How many galaxies are there in the Universe? The answer to this question is very difficult. Many astronomers of the past tried to figure out how many galaxies there are in the universe. Counting them seems like an impossible task. When the bill goes into the billions, it takes some time to add up. Another problem is the limited number of our tools. To get the best image, the telescope should have a large aperture (the diameter of the primary mirror or lens) and be positioned above the atmosphere to avoid distortion from Earth's air.
Hubble Field
Perhaps the most resonant example of the above fact is the Hubble Extreme Deep Field - an image obtained by combining photographs taken over a period of ten years from the telescope of the same name. According to NASA, the telescope observed a small area of the sky for 50 days. If you hold your thumb at arm's length to cover the moon, the area of deepmargins will be the size of the head of a pin.
By collecting faint light over many hours of observation, the Hubble telescope has discovered thousands of galaxies, both close and very distant, making images 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 many more can be found elsewhere in the universe.
Expert assessments
Although experts vary in their assessments, 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 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 distortion on its primary mirror, which was corrected during a shuttle visit in 1993. Hubble also underwent several upgrades and missions until its last mission in May 2009. Is the Universe infinite, how many galaxies, how many planets are there in it? Apparently, we have yet to find out in the future.
Ursa Major
In 1995, astronomers pointed a telescope at what appeared to be an empty area of Ursa Major and collected ten days of observations. ATAs a result, about 3000 faint galaxies were found in one frame, which became dim, like the 30th magnitude. For comparison: the North Star has about the second magnitude. This component of the image was called the Hubble deep field and was the most distant one ever seen in the universe.
When the aforementioned American telescope was thoroughly upgraded, the astronomers repeated the experiment twice. In 2003 and 2004, scientists discovered about 10,000 galaxies in a small area in the constellation Fornax.
In 2012, again with upgraded instruments, scientists used a telescope to look at part of the ultra-deep field. Even in this narrower field of view, astronomers were able to detect about 5,500 galaxies. The researchers dubbed it the "Extreme Deep Field".
Invisible billions
Whichever tool is used, the method of estimating how many galaxies there are in the universe is more or less the same. You take a part of the sky taken by a telescope (in this case, Hubble). Then, using the ratio of the piece of sky to the entire universe, you can determine how many galaxies there are in the universe.
Cosmological principle and the age of the Universe
One example of a cosmological principle in the study of the universe is the cosmic microwave background, radiation that is leftover from the early stages of the universe after the Big Bang.
Measuring the expansion of the universe through the observation of galaxies moving awayfrom us, show that it is about 13.82 billion years old. However, as the universe gets older and bigger, galaxies will move farther and farther away from Earth. This will make them harder to see.
The universe is expanding faster than the speed of light (which doesn't violate Einstein's speed limit, because the expansion is due to the universe itself, not the objects traveling through it). In addition, the universe is accelerating in its expansion.
This is where the "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 of the spaces that we can see from Earth.
Changing light
We can only see light from galaxies that have had enough time to get to us - that is, get close enough to the Milky Way. This does not mean that these objects are all there is 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 course with the nearby Andromeda Galaxy, and the two will merge in about four billion years. Later, other galaxies in our local group will eventually merge. Astronomers believe that the inhabitants of these future galaxies will observe a darker universe.
When the firstcivilization, they had no evidence of a universe with a hundred billion galaxies. Therefore, our descendants will not see the expansion of the universe. They probably won't even realize that the Big Bang happened.
If we, ordinary people, want to know how many galaxies and planets there are in the Universe, then astronomers are more interested in how the cosmos itself was formed. According to NASA, galaxies provide insight into 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 observed spectra.
Early galaxies
By studying some of the earliest galaxies and comparing them to today's, 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. Follow-up 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 birth of galaxies. This is a very curious question. While part of the universe is visible in objects such as galaxies or stars, dark matter iswhat makes up most of the cosmos is invisible at all. How many galaxies are in the universe? The number of these objects is not completely 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 can't help but feel small in front of the great abyss of the universe that lies beyond the firmament. Although almost all of them are invisible to our eyes, the observable universe, stretching tens of billions of light years in all directions, contains a fantastically large number of galaxies.
The number of known star clusters has increased with the development of telescopic technology - from thousands to millions, from billions to trillions. If we were to do the simplest analysis, using today's best technology, we would say that there are 170 billion galaxies in our universe. But we will discover even more of these objects, because it is already believed that there are actually no less than two trillion of them.
Someday we will count them all. We will point our telescopes at the sky, collect every photon emitted by the stars, and detect every cosmic object, no matter how faint its glow.
But it won't work in practice. Our telescopes are limited in size, which in turn limits the number of photons they can collect. There is a relationship between how faint an object you can see and how much of the sky you can "cover" with an optical instrument. Some part of the universeobscured due to the dark matter within it. The further away an object is, the fainter it appears.
So we can only look at the illuminated part of the universe, not 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 really look like. And we mere observers hope so as much as they do.
