Typically, they have a mass of about one million billion times the mass of the Sun and form over billions of years as smaller groups of galaxies slowly come together.
After that first image, Hubble started visiting a different patch of space over and over with multiple different surveys, including the Ultra and eXtreme Deep Fields. The wavelength range stretches from ultraviolet to near-infrared light, capturing the key features of galaxy assembly over time.
"Just as ancient paintings can tell us about the period of history in which they were painted, so too can ancient galaxies tell us about the era of the Universe in which they existed", Hubble astronomers said.
This is a portion of the Hubble Legacy Field, which combines thousands of images and represents 16 years' worth of Hubble observations. With that being said, astronomers can use the potential of this image to get a closer look at what we know as the expansion of the Universe.
After its launch into low Earth orbit in 1990, astronomers debated whether it was worth sending the Hubble Space Telescope on a "fishing expedition" to take a very long exposure of a small, seemingly blank piece of sky. "We've put together this mosaic as a tool to be used by us and by other astronomers", Illingworth added. "Often, these kinds of surveys have yielded unanticipated discoveries which have had the greatest impact in our understanding of galaxy evolution".
The Hubble telescope has captured a dazzling new photograph of a spiral galaxy, NGC 2903. Ground-based observations were unable to establish how galaxies formed and evolved in the early Universe.
Dotted across the sky in the constellation of Pictor (The Painter's Easel) is the galaxy cluster highlighted here by the NASA/ESA Hubble Space Telescope: SPT-CL J0615-5746, or SPT0615 for short.
The team also says that galaxies show when the chemical elements originated and enabled the conditions that could support life.
The field of view is just roughly the size of a full moon in the sky.
"To learn about cosmological history, we explore the most distant reaches of the Universe, probing ever further out into the cosmos".
The new mosaic captures roughly 30 times as many galaxies as any previous deep-field view and spans nearly the width of the full moon, according to the NASA statement.
The new mosaic is one of the widest views ever taken of the universe, stretching nearly the width of the full moon in Earth's sky. By comparison, the XDF survey, which focuses on the same region of the sky, covers an area of space less than one-tenth of the moon's diameter.
Not all of the Legacy Field is created equal.
Assembling all of the observations was an vast task.
The image is the end result of a project to combine data from 31 Hubble programs carried out by different teams of astronomers.
The Hubble focuses on areas in deep outer space "where some of the most profound mysteries are still buried in the mists of time".