Tuning-fork style diagram of the Hubble sequence

This tuning-fork style diagram of the Hubble sequence was created on the base of the Wikimedia Commons file: Hubble sequence photo.png. [commons.wikimedia.org/ wiki/ File:Hubble_ sequence_ photo.png]
"The Hubble sequence is a morphological classification scheme for galaxies invented by Edwin Hubble in 1936. It is often known colloquially as the Hubble tuning fork diagram because of the shape in which it is traditionally represented.
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." [Hubble sequence. Wikipedia]
The astronomical diagram example "Tuning-fork style diagram of the Hubble sequence" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Astronomy solution from the Science and Education area of ConceptDraw Solution Park.

"The Summer Triangle is an astronomical asterism involving an imaginary triangle drawn on the northern hemisphere's celestial sphere, with its defining vertices at Altair, Deneb, and Vega, the brightest stars in the three constellations of Aquila, Cygnus, and Lyra, respectively. ...
Near midnight the Summer Triangle lies virtually overhead at mid-northern latitudes during the summer months, but can also be seen during spring in the early morning to the East. In the autumn the summer triangle is visible in the evening to the West well until November. From the southern hemisphere it appears upside down and low in the sky during the winter months." [Summer Triangle. Wikipedia]
This example was redesigned from the Wikimedia Commons file: Summer triangle network.jpg. [commons.wikimedia.org/ wiki/ File:Summer_ triangle_ network.jpg]
This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication. [creativecommons.org/ publicdomain/ zero/ 1.0/ deed.en]
The astronomical diagram example "Summer triangle network" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Astronomy solution from the Science and Education area of ConceptDraw Solution Park. www.conceptdraw.com/ solution-park/ science-education-astronomy

"Pegasus is a constellation in the northern sky, named after the winged horse Pegasus in Greek mythology. It was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy, and remains one of the 88 modern constellations.
The brightest star in Pegasus is the orange supergiant Epsilon Pegasi, also known as Enif, which marks the horse's muzzle. Alpha (Markab), Beta, and Gamma, together with Alpha Andromedae (Alpheratz or Sirrah) form the large asterism known as the Square of Pegasus. Twelve star systems have been found to have exoplanets." [Pegasus (constellation). Wikipedia]
This example was redesigned from the Wikimedia Commons file: Pegasus network.jpg. [commons.wikimedia.org/ wiki/ File:Pegasus_ network.jpg]
This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication. [creativecommons.org/ publicdomain/ zero/ 1.0/ deed.en]
The astronomical diagram example "Pegasus network" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Astronomy solution from the Science and Education area of ConceptDraw Solution Park.

"Orion is a prominent constellation located on the celestial equator and visible throughout the world. It is one of the most conspicuous and recognizable constellations in the night sky. It was named after Orion, a hunter in Greek mythology. Its brightest stars are Rigel (Beta Orionis) and Betelgeuse (Alpha Orionis), a blue-white and a red supergiant respectively. Many of the other brighter stars in the constellation are hot, blue supergiant stars. The three stars in the middle of the constellation form an asterism known as Orion's belt. The Orion Nebula is located south of Orion's belt." [Orion (constellation). Wikipedia]
This example was redesigned from the Wikimedia Commons file: Orion network.jpg. [commons.wikimedia.org/ wiki/ File:Orion_ network.jpg]
This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication. [creativecommons.org/ publicdomain/ zero/ 1.0/ deed.en]
The astronomical diagram example "Orion network" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Astronomy solution from the Science and Education area of ConceptDraw Solution Park.

This astronomic diagram example was redesigned from the Wikimedia Commons file: Extragalactic distance ladder.JPG.
[commons.wikimedia.org/ wiki/ File:Extragalactic_ distance_ ladder.JPG]
Red boxes: Technique applicable to star-forming galaxies.
Green boxes: Technique applicable to Population II galaxies.
Cyan boxes: Geometric distance technique.
Pink box: The planetary nebula luminosity function technique is applicable to all populations of the Virgo Supercluster.
Solid lines: Well calibrated ladder step.
Dashed lines: Uncertain calibration ladder step.
"The cosmic distance ladder (also known as the extragalactic distance scale) is the succession of methods by which astronomers determine the distances to celestial objects. A real direct distance measurement of an astronomical object is possible only for those objects that are "close enough" (within about a thousand parsecs) to Earth. The techniques for determining distances to more distant objects are all based on various measured correlations between methods that work at close distances with methods that work at larger distances. Several methods rely on a standard candle, which is an astronomical object that has a known luminosity.
The ladder analogy arises because no one technique can measure distances at all ranges encountered in astronomy. Instead, one method can be used to measure nearby distances, a second can be used to measure nearby to intermediate distances, and so on. Each rung of the ladder provides information that can be used to determine the distances at the next higher rung." [Cosmic distance ladder. Wikipedia]
The astronomy diagram sample "Extragalactic distance ladder" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Astronomy solution from the Science and Education area of ConceptDraw Solution Park.