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So if the matter that originally emitted the oldest CMBR photons has a present distance of 46 billion light-years, then the distance would have been only about 42 million light-years at the time of decoupling. The light-travel distance to the edge of the observable universe is the age of the universe times the speed of light, 13.8 billion light ...
Visible-light astronomy has existed as long as people have been looking up at the night sky, although it has since improved in its observational capabilities since the invention of the telescope, which is commonly credited to Hans Lippershey, a German-Dutch spectacle-maker, [1] although Galileo played a large role in the development and ...
The human eye discards what it sees from split-second to split-second, but photographic film gathers more and more light for as long as the shutter is open. The resulting image is permanent, so many astronomers can use the same data. It is possible to see objects as they change over time (SN 1987A is a spectacular example).
As an example, the Milky Way is roughly 100,000–180,000 light-years in diameter, [54] [55] and the nearest sister galaxy to the Milky Way, the Andromeda Galaxy, is located roughly 2.5 million light-years away. [56] Because humans cannot observe space beyond the edge of the observable universe, it is unknown whether the size of the universe in ...
The spherical volume of space that will become the observable universe is 42 million light-years in radius at this time. The baryonic matter density at this time is about 500 million hydrogen and helium atoms per m 3, approximately a billion times higher than today. This density corresponds to pressure on the order of 10 −17 atm. Dark Ages
The object's name is derived from its location in the GOODS-North field of galaxies and its high cosmological redshift number (GN + z11). [12] It is observed as it existed 13.4 billion years ago, just 400 million years after the Big Bang ; [ 4 ] [ 13 ] [ 14 ] as a result, its distance is sometimes inappropriately [ 15 ] reported as 13.4 billion ...
The light-month, roughly one-twelfth of a light-year, is also used occasionally for approximate measures. [37] [38] The Hayden Planetarium specifies the light month more precisely as 30 days of light travel time. [39] Light travels approximately one foot in a nanosecond; the term "light-foot" is sometimes used as an informal measure of time. [40]
Light curve of NGC 2525 after a supernova. Time-domain astronomy is the study of how astronomical objects change with time. Said to have begun with Galileo's Letters on Sunspots, the field has now naturally expanded to encompass variable objects beyond the Solar System. Temporal variation may originate from movement of the source, or changes in ...