20 years ago: Hubble Ultra-Deep Field began
In August 2003, the Hubble Space Telescope began the Hubble Ultra-Deep Field project, which ended 800 exposures later, on January 16, 2004. The images from this project resulted in the image below, containing over 10,000 galaxies. It was the furthest we'd seen until the James Webb Telescope began its mission more recently.
"This view of nearly 10,000 galaxies is called the Hubble Ultra Deep Field. The snapshot includes galaxies of various ages, sizes, shapes, and colours. The smallest, reddest galaxies, about 100, may be among the most distant known, existing when the universe was just 800 million years old. The nearest galaxies - the larger, brighter, well-defined spirals and ellipticals - thrived about 1 billion years ago, when the cosmos was 13 billion years old.
The image required 800 exposures taken over the course of 400 Hubble orbits around Earth. The total amount of exposure time was 11.3 days, taken between Sept. 24, 2003 and Jan. 16, 2004.
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