Hubble’s scheme divides regular galaxies into 3 broad classes - ellipticals, lenticulars and spirals - based on their visual appearance (originally on photographic plates). A fourth class contains galaxies with an irregular appearance. To this day, the Hubble sequence is the most commonly used system for classifying galaxies, both in professional astronomical research and in amateur astronomy.
Classes of galaxies
Ellipticals
On the left (in the sense that the sequence is usually drawn) lie the ellipticals. Elliptical galaxies have smooth, featureless light distributions and appear as ellipses in photographic images. They are denoted by the letter E, followed by an integer representing their degree of ellipticity on the sky. By convention, is ten times the ellipticity of the galaxy, rounded to the nearest integer, where the ellipticity is defined as for an ellipse with semi-major and semi-minor axes of lengths and respectively. The ellipticity increases from left to right on the Hubble diagram, with near-circular (E0) galaxies situated on the very left of the diagram. It is important to note that the ellipticity of a galaxy on the sky is only indirectly related to the true 3-dimensional shape (for example, a flattened, discus-shaped galaxy can appear almost round if viewed face-on or elliptical if viewed at an angle). Observationally, the most flattened elliptical galaxies have ellipticities e=0.7 (denoted E7). This is consistent with their being truly ellipsoidal structures rather than disks viewed at a range of angles.
This discovery showed that the universe was far larger than anyone had previously imagined.Hubble further revolutionised astronomy with the 'Hubble Classification Scheme,' which categorises galaxies into spiral, elliptical, or irregular shapes.
EdwinHubble tried to bring some structure to the different shapes by developing his galaxy classification scheme to articulate not only the shape but also the sub categories within them ...NASA, ESA, and The Hubble Heritage Team (STScI/AURA).
RBI tightens norms for banks, NBFCs investing in Alternative Investment FundsThe misconception is due to the Hubble tuning fork of galactic classification, which visually shows galaxy types proceeding ...
This misconception is due to the Hubble tuning fork of galactic classification, which visually shows galaxy types proceeding from elliptical to spiral, in a sequence that could easily be interpreted as a temporal evolution.
The Hubble morphological classification system was determined in 1926 by the great American astronomer Edwin Hubble, who broadly divided galaxies into spirals (S), ellipticals (E), lenticulars (S0) ...
Image. Jim Misti ...NGC 6946, also catalogued as Caldwell 12, is an intermediate spiral galaxy (it has the classification SAB(rs)cd, under the Hubble/de Vaucouleurs system) straddling the boundary between the constellations of Cygnus and Cepheus ... Image ... .
In the infinite reaches of space, there are probably many different celestial objects that defy the classifications humans have made for them. The Hubble telescope has found another such object ... Quasars are a particular type of AGN ... .
Just recently, evidence suggesting that there is an active volcano on Venus was reported by researchers ...Louis ... Advertisement. The map featuring all the volcanic features on Venus ... Louis ... Strange Cosmic Object That Defies Classification Spotted by Hubble.
At the time, the area included Asia and Oceania... the strongest class of flares in our logarithmic classification that puts flares in an A, B, C, M, or X class ... Advertisement ... NASA/SDO ... Strange Cosmic Object That Defies Classification Spotted by Hubble ... .
NASA, ESA and the HubbleHeritage Team (STScI/AURA) ...Messier 81’s morphological classification (Hubble/de Vaucouleurs) is SA(s)ab, indicating that no central bar is present and that its spiral arms are not that tightly wound.
He explains how a century ago, American astronomer EdwinHubble used the Mount Wilson Observatory in California to sort different types of nearby galaxies, creating the classification system most astronomers use today.
Finally, they only picked galaxies with a similar Hubble type, a classification system that groups galaxies based on their shape ...There are other refinements possible within the Hubble classification ...
A simple representation of Hubble Classifications, with spiral galaxies on the right (barred galaxies on the lower branch) and elliptical galaxies on the left.
representing their degree of ellipticity on the sky. By convention, 
for an ellipse with semi-major and semi-minor axes of lengths 
and 
respectively. The ellipticity increases from left to right on the Hubble diagram, with near-circular (E0) galaxies situated on the very left of the diagram. It is important to note that the ellipticity of a galaxy on the sky is only indirectly related to the true 3-dimensional shape (for example, a flattened, discus-shaped galaxy can appear almost round if viewed face-on or elliptical if viewed at an angle). Observationally, the most flattened elliptical galaxies have ellipticities e=0.7 (denoted E7). This is consistent with their being truly 
