The Milky Way is just a tiny particle in a Universe made up of countless galaxies. But how many galaxies are there? This seemingly simple question is more complicated than it seems.
The first problem is that we only see a small part of the Universe, even with the most powerful telescopes. The observable Universe is the part from which light has managed to reach us in 13.8 billion years. But due to the expansion of the Universe, the observable part extends about 46 billion light years in all directions. That’s only about 3% of the entire Universe.
The second problem is the countless number of galaxies. We can only estimate their number based on observations in small areas of the sky, which are then multiplied by the size of the sky. But the question arises about what is considered a galaxy. There are giant galaxies with a mass 10 times the mass of the Milky Way, and small galaxies, up to dwarf galaxies.
To make estimates, scientists determine the minimum mass of a galaxy. If we accept the conservative limit of one million solar masses, the number of galaxies in the Universe is estimated to be in the range of 1 to 2 trillion. There were more galaxies earlier in the history of the Universe, so these estimates are averages over a long period.
However, new research using the New Horizons spacecraft, which is outside the Solar System, suggests that the number of galaxies may be much smaller than we thought. According to this study, there could be 100 to 200 billion galaxies in the visible Universe.
Thus, the number of galaxies in the observable Universe can range from 100 billion to 2 trillion. If we take into account that we only see 3% of the Universe, we can make a rough estimate of the total number of galaxies in the entire Universe.
We previously reported on how the oldest galaxy in the Universe challenged cosmic theories of evolution.
According to livescience.com
