How Taking Pictures of ‘Nothing’ Changed Astronomy

The world was left in awe by the release of the deepest image ever obtained by a telescope. There are a lot of different shapes and sizes of galaxies in the dark of the universe. The universe was a few hundred million years old. It's helpful to know how deep-field observations came to be, since we're so far away from the big bang.

The Hubble Space Telescope launched in the early 1990s, which is when the first deep field was created. The concept of deep-field observations was still new. astronomers would point the telescope to a source at a specific spot in the sky and expose orintegrate as needed. Astronomers would point the telescope to a sky region devoid of any visible source and use a very long exposure time to see as many faint sources of light as possible. Hubble was the best platform for deep-field images of our planet at the time.

The approach was not thought to be revolutionary. The Institute for Advanced Studies argued in 1990 that a deep-field image from Hubble wouldn't reveal as much as ground telescopes. Bahcall's solution to the problem of solar neutrinos and his calculations of the distribution of stars around a black hole were well known. The Hubble Space Telescope was the product of his contributions. He thought that the images from the Hubble deep field could support the study of the size and shape of faint galaxies and quasars.

It wasn't necessary to try deep-field images with Hubble. The first attempt did not happen until after the winter holidays of 1995. A small patch of the sky in the Ursa Major constellation is just one-thirteenth of the moon's diameter. After seeing the resulting image, they realized it was a Christmas gift for the ages. Hubble is able to see through the stars in the target region. The telescope saw a lot of different shapes and sizes, some of them as far away as 12 billion light years away. Hubble was looking at time, gathering starlight that had been emitted millions of years ago. The image was instantly recognizable.

Did the Deep Field North reveal the norm? Is it possible that the astronomer was lucky to have pointed the telescope towards a crowded universe? The Deep Field South was obtained by Hubble. The telescope pointed towards the southern hemisphere even though the exposure was the same. The new image showed that the universe contained more than previously thought. One of the first big data challenges astronomy faced was due to the Hubble deep fields, which contained over 10,000 galaxies.

The visible realm of the spectrum isn't the only realm where deep-field images can be found. The world was ready for the first high-energy deep field, obtained with the Chandra X-ray observatory, at the turn of the millennium. A piece of the sky in the Lockman Hole was used to get the Chandra Deep Field South. Hundreds of black holes, some very remote, would appear in an image not as visually spectacular as the Hubble photographs, but dense with science. The field was imaged again with Chandra and it was the deepest field ever obtained in x-ray. The Chandra Deep Field North was released in 2003 with a lot of data.

The Hubble Ultra Deep Field was released in 2006 with the addition of the advanced camera for surveys. The universe was less than a billion years old when this shot was taken. The history of galaxy formation was shown in unprecedented detail by the Ultra Deep Field.

The Ultra Deep Field can be seen in optical wavelength. The expansion of the universe stretches out the wavelengths of light traveling through enormous expanses of intergalactic space, so if a galaxy is too far out, its optical light is shifted outside the visible range. The camera was needed to see farther out. The Ultra Deep Field was obtained with the addition of the near-IR camera to Hubble. A deep field was released in the year 2019. These images are good places to look for galaxies.

The Frontier Fields campaign represented the cutting edge of deep-field imagery and a preview of the first deep image. Hubble was pointed towards six large concentrations of galaxies. The light from a background source can be amplified by the presence of a large density of mass along the line of sight. The clusters were used as a magnifying glass. The Frontier Fields images are adorned with strange arcs of light, representing the stretched and amplified images of background galaxies much more far away than the cluster and possibly too faint to be seen by Hubble. Some of the most distant galaxies were shown in these shots.

It has been almost 200 years since photography was first used to take pictures. Our knowledge of the universe is being changed by cameras aboard a space telescope one million miles away. The two events are linked by the same goal of getting a deeper understanding of nature by looking at what we can't see.

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