidly the universe was expanding at each moment in time. This can be calculated from the amount of normal and dark matter and of dark energy. Try Prof. Wright's Javascript cosmology calculator at:
http://www.astro.ucla.edu/~wright/CosmoCalc.html

For more information on Hubble's Law, please read the section on finding distances to the Nearest Superclusters.

Why Are These Distances Important To Astronomers?

Scientists have estimated the age of the Universe to be 13.73 billion years old (with an uncertainty of about 120 million years). When we observe an object that is 13 billion light years away, we are essentially observing it as it was 13 billion years ago, when the Universe was young. Being able to see and thus hopefully understand the early Universe is important to understanding how it was formed. If we see back far enough, perhaps we will catch a glimpse of the first galaxies as they were just forming. Perhaps we will someday be able to see the first starts forming. Could we see even further back than that? Only time (and technology) will tell!

Travel Time

At the rate of 17.3 km/sec (the rate Voyager is traveling away from the Sun), it would take around 225,000,000,000,000 years to reach this distance. At the speed of light, it would take 13 billion years!

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