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jimjohnson
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The Hubble deep sky image is 3 x3 arc minutes and shows an estimated 10,000 galaxies. What percent is 3 x 3 arc minutes of the total area? If this ratio is known, one could estimate the number of total galaxies. Thanks
jimjohnson said:What percent is 3 x 3 arc minutes of the total area?
Not assuming a finite universe. These are just measures of the visible galaxies. The total number, including the parts of the universe we can't observe, is almost certainly vastly larger. How much larger? We don't know.jimjohnson said:Thanks, I was having a mental block. The result is 5.2 x E10 galaxies which is similar to other estimates assuming a finite universe.
I'd just mention that this is a significant underestimate, as there are a great many galaxies that are too dim for Hubble to see.jimjohnson said:The Hubble images support an estimate of 155-165 billion galaxies in the observable universe.
Comments?
Scientists use various methods to estimate the number of galaxies in the universe, such as counting the number of galaxies in a small portion of the sky and extrapolating it to the entire observable universe, using computer simulations, and analyzing the cosmic microwave background radiation.
The latest estimates suggest that there are approximately 2 trillion galaxies in the observable universe.
It is possible that there are more galaxies beyond the observable universe, but we currently have no way of observing them due to the limitations of the speed of light and the expansion of the universe.
Yes, the estimated number of galaxies has changed over time as our technology and understanding of the universe has improved. In the 1990s, it was estimated that there were around 100 billion galaxies, but recent studies suggest that there are at least 10 times more galaxies than previously thought.
Estimating the number of galaxies is important for understanding the structure and evolution of the universe. By knowing the number of galaxies, scientists can also estimate the amount of dark matter and dark energy in the universe, which are key components in our understanding of the universe's expansion and formation.