* 1990 – STS-31: The Hubble Space Telescope is launched from the Space Shuttle Discovery.

This fact is now known as Hubble's law, though the numerical factor Hubble found relating recessional velocity and distance was off by a factor of ten, due to not knowing at the time about different types of Cepheid variables.

As a rule of thumb, a scattering or a decay process is cosmologically important in a certain cosmological epoch if the time scale describing that process is smaller or comparable to the time scale of the expansion of the universe, which is with being the Hubble constant at that time.

Edwin Powell Hubble ( November 20, 1889 – September 28, 1953 ) was an American astronomer who played a crucial role in establishing the field of extragalactic astronomy and is generally regarded as one the most important observational cosmologists of the 20th century.

The Hubble Ultra Deep Field is located within Fornax, and the Fornax Cluster, a small cluster of galaxies, lies primarily within Fornax.

* 1997 – Space Shuttle Discovery is launched on a mission to service the Hubble Space Telescope.

A new theory has been proposed that Modifies inertia by assuming it is due to Unruh radiation subject to a Hubble scale Casimir effect ( MiHsC, or quantised inertia ).

By 1929, however, the work of Hubble and others had shown that our universe is expanding.

In 1936 Hubble produced a classification system for galaxies that is used to this day, the Hubble sequence.

A slightly more extensive description of galaxy types based on their appearance is given by the Hubble sequence.

Since the Hubble sequence is entirely based upon visual morphological type, it may miss certain important characteristics of galaxies such as star formation rate ( in starburst galaxies ) and activity in the core ( in active galaxies ).

The Hubble classification system rates elliptical galaxies on the basis of their ellipticity, ranging from E0, being nearly spherical, up to E7, which is highly elongated.

* 1949 – The Hale telescope at Palomar Observatory sees first light under the direction of Edwin Hubble, becoming the largest aperture optical telescope ( until BTA-6 is built in 1976 ).

A generic prediction of chaotic inflation is an infinite ergodic universe, which, being infinite, must contain Hubble volumes realizing all initial conditions.

This follows directly from the cosmological principle, wherein it is assumed our Hubble volume is not special or unique.

* 2001 – A hydrogen atmosphere is discovered on the extrasolar planet Osiris by the Hubble Space Telescope, the first atmosphere detected on an extrasolar planet.

File: Lemaitre. jpg | Georges Lemaître ( 1894-1966 ): first person to propose the theory of the expansion of the Universe, first to derive what is now known as Hubble's law, made the first estimation of what is now called the Hubble constant which he published in 1927 ( two years before Hubble's article ), proposed the Big Bang theory of the origin of the Universe

h is a parameter in the range reflecting the uncertainty in the value of the Hubble constant H for the rate of expansion of the universe: h = H / ( 100 km / s / Mpc ).

Its companion Fomalhaut b was thought to be the first extrasolar planet ever detected by a visible light image, thanks to the Hubble Space Telescope, but infrared observations have since retracted this claim: it is instead a spherical cloud of dust.

In 1929, Edwin Hubble discovered that the distances to far away galaxies were generally proportional to their redshifts — an idea originally suggested by Lemaître in 1927.

Edwin Hubble was generally incorrectly credited with discovering the redshift of galaxies ; these measurements and their significance were understood before 1917 by James Edward Keeler ( Lick & Allegheny ), Vesto Melvin Slipher ( Lowell ), and William Wallace Campbell ( Lick ) at other observatories.

His measured value for the Hubble constant yielded the first good estimate of the age of the Universe, coming very close to the value range generally accepted today.

Other observations such as the Hubble constant, the abundance of galaxy clusters, weak gravitational lensing, globular cluster ages, are generally consistent with these, providing a check of the model, but are less accurately measured at present.

In 1929 Hubble discovered a correlation between distance and recession velocity — now known as Hubble's law.

He arranged the different groups of galaxies in what became known as the Hubble sequence.

