Do you know the difference between a spiral and elliptical galaxy?

Have you ever stopped to ponder how the universe came to be?  Current thinking is that the universe was formed after the “big bang” which occurred more than 13 billion years ago.  The explosive dispersal of atomic material formed the primordial structures responsible for the universe as we know it.

Expanding matter, and hot gaseous material formed into energetic stars, with their own gravitational forces, and eventually under the bonding of attractive powers and compulsion, the mighty galaxies were created and formed systems.  These collective formations of stars and planetary materials have their own individuality and for the viewing pleasure of astronomers all over the world, the varied beauty and wonder of the universe is available to us all.Difference between Spiral and Elliptical Galaxy

The evolution of galaxies

In the formative stages after the “big bang” explosion, galaxies of stars formed in irregular arrangements before any semblance of order was brought to the universe.  These randomized clusters were the melting pot for the future evolution of the systems that would become the spectacular visions that are now familiar.

As these star clusters evolve, the hot gaseous material left over from the big bang explosion continues to aggregate and formulate the creation of new stars, and these can be recognized even by telescope from Earth by the bluish tinge to the galaxy.  These formations are known as starburst galaxies.

How do galaxies grow?

Galaxies can continue to grow from within, by the conversion of gaseous material into new stars.  As primordial material aggregates and accumulates, the increased gravitational forces draw more and more material inwards, until under its own gravitation load, a star generates more energy than it absorbs, and a chain reaction of nuclear interactions results.  More stars are formed and the galaxy grows.

Galaxies have also been known to collide with other neighboring galaxies, and by a process of cannibalization, smaller galaxies are absorbed into larger galaxies, forming larger and newer formations of stars.

This may sound rather dramatic, but would believe that our own galaxy, the Milky Way is actually cannibalizing another galaxy at the present moment.  Yes our beautiful spiral galaxy is devouring a smaller elliptical galaxy.  But it is not over for us, because the Milky Way Galaxy is on a collision course with our larger neighbor, the Andromeda Galaxy, which could form a whole new elliptical galaxy in the distant future.

 

Does every galaxy have a black hole?

Scientists postulate that all galaxies must consist of massive black holes in the gravitational center of each galaxy.  If this is the case, it stands to reason that each of these black holes is required to balance the mass of the stars that make up each galaxy.  This means that black holes must be billions of times the mass of a typical star.  Not that anyone has actually seen a black hole!

No-one knows for sure if the galaxies were formed first, and each black hole created to balance, or whether the black hole and its associated gravity caused the formation of the galaxies.

Different Types of galaxies

Due to the evolutionary nature of the universe, not all galaxies are at the same growth stage, and this is typified by the variable nature of the galaxies that we can find in space.  Some galaxies are known as elliptical, due to their loosely rounded shape, with stars dispersed in an irregular formation around a gravitational center. Spiral galaxies are widely recognized, not only because the Milky Way is if spiral formation, but because the delicate formation of stars around a central axis are the most attractive.  Other types of formations are known as lenticular galaxies and irregular galaxies which differ in terms of their geometric patterns.

 

The Milky Way Galaxy

Although impossible to view from within, the Earth and the Sun are but a speck in one of the spiral arms of a barred spiral galaxy know as the Milky Way.  We are only one of an estimated 200 billion stars in the Milky Way, and we sit on a non-descript spiral arm part way between the galactic center and the outer arms of the galaxy.  The Milky Way was named after the aggregation of light from the billions of stars on the opposite side of our galaxy, which, when viewed from side on and laterally through the Milky Way, appear as a bright, narrow band in the night sky.

The more we learn about astronomy, the more we learn about our origins!

What about our neighbors?

 

Difference between Spiral and Elliptical GalaxyAndromeda — another spiral galaxy

Our nearest galactic neighbor is the mighty Andromeda galaxy, which is one of the largest galaxies in our portion of space which is made up of about 45 galaxies in total.

The Andromeda galaxy is also a spiral galaxy and it contains more than a trillion stars. At more than 2.5 million light years from Earth, you don’t need to worry about a collision in the near future!

 

Spiral galaxies

Spiral galaxies are the easiest to recognise of all the deep space objects consisting of the distinctive spiral arms which radiate from a glowing central mass if older stars.  Spiral galaxies are evolving structures, with newer stars being created from gaseous materials in the spiral arms, and evolving longer and longer trails of glittering lights.

Some spiral galaxies have several spiral arms, radiating in trailing paths and rotating around the gravitational center.  Some spirals have fewer arms that attached more tightly, whilst others seem to have almost detached their appendages, whilst still rotating in formation.

 

The barred spiral galaxy

Difference between Spiral and Elliptical GalaxyThe most common type of spiral galaxy is the barred spiral galaxy.  These are easily recognizable as the arms of a barred spiral galaxy don’t connect right to the galactic center.  The arms of these galaxies seem to connect to a central line of stars, with the spiral arms trailing from each end of the central bar.


Elliptical galaxies

Although not as common amongst star formations the elliptical galaxies can form into the largest collections of stars in the whole universe.  These galaxies are the earliest formations of stars, which have yet to form into a regular pattern.

Without a defined structure, elliptical galaxies can be oval shaped, and tend to consist of stars that orbit around a loosely formed center of gravity. These elliptical star clusters can also be formed by the collision between two galaxies, which disrupts the regular spiral form into an elliptical mass of stars.

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Irregular galaxies

Difference between Spiral and Elliptical Galaxy

The other type of galaxy that has been observed in deep space does not have the distinctive or regular shape like spirals or ellipticals and are hence known as irregular galaxies.  These formations often appear as a chaotic arrangement of stars, with no central aggregation or nucleus and no apparent central bar or spiral arms.

These galaxies are quite common amongst galaxies, and are also called irregular star clusters, and may have been formed not so much by a collision between two galaxies, but by a near miss of a gravitational encounter.  Such a close approach may result in the deformation of the original regular pattern, and the resultant loss of formation.

 

 

 

 

 

Colliding galaxies

 

There can be no more spectacular astronomical vision than of two colliding galaxies to underscore the immense forces at a galactic level of interaction.

Enormous gravitational forces of attraction, even across remote reaches of the deep sky, can cause two monumental structures to be drawn ever closer.  Don’t worry, the inter-spatial gaps between stars is so vast, that a galactic collision doesn’t usually cause another big bang!  So long as the individual stars don’t actually collide, it is the enormous gravitational forces that do the work, and create the stunning images that we see when two galaxies interact on a truly vast and inter-galactic scale.  Maybe after millions of years a new galaxy will be created from these two, and who knows what it will look like after that?

Difference between Spiral and Elliptical Galaxy

 

 

If you want to see some of these incredible wonders of the universe, please read our reviews on the best telescope.

 

 

 

 

 

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