The Hubble Deep Field is an image of a small region in the constellation Ursa Major, constructed from a series of observations by the Hubble Space Telescope. It covers an area about 2. 6 arcminutes on a side, about one 24-millionth of the whole sky, which is equivalent in angular size to a tennis ball at a distance of 100 metres. The HDF has become a landmark image in the study of the early universe.
About Hubble Deep Field in brief
The Hubble Deep Field is an image of a small region in the constellation Ursa Major, constructed from a series of observations by the Hubble Space Telescope. It covers an area about 2. 6 arcminutes on a side, about one 24-millionth of the whole sky, which is equivalent in angular size to a tennis ball at a distance of 100 metres. The field is so small that only a few foreground stars in the Milky Way lie within it; thus, almost all of the 3,000 objects in the image are galaxies, some of which are among the youngest and most distant known. The HDF has become a landmark image in the study of the early universe. The HUDF image was at the time the most sensitive astronomical image ever made at visible wavelengths, and it remained so until the Hubble eXtreme Deep Field was released in 2012. The similarities between the two regions strengthened the belief that the universe is uniform over large scales and that the Earth occupies a typical region of the Universe. In 2004 a deeper image, known as the Hubble Ultra-Deep Field, was constructed from just a few months of light exposure. The image was taken by the Space Telescope’s Wide Field and Planetary Camera 2 over ten consecutive days between December 18 and 28, 1995. Up to 10% of the HST’s observation time is designated as Director’s Discretionary Time, and is typically awarded to astronomers who wish to study unexpected transient phenomena, such as supernovae. The target field had to avoid known bright sources of visible light, and infrared, ultraviolet and X-ray emissions, to facilitate later studies at many wavelengths of the field, and to be in a region with a low background infrared ‘cirrus’, diffuse infrared emission believed to be caused by warm dust grains in hydrogen gas.
It was decided that the target field should be in the ‘continuous viewing zones’ —the areas of the sky which are not occulted by the Earth or the moon during Hubble’s orbit. Twenty candidate fields were selected from which 20 follow-up observations were carried out by the Keck Observatory, Very Large Array and Kitt Peak National Observatory. The images were taken by all three telescopes within the constellation of Ursa major, within the northern hemisphere of the Earth, so that the northern-hemisphere observations could be carried out on the northern side of the moon. In the southern hemisphere, the observations were made by Keck telescopes as well as the Kitt Peak Observatory and the Very Large Peak Observatory on the eastern edge of the Moon. These images were used to show how the Earth’s position in the sky affects our view of the universe, and how the universe has evolved over billions of years. It is believed the Earth is in the so-called ‘Continuous View Zone’ and this is where we can see the most distant galaxies in the universe at their most recent stages of development. The Earth is also in the ‘Continuous viewing Zone’, which was chosen so that it can be seen from a distance as far away as the International Space Station.
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This page is based on the article Hubble Deep Field published in Wikipedia (as of Nov. 05, 2020) and was automatically summarized using artificial intelligence.
