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Learning From Our Past
"That Pale Blue Dot..."
The Pale Blue Dot is a photograph of planet Earth taken on February 14, 1990, by the Voyager 1 space probe from a record distance of about 6 billion kilometers (3.7 billion miles, 40.5 AU), as part of that day's Family Portrait series of images of the Solar System. In the photograph, Earth's apparent size is less than a pixel; the planet appears as a tiny dot against the vastness of space, among bands of sunlight reflected by the camera.
Voyager 1, which had completed its primary mission and was leaving the Solar System, was commanded by NASA to turn its camera around and take one last photograph of Earth across a great expanse of space, at the request of astronomer and author Carl Sagan. The phrase "Pale Blue Dot" was coined by Sagan himself in his reflections on the photograph's significance, documented in his 1994 book Pale Blue Dot: A Vision of the Human Future in Space.
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Hubble Ultra Deep Field
Before we were humbled from images of the James Webb Space Telescope, The Hubble Ultra-Deep Field (HUDF) is an image of a small region of space in the constellation Fornax, containing an estimated 10,000 galaxies.
The original release was combined from Hubble Space Telescope data accumulated over a period from September 24, 2003, through to January 16, 2004. Looking back approximately 13 billion years (between 400 and 800 million years after the Big Bang) it has been used to search for galaxies that existed at that time. The HUDF image was taken in a section of the sky with a low density of bright stars in the near-field, allowing much better viewing of dimmer, more distant objects. In August and September 2009, the HUDF field was observed at longer wavelengths (1.0 to 1.6 µm) using the infrared channel of the recently attached Wide Field Camera 3 (WFC3) instrument. When combined with existing HUDF data, astronomers were able to identify a new list of potentially very distant galaxies.
Located southwest of Orion in the southern-hemisphere constellation Fornax, the rectangular image is 2.4 arcminutes to an edge, 3 or 3.4 arcminutes diagonally. This is approximately one tenth of the angular diameter of a full moon viewed from Earth (which is less than 34 arcminutes), smaller than 1 sq. mm piece of paper held at 1 meter away, and equal to roughly one twenty-six-millionth of the total area of the sky. The image is oriented so that the upper left corner points toward north (-46.4°) on the celestial sphere.
