Hubble Deep Field

In 1990 NASA launched a telescope named after astronomer Edwin Hubble. The Hubble Space Telescope was a giant leap for the “world” of astronomy. It was one of the largest ever created and designed to be upgradable and maintained by astronauts. Since the telescope is in orbit, it is not disrupted by light pollution from Earth or its atmosphere.

As we near the 30-year anniversary of the instrument, it is hard to imagine the state of exploration of the universe without the Hubble. It has contributed to many scientific discoveries about planets, galaxies, and the universe itself, but for the first three years of its operation, it was nearly deemed a complete bust. The original 2.4-meter (7.9 feet) mirror was flawed, resulting in blurry images. What good is a telescope that returns fuzzy photos? Thanks to the design, however, astronauts were able to correct the issue. In 1993, the telescope started transmitting some of the clearest, most beautiful images of our universe ever seen.

Hubble Space Telescope viewed from Space Shuttle Atlantis - NASA

In most instances with a telescope, you point at a known entity. Take the location of the object and aim there. But what would happen if you zeroed in on a seemingly blank patch of sky? Would it just be empty space? In December 1995 NASA decided to find out. For 10 days they pointed Hubble at a patch of darkness “above” the Big Dipper in the constellation Ursa Major. The result is called the Hubble Deep Field.

When you view the image it is incomprehensively incredible to understand the size of the night sky you are observing. The photo covers an area of 2.6 arcminutes, which is about one 24-millionth of the whole sky. According to Robert Williams, the scientist in charge of Hubble’s direction at the time, it is the equivalent of the area covered by a pinhead at arm’s length. So how many space objects can be in a dark patch of sky the size of a pinhead?

Over 3,000!

This number is already impressive, but the kicker here is that nearly all the objects are not stars, but entire galaxies. Other than a few foreground stars, every piece of light you see in the following image is a galaxy of millions of individual stars:

The original Hubble Deep Field image; Credit: R. Williams/Hubble Deep Field Team/NASA/ESA

It’s easy to imagine the bigger clusters in that image as galaxies, but even the smallest dots are entire clumps of suns.

The image was a watershed moment for the study of the early universe. Some objects in the likeness are over 12 billion years old (the image, as in all photography, is a flattened, two-dimensional image of three-dimensional, physical space; some objects are closer/newer than others). Data collected from the process have aided in studies of the age of the universe, the creation of stars, the formation of galaxies, expansion of the universe, and dark matter.

Since then scientists have repeated and refined the practice of photographic deep fields. The original was taken in the northern celestial hemisphere. In 1998 they repeated the process in the opposite hemisphere, capturing the Hubble Deep Field South . 10 more days of light capture yielded a sister pic:

Hubble Deep Field South - photo from

Between 2003 and 2004, NASA aimed Hubble at the constellation Fornax to produce the next generation of deep photography, creating the Hubble Ultra-Deep Field. This region of space contains an estimated 10,000 galaxies. Over the next decade, scientists honed the Ultra-Deep Field, creating the eXtreme Deep Field. In 2019 a research institute in the Canary Islands released an even deeper version, called ABYSS Hubble Ultra Deep Field

The Ultra-Deep Field and its filtrations are the deepest images of the universe ever taken. Some objects in the image are over 13 billion years old, theorized to have existed between just 400 and 800 million years after the Big Bang.

Pondering the size of the cosmos is a sobering exercise. Our planet seems unfathomably large, but we start to become extraordinarily tiny at astronomical scales quickly. Other planets in our solar system dwarf us. All the planets are easily eclipsed by the sun. The solar system itself is so big it took Voyager 1 36 years to exit it at 38,000 miles per hour. This single solar system is one of 200 to 400 billion in our galaxy. Our galaxy, if viewed from the other side of the universe in a deep field image, might appear faintly as one dot on that picture. That picture is the equivalent of one pinhead of the entire sky. The Hubble Deep Field holds multitudes, but it is but a mere speck in the multitude of multitudes.

Our view of these immensities will most likely continue to sharpen, but the first image of a deep field will serve as an important benchmark for our ability to see just how grand the observable universe is.

Hubble Ultra-Deep Field
ABYSS Hubble Ultra Deep Field
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2 thoughts on “Hubble Deep Field”

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