How many galaxies exist in the universe? The answer to this question is very difficult. Many astronomers of the past tried to understand how many galaxies are in the universe. Counting them seems an impossible task. When the bill goes to billions, it takes some time to add. Another problem is the limited number of our tools. To obtain the best image, the telescope should have a large aperture (the diameter of the main mirror or lens) and be located above the atmosphere to avoid distortion from the Earth’s air.
Hubble Field
Perhaps the most resonant example of the aforementioned fact is the extremely deep Hubble field - an image obtained by combining photographs taken over ten years from the telescope of the same name. According to NASA, the telescope observed a small portion of the sky for 50 days. If you hold your thumb at arm's length to cover the moon, the deep-field area will be the size of a pinhead.
Collecting faint light over many hours of observation, the Hubble telescope discovered thousands of galaxies, both close and very distant, which takes pictures taken from it, the most complete image of the universe. So even if there are thousands of galaxies in this small spot in the sky, imagine how much more can be found in other parts of the universe.
Expert Ratings
Although the scores of different experts vary, answers to questions like "How many galaxies are there in the universe?" can be expressed in astronomical numbers: from 100 to 200 billion. When the James Webb Space Telescope launches in 2020, NASA is expected to reveal even more information about the early galaxies in the universe.
Technology truly works wonders. As far as modern astronomers know, the Hubble telescope is the best tool for counting and estimating how many galaxies are known in the Universe. The telescope, launched in 1990, initially had a distortion on the main mirror, which was corrected during a shuttle visit to it in 1993. Hubble has also undergone several updates and business visits until its most recent mission in May 2009. Is the universe infinite, how many galaxies, how many planets are there? Apparently, we still have to find out in the future.
Big Dipper
In 1995, astronomers pointed a telescope at what seemed like an empty area of Ursa Major and collected observations for ten days. As a result, about 3,000 faint galaxies were discovered in one frame, which became fading, like the 30th magnitude. For comparison: A polar star is about the second magnitude. This component of the image was called the Hubble Deep Field and was the farthest ever seen in the universe.
When the aforementioned American telescope was thoroughly modernized, astronomers repeated the experiment twice. In 2003 and 2004, scientists discovered about 10,000 galaxies in a small place in the constellation Fornax.
In 2012, again with the help of modernized tools, scientists used a telescope to look at part of an ultra-deep field. Even in this narrower field of view, astronomers were able to detect about 5,500 galaxies. Researchers dubbed this an "extraordinary deep field."
The invisible billions
Whatever tool is used, the method of estimating how many galaxies in the universe are more or less the same. You take the part of the sky captured by the telescope (in this case, the Hubble). Then, using the ratio of a piece of sky to the entire universe, you can determine how many galaxies are in the universe.
Cosmological principle and age of the Universe
One example of the cosmological principle in the study of the Universe is the cosmic microwave background - radiation, which is the remnant of the early stages of the Universe after the Big Bang.
Measurements of the expansion of the universe through observations of galaxies moving away from us show that it is about 13.82 billion years old. However, as the universe grows older and larger, galaxies will move farther and farther away from the earth. This will make them more difficult to distinguish.
The Universe is expanding faster than the speed of light (which does not violate Einstein's speed limit, because the expansion is connected with the Universe itself, and not with objects traveling through it). In addition, the universe is accelerating in its expansion.
It is here that the concept of "observable Universe" comes into play - the Universe that we can see. According to many experts, in 1-2 trillion years, this will mean that there will be galaxies that are outside the spaces that we can see from Earth.
Change of light
We can only see light from galaxies that have had enough time to reach us - that is, to approach a fairly close distance to the Milky Way. This does not mean that these objects are all that are in space. Hence the definition of "observable universe."
The future of the Milky Way
Galaxies also change over time. The Milky Way is on a collision path with the nearby Andromeda galaxy, and they will both merge in about four billion years. Later, other galaxies in our local group will eventually unite. Astronomers believe that the inhabitants of these future galaxies will observe the darker Universe.
When the first civilizations appeared, they had no evidence of the existence of a universe with one hundred billion galaxies. Therefore, our descendants will not see the expansion of the universe. They probably won’t even be able to understand that there was a Big Bang.
If we, ordinary people, want to know how many galaxies and planets are in the Universe, then astronomers are more interested in how space itself was formed. According to NASA, galaxies give an idea of how matter is organized in the universe - at least on a large scale. Scientists are also interested in particle types and quantum mechanics on the small side of the observed spectra.
Early galaxies
By examining some of the earliest galaxies and comparing them with today's galaxies, we can understand their growth and development. An advanced telescope called Webb will allow scientists to collect data on the types of stars that existed in the very first galaxies. Subsequent observations using spectroscopy of hundreds or thousands of galaxies will help researchers understand how elements heavier than hydrogen formed and accumulated as star clusters formed over the centuries. These studies will also reveal the details of their merger and shed light on many other processes.
Dark matter
Scientists are also interested in the role that dark matter plays in the nucleation of galaxies. This is a very interesting question. While part of the universe is visible in objects such as galaxies or stars, dark matter - which makes up most of the cosmos - is invisible at all. How many galaxies in the universe? The number of these objects is not thoroughly known, but it is definitely more than a hundred billion.
Conclusion
When you look at the night sky through the veil of stars and the plane of the Milky Way, you cannot help but feel small in front of the great abyss of the Universe, which is outside the sky. Although almost all of them are invisible to our eyes, the observable Universe, stretching for tens of billions of light years in all directions, contains a fantastically large number of galaxies.
The number of known star clusters increased with the development of telescopic technologies - from thousands to millions, from billions to trillions. If we carried out the simplest analysis using the best technologies to date, we would say that there are 170 billion galaxies in our Universe. But we will discover even more of these objects, because now it is believed that there are actually not less than two trillion of them.
Someday we will count them all. We will direct our telescopes to the sky, collect every photon emitted by the stars and find every cosmic object, no matter how weak its glow.
But in practice this will not work. Our telescopes are limited in size, which in turn limits the number of photons that they can collect. There is a relationship between how faint you can see and how much sky you can “cover” with an optical device. Some part of the Universe is darkened due to dark matter located within its limits. The farther away the object, the weaker it seems.
So we can only look at the illuminated part of the Universe, without peering into dark matter, stars or galaxies. Scientists have collected data on hundreds of dim, distant space objects. They are still hoping to find out what distant worlds actually look like. And we, simple observers, hope so as much as they do.