But now an worldwide team of astronomers has assembled a mosaic - a composite image - called the Hubble Legacy Field combining 7,500 separate exposures that captured around 265,000 galaxies over the last 16 years.
The most comprehensive image of galaxies is the result of the collective work of 31 teams working with Hubble. This solitary image entails the complete history of the development of galaxies in the universe for their era as infants to when they evolve into fully grown adults. In 1995, the Hubble Deep Field captured several thousand previously unseen galaxies.
You're looking at 265,000 individual galaxies that extend all the way back to just 500 million years after the Big Bang, when the universe was still young and Earth wasn't even a planet. "Such exquisite high-resolution measurements of the legacy field catalog of galaxies enable a wide swath of extragalactic study", says Whitaker, the catalog lead researcher. Frequently these types of surveys have engendered unexpected findings which have had a profound influence on our comprehension of galaxy evolution.
The subsequent Hubble Ultra Deep Field from 2004 revealed almost 10,000 galaxies in a single image.
The legacy field also uncovers a zoo of unusual objects.
Since then, astronauts have flown out to Hubble several times to make repairs, upgrade cameras, and install new hardware, improving the observatory's view of deep space. The mosaic of images seen here document 16 years of observations for the NASA/ESA Hubble Space Telescope.
The Hubble focuses on areas in deep outer space "where some of the most profound mysteries are still buried in the mists of time".
The Hubble observes ultraviolet wavelengths, which the atmosphere filters out, and it collects visible light. In the future, astronomers hope to broaden the multiwavelength range in the legacy images to include longer-wavelength infrared data and high-energy X-ray observations from two other NASA Great Observatories, the Spitzer Space Telescope and Chandra X-ray Observatory. They are the farthest out, and without a telescope, this is the best the human eye can do. "This will really set the stage for NASA's planned Wide Field Infrared Survey Telescope (WFIRST)", Illingworth said. In fact, this image from Hubble frames a ideal spiral specimen: the stunning NGC 2903. First discovered by the South Pole Telescope less than a decade ago, SPT-CL J0615-5746 is so massive that its gravity bends light like a lens, making it very useful for peering deep into the early Universe.