At a meeting of the Royal Astronomical Society in Britain, a team from University of Queensland described 40 unknown " dwarf " galaxies in this constellation ; follow-up observations with the Hubble Space Telescope and the European Southern Observatory's Very Large Telescope revealed that ultra compact dwarfs are much smaller than previously known dwarf galaxies, about across.

Most known debris discs around other stars are fairly young, but the two images on the right, taken by the Hubble Space Telescope in January 2006, are old enough ( roughly 300 million years ) to have settled into stable configurations.

Subsequently, Edwin Hubble discovered an approximate relationship between the redshifts of such " nebulae " ( now known to be galaxies in their own right ) and the distances to them with the formulation of his eponymous Hubble's law.

< imagemap > File: 1990s decade montage. png | From left, clockwise: The Hubble Space Telescope floats in space after it was taken up in 1990 ; American F-16s and F-15s fly over burning oil fields and the USA Lexie in Operation Desert Storm, also known as the 1991 Gulf War ; The signing of the Oslo Accords on 13 September 1993 ; The World Wide Web gains a public face during the start of decade and as a result gains massive popularity worldwide ; Boris Yeltsin and followers stand on a tank in defiance to the August Coup, which leads to the Soviet Union's dissolution on 26 December 1991 ; Dolly the sheep is the first mammal to be cloned from an adult somatic cell ; The funeral procession of Diana, Princess of Wales, who dies in 1997 from a car crash in Paris, and is mourned by millions ; Hundreds of thousands are killed in the Rwandan Genocide of 1994 .| 420px | thumb

Hubble telescope image known as Pillars of Creation, where stars are forming in the Eagle Nebula.

It is often known colloquially as the Hubble tuning-fork diagram because of the shape in which it is traditionally represented.

At the centre of the Hubble tuning fork, where the two spiral arms meet the elliptical branch lies an intermediate class of galaxies known as lenticulars and given the symbol S0.

Nevertheless, the Hubble sequence is still commonly used in the field of extragalactic astronomy and Hubble types are known to correlate with many physically relevant properties of galaxies, such as luminosities, colours, masses ( of stars and gas ) and star formation rates.

A very large aggregation of galaxies known as the Great Attractor, dominated by the Norma cluster, is massive enough to affect the local expansion of the universe ( Hubble flow ).

* Eagle Nebula ( also known as M16 ), an astronomical object the subject of a famous Hubble Space Telescope picture

In 1929, Hubble and Milton L. Humason formulated what is now known as Hubble's Law by combining Cepheid distances to several galaxies with Vesto Slipher's measurements of the speed at which those galaxies recede from us.

In 2004 a deeper image, known as the Hubble Ultra-Deep Field ( HUDF ), was constructed from a total of eleven days of observations.

He was also the first to derive what is now known as the Hubble's law and made the first estimation of what is now called the Hubble constant which he published in 1927, two years before Hubble's article.

* Polaris, the north star, is a triple star system in which the closer companion star is extremely close to the main star — so close that it was only known from its gravitational tug on Polaris A until it was photographed by the Hubble Space Telescope in 2006.

Large numbers of the very distant galaxies seen, for example, in the Hubble Deep Field are known to be starbursts, but they are too far away to be studied in any detail.

* April-Abbé Georges Lemaître publishes in the Annales de la Société Scientifique de Bruxelles " Un Univers homogène de masse constante et de rayon croissant rendant compte de la vitesse radiale des nébuleuses extra-galactiques " proposing the theory of the expansion of the Universe, deriving what will become known as Hubble's law, making the first estimation of what will become called the Hubble constant, and proposing what becomes known as the Big Bang theory of the origin of the Universe, which he calls his ' hypothesis of the primeval atom '.

* Edwin Hubble publishes his discovery that the speed at which galaxies recede positively correlates with their distance, which becomes known as Hubble's law, the basis for understanding that the universe is expanding.

He is best known for determining the first reasonably accurate value for the Hubble constant and the age of the universe.