The immensity of the Universe presents an almost insurmountable challenge to the human imagination. Even trying to understand the distances between the planets in our Solar System is a complicated task. The complexity increases even more when we analyze galaxies. It is said that there are millions of galaxies, but it is not really known well how many galaxies are there in the universe.
In this article we are going to tell you how many galaxies are in the universe, how it is calculated and much more.
Study of galaxies
Scientists have dedicated their research to the study of galaxies to understand the composition and essence of what resides beyond the boundaries of Earth. While discovering the exact number of galaxies within the universe is a complex task, researchers have been able to find an answer so far. The number of galaxies that exist in the Universe is a question with a known answer. According to current knowledge, The estimated number of known galaxies is approximately 2 billion.
According to the Canadian Space Agency (CSA), the closest we have come to answering the question of how many known galaxies exist in the observable Universe began in 1995. This was the year the Hubble Space Telescope captured images of the sky that completely transformed our understanding of the cosmos.
For 10 days, a telescope was focused on an area apparently deserted space near the Big Dipper. Upon closer examination, the image revealed more than 3.000 cosmic entities. Most of these entities were galaxies, exhibiting a wide variety of shapes, sizes and hues, and each was at a different stage in its life cycle, according to the CSA.
As a result of the initial discovery, more ambitious projects arose that aimed to expand the field of view obtained in the mid-90s by the Hubble Space Telescope. To date, CSA notes that astronomers have discovered approximately one billion known galaxies within the Universe.
How many galaxies are there in the universe
As in human societies, counting stars is easier when they are grouped in neighborhoods. These neighborhoods of stars are called galaxies, but unlike human neighborhoods, they are vast regions of space containing an immense number of stars. Visualizing these stellar regions requires imagining spaces of enormous proportions.
To illustrate this point, we can examine our own galaxy: the Milky Way, which is classified as a spiral galaxy. The disk that constitutes our galaxy has a diameter of approximately one hundred thousand light years, with a thickness of two thousand light years. This implies that traversing the disk from one end to the other would take one hundred thousand years, assuming you could travel at the speed of light, which is impossible. Stars move around galaxies and the center of these structures is believed to contain a black hole that generates an immense gravitational force to hold the stars together. The first image of the black hole located at the core of our galaxy, the Milky Way, was recently captured.
According to Space.com, scientists believe that a typical galaxy, similar to our own, contains at least one hundred billion stars, but the number could be as high as four hundred billion. It is important to note that this is just the number of stars located within our galaxy. It is understood that there are a similar number of stars present in other galaxies throughout the universe.
The following question arises: what is the total number of galaxies that exist within the universe?
In 2016, the Hubble Space Telescope collected data implying the existence of approximately two trillion galaxies. This figure is equivalent to two billion, as the English would express it. Given the estimated number of stars per galaxy, it can be concluded that there is an incomprehensible count of stars in the universe. To be exact, There are 200.000.000.000.000.000.000.000 stars in the universe, which can also be expressed as two hundred sextillions in English dating.
The number in question is much larger than the grains of sand found on all the beaches on Earth, which is estimated to be approximately 7,5 sextillion grains.
How to count the stars
The method used to count stars is a common query. To answer this question, astronomers use specialized equipment to detect and record the light emitted by celestial bodies. The data collected from this process is then analyzed to determine the number of stars present in a particular region of space.
The Doppler effect is a well-known phenomenon that provides crucial information about the distance and mass of stars. The light radiated by galaxies can be separated into a spectrum, which is similar to the way sunlight appears when Earth's atmosphere disperses it into rainbow colors.
The distance between galaxies increases as space expands, a phenomenon that causes galaxies that are moving away from us to undergo a 'redshift'. This red shift is identified by the decrease in the frequency of the spectrum into which the light emitted by galaxies is decomposed, and serves as evidence that they are located at a greater distance from us.
By examining the luminosity of galaxies, it is possible to approximate their total mass composition and determine the percentage of stars that make up that mass.
And how many planets?
Detecting planets is a more challenging task than identifying stars or galaxies due to their lower luminosity. Since 1995, The scientific community has discovered just 5.000 exoplanets, of which only 55 reside in the habitable zone of their respective star.
Locating planets can be a difficult task, as they are often imperceptible to the naked eye. However, one of the most widely used techniques for this purpose is spectrography, which involves examining the "shadow" cast by the planet as it moves across its star.
By analyzing the light emanating from the aforementioned stars, researchers can discern anomalies that indicate the existence of planets in orbit around them. Through a computer simulation, astronomer Erik Zackrisson calculated that there could potentially be 70 quintillion planets in the universe, an astonishing figure represented by a seven followed by twenty zeros.
I hope that with this information you can learn more about how many galaxies there are in the universe and how it is calculated.