Because the deeper you look into space, the further you see back in time, we can conclude that galaxies several billions of light-years away formed fairly soon after the big bang. While most galaxies formed early, data indicates that some galaxies have formed within the past few billion years — relatively recently in cosmic terms.
The early universe was filled mainly with hydrogen and helium, with some areas slightly denser than others. Gravity caused the gas in these clouds to collapse and form the first generation of stars. These first stars rapidly burned out. Gravity continued to collapse the clouds. As other clouds came close to each other, gravity sent them careening into one another and knitted the clouds into larger, spinning packs.
As the clouds further collapsed, they became rotating disks, which amassed more gas and dust. New stars formed, creating extensive spiral arms filled with colonies of stars. Sprinkled along the periphery were globular clusters, along with a halo of gas, dust and dark matter.
While Hubble is unable to see the very first galaxies, it can track the development of galaxies over much of cosmic time. The series of Hubble Deep Field images and other deep surveys have uncovered galaxies at many different distances out in the universe, and therefore at many different times in their development. Farther galaxies, seen earlier in time, have less developed structure. Nearer galaxies, seen later in time, grow to resemble the familiar galaxy shapes we see in the local universe.
The Building Blocks of the Universe. On This Page. Types of Galaxies. What Kinds of Galaxies Are There? This graphic compares illustrations of the three main types of galaxies top with actual photos of galaxies bottom that fit the categories. Credit: A. Feild STScI. Dark Matter. What Is Dark Matter? This detailed view of our galactic next-door neighbor, the Andromeda galaxy, contains over million resolved stars and thousands of star clusterss. The panorama sweeps from the galaxy's central bulge across lanes of stars and dust to the sparser outer disk.
Dalcanton, B. Williams, and L. The Bullet Cluster was formed after the collision of two large clusters of galaxies. Hot gas detected by Chandra in X-rays is seen as two pink clumps in the image and contains most of the "normal," or baryonic, matter in the two clusters. The bullet-shaped clump on the right is the hot gas from one cluster, which passed through the hot gas from the other larger cluster during the collision.
An optical image from the Hubble and Magellan telescopes shows the galaxies in orange and white. The blue areas in this image depict where astronomers find most of the mass in the clusters. Most of the matter in the clusters blue is clearly separate from the normal matter pink , giving direct evidence that nearly all of the matter in the clusters is dark.
Markevitch et al. Irregular Galaxy Irregular galaxies are composed of gasses, dust, stars, nebulous formations, neutron stars, black holes and other elements common to all galaxies. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. However, you may visit "Cookie Settings" to provide a controlled consent. Read more on our privacy policy here.
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The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. Galaxy Formation and Evolution. The way in which different types of galaxies are formed is dependent upon the interactions of each component during the original formation of the galaxy.
For example, collisions of space masses are likely to occur which may then force certain pieces to the outer edges of the galaxy. This interaction would then potentially form the arms of a spiral galaxy. Certain galaxies are so bright that you can observe them visually with the unaided eye. This means that you do not need a telescope or binoculars to the galaxy, you just need to look up at the right time and place.
Light pollution can spoil the view, so be sure to attempt viewing these naked-eye galaxies from a dark-sky location. Here is a list of the brightest galaxies you can observe with the naked-eye under clear, moonless conditions. I have personally observed the 2 brightest northern hemisphere galaxies from a dark sky location Bortle Scale class 2.
Although this is a long-exposure photograph, this is a useful exaggerated representation of what you can expect to see under pristine skies. The Andromeda Galaxy is visible to the naked eye from a dark sky location. Certain constellations, such as Virgo , contain galaxy clusters. The Virgo Cluster contains about galaxies, possibly even up to In the following video, the author explains how galaxies are categorized according to their apparent shape.
The shape of the galaxy gives astronomers clues as to the age and types of stars found within it. Types of Galaxies There are four distinct types of galaxies in the universe, elliptical, spiral, barred spiral, and irregular.
Spiral Galaxies Named for their shape, spiral galaxies are the most common type of galaxy in the universe. Galaxy Type Chart Tuning-fork-style diagram of the Hubble sequence Wikipedia There are many beautiful examples of spiral galaxies in the night sky.
Lenticular Galaxy Briefly elaborating, S0 galaxies are like a combination between a spiral galaxy and elliptical galaxy because of the bulge and disk that they do have, like spiral galaxies, but they do not have a spiral-like structure. Barred Spiral Galaxies Although similar to spiral galaxies, barred spiral galaxies differ in their shape slightly. Elliptical Galaxies These elliptical galaxies are classified by their ovular shape and lack of central bulge.
The 0 represents the most round elliptical galaxy and 7 means that the galaxy is very ovular. Irregular Galaxies As the name implies, irregular galaxies are all quite unique. Formation Clusters and clouds of stars and dust making their way through the universe are thought to be the very beginnings of galaxy formation.
List of Naked Eye Galaxies Certain galaxies are so bright that you can observe them visually with the unaided eye. Large Magellanic Cloud Magnitude 0. Types of Galaxies Video In the following video, the author explains how galaxies are categorized according to their apparent shape.
This is an excellent summary of the different types of galaxies in the universe. Search AstroBackyard. Popular Post. Star Trackers.
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