There may not be a more humbling experience than looking at Earth's place in the Galaxy in relation to other heavenly bodies in Ultra Deep Field.
Hubble scientists attempted to accomplish something extraordinary in 1996, so they trained the Hubble telescope on a part of the sky that appeared absolutely empty. A patch no bigger than a grain of sand, held out at arm's length and devoid of any planet, stars or galaxies. The area was close to the familiar constellation, the Big Dipper.
Hubble, a space telescope launched in April 1990, has been orbiting the earth ever since. Its unparalleled advantage lies in the fact that it is stationed outside of Earth's atmosphere, thus giving it a clear view of space.
It was somewhat a risky undertaking by the astronomers, considering that observation time on this telescope is in very high demand and some questioned whether it would be wasted looking at mere darkness. Others feared that the images thus collected would be as black as the space at which it was being pointed.
Nonetheless, they opened the telescope and slowly over the course of a complete ten days, photons that have been travelling for almost thirteen and half billion years finally ended their journey on the detector of humankind’s most powerful telescope, their flimsy signals collected almost one by one.
When the telescope was finally closed and the images were processed, the light from over 3,000 galaxies had covered the detector producing one of the most profound and awesome images in all of human history. Every single smear, spot and dot was an entire galaxy and each one contains hundreds of billions of stars.
Telescope Pointed at Empty Patch of Sky Near Orion
Later, in 2004 the astronomers did it again, refitting the telescope with detectors with increased sensitivity and filters that allowed in more light than ever before. This time, they pointed the telescope toward an area near the constellation Orion. They opened the shutter for over eleven days and four hundred complete orbits around the earth.
Over ten thousand galaxies appeared in what became known as the Ultra Deep Field - an image that represents the farthest sweep into the universe ever seen. The photons from these galaxies, according to the astronomers, left when the universe was only 500 million years old and 13 billion years later they ended their long journey as a small bleep on a telescope close-circuit display.
Observing the Red-shift of Galaxies in the Deep Field
These galaxies while appearing to stand still are racing away from the Milky Way, in some cases faster than the speed of light. The space-time between the Milky Way and everything else grows larger by the minute, pushing the galaxies to a distance of over 47 billion light years.
Also, because of universal expansion, the farther away something is from the Milky Way galaxy the more its light is shifted toward the red and the faster it appears to be moving. Edwin Hubble himself discovered this phenomenon by measuring the red-shift of many galaxies; and it is a measure of not only speed but distance as well.
Recently, astronomers have used the measured red shifts of the galaxies inside the image to make a 3-D model of the Ultra Deep Field. There are over 100 billion galaxies in the universe. This number does not really mean much without context, and one’s brains have no way of accurately putting this figure in any meaningful perspective.
When one looks at this image, however, and thinks about the context of how it was made, and really understands what it means, perspective is immediately possible, and one cannot help but be forever awed.
Astronomers pointed the most powerful telescope that was ever built by humans at absolutely nothing for no other reason except curiosity, only to discover that Earth, to use the words of the pre-eminent astronomer, Carl Sagan, is only "a mote of dust suspended in a sunbeam."
References:
“Space Telescope Science Institute Newsletter," Volume 19 Issue 03
Sagan, Carl. Pale Blue Dot: A vision of The Human Future in Space, Random House Inc., 1998
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