How many galaxie

Because elliptical galaxies contain older stars and less gas than spiral galaxies, it seems that the galaxy types represent part of a natural evolution: As spiral galaxies age, interact, and merge, they lose their familiar shapes and become elliptical galaxies. But astronomers are still working out the specifics, such as why elliptical galaxies follow certain patterns in brightness, size, and chemical composition. The universe's first stars ignited some million years after the big bang, the explosive moment Gravity had sculpted the first galaxies into shape by the time the universe turned million years old , or less than 3 percent of its current age.

Astronomers now think that nearly all galaxies— with possible exceptions —are embedded in huge haloes of dark matter. Theoretical models also suggest that in the early universe, vast tendrils of dark matter provided normal matter the gravitational scaffold it needed to coalesce into the first galaxies. But there are still open questions about how galaxies form. Some believe that galaxies formed from smaller clusters of about one million stars, known as globular clusters , while others hold that galaxies formed first, and later birthed globular clusters.

It's also difficult to figure out how many of a given galaxy's stars formed in situ from its own gas , versus forming in another galaxy and joining the party later. By letting astronomers peer into the universe's farthest reaches—and earliest moments—instruments such as NASA's James Webb Space Telescope should help resolve lingering questions. All rights reserved. Galactic clusters and mergers Some galaxies occur alone or in pairs, but they are more often parts of larger associations known as groups, clusters, and superclusters.

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There may be far better options for humanity to travel in space then just with the speed of light. If these options remain only purely hypothetical, such as the much-coveted wormholes, then we are indeed trapped within our own galaxy.

Another aspect we should take into consideration is the fact that galaxies move around, just like planets, and stars do. It has been proven that many galaxies are getting further and further away from us.

If we would want to reach other galaxies, our best chance is to go straight towards a galaxy which is coming our way, like the Andromeda Galaxy , for example. The Andromeda Galaxy is on a collision course with our Milky Way Galaxy; however, this will happen in around 4.

This number is far too great to help us in our intergalactic space travel endeavor. Since the Universe is so vast and complex, one might assume that other Universes exist.

There is only one Universe we currently know of, and that is the Universe in which we already live. The existence of other Universes certainly seems possible; however, we are still on the process of studying our own before hunting for others.

We know too little about our own Universe, and deciphering it is the key to finding out if there are other Universes out there. How Many Galaxies are there in the Universe? The Milky Way consists of a bright disk, a slowly spinning platter of stars and gas that contains most of the stars we see.

Far away, in the center of the galaxy, lies a supermassive black hole containing around 4. In recent times, astronomers have discovered that supermassive black holes in the centers of galaxies are the norm. Nearly all galaxies, except for dwarfs, have them. The Milky Way is hardly alone in the cosmos. It belongs to a group of at least 54 objects called the Local Group of galaxies, a name Hubble gave to this local cloud of objects as he mapped the nearby cosmos.

But each of these big three spirals has a cloud of attendant galaxies, too. The diameter of the Local Group is about 10 million light-years, some times the diameter of the Milky Way.

And moving outward into the deeper universe, we encounter more examples of those billion galaxies. These majestic islands of stars and gas exist in groups, like our Local Group, but also in larger assemblages called clusters and very large ones called superclusters. Despite the overall expansion of the universe, meaning that most galaxies are moving away from each other as the cosmos grows, gravity keeps smaller numbers of galaxies bound to each other on their journeys.

Our Local Group, for example, is a member of the so-called Virgo Cluster of galaxies, named so because its richly populated center lies in the constellation Virgo in our sky. The Virgo Cluster contains at least 1, galaxies and is centered some 54 million light-years from Earth.

This line of galaxies contains supermassive elliptical galaxies such as M84 and M86, and a variety of spiral galaxies, too. For backyard astronomers, this playground of galaxy types is one of the really entrancing areas of the sky, and it is best visible on springtime evenings under clear, moonless conditions. Most of the Virgo Cluster galaxies contain supermassive black holes in their centers. M87 is quite an example. A cluster containing 1, galaxies is one thing, but much larger assemblages of galaxies also exist.

The Virgo Cluster itself is a member of the so-called Virgo Supercluster, which holds thousands of galaxies on a scale an order of magnitude larger yet. This amazingly large framework stretches some million light-years across, and is one of about 10 million superclusters that make up the entire cosmos. Despite the huge number of galaxies existing in the Virgo Supercluster, astronomers now know that most of the space in this volume is essentially empty.

The diameters of these great voids range from dozens to hundreds of millions of light-years. Filamentary chains of galaxies wind their way around the dark, empty spaces. On large scales, galaxies in clusters and superclusters are like soap bubbles, with galaxies coating the surfaces and voids lying in between. By the end of the s, astronomers had identified the Great Wall, a sheet of galaxies measuring million light-years across. More recently, the Sloan Digital Sky Survey uncovered the Sloan Great Wall, an assemblage of galaxies at least twice the size of the Great Wall, which covers a long dimension of some 1.

As astronomers discovered more and more distant galaxies, they found that some large mass seemed to be tugging on the local universe, pulling us in the direction of the southern constellations Triangulum Australe and Norma.

Called the Great Attractor, this anomaly, some million light-years away, puzzled astronomers. They eventually discovered that an even larger mass in that direction was pulling us. This mammoth structure, called the Shapley Supercluster, is million light-years away and contains the greatest concentration of galaxies in our local part of the cosmos. Additional surprising discoveries have occurred, too. The distinction lies in dark matter halos: galaxies and dwarf galaxies have them, while star clusters do not.

So to estimate how many galaxies we could theoretically observe, we would want to know the number of dark matter halos in the observable universe, and the probability that any halo with a certain mass would form stars, explains Henry Ferguson Space Telescope Science Institute. Currently, there is no consensus on these values, but estimating the galactic population with this method could result in a number much higher than billion.

Did you know that a supermassive black hole lurks in almost every large galaxy? Community Leaders: Notable Astronomers. By: Richard S. Wright Jr.