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The Universe Within 14 Billion Light Years – NASA Atlas of the Universe – Note, this map only gives a rough cosmographical estimate of the expected distribution of superclusters within the observable universe; very little actual mapping has been done beyond a distance of one billion light-years.
The Andromeda Galaxy is approximately 2.5 million light-years away. 3 × 10 6 ly: The Triangulum Galaxy , at about 3 million light-years away, is the most distant object visible to the naked eye. 5.9 × 10 7 ly: The nearest large galaxy cluster, the Virgo Cluster, is about 59 million light-years away. 1.5 × 10 8 – 2.5 × 10 8 ly
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).
The particle horizon, also called the cosmological horizon, the comoving horizon, or the cosmic light horizon, is the maximum distance from which light from particles could have traveled to the observer in the age of the universe. It represents the boundary between the observable and the unobservable regions of the universe, so its distance at ...
For example, galaxies that are farther than the Hubble radius, approximately 4.5 gigaparsecs or 14.7 billion light-years, away from us have a recession speed that is faster than the speed of light. Visibility of these objects depends on the exact expansion history of the universe. Light that is emitted today from galaxies beyond the more ...
A light-year is the distance light travels in one Julian year, around 9461 billion kilometres, 5879 billion miles, or 0.3066 parsecs. In round figures, a light year is nearly 10 trillion kilometres or nearly 6 trillion miles. Proxima Centauri, the closest star to Earth after the Sun, is around 4.2 light-years away. [89]
Light from the initial flash arrives at the viewer first, while light reflected from dust or other objects between the source and the viewer begins to arrive shortly afterward. Because this light has only travelled forward as well as away from the star, it produces the illusion of an echo expanding faster than the speed of light. [3]
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 ...