🌍 How many galaxies are there in the observable Universe? It's a question we can't yet answer precisely. But we can make an estimate!
A study conducted by the University of Nottingham in 2020 has revealed that there may be many more galaxies than we thought. Just a few years ago, scientists estimated the number of galaxies in the Universe at 200 billion. But images from the Hubble telescope and data collected by ground-based observatories have shown us that, in reality, there are 10 times that number, or 2,000 billion galaxies...
While 90% of galaxies have yet to be studied, astronomers have been able to identify groups of galaxies, such as the Local Group, to which the Milky Way belongs. The Local Group itself is part of the Virgo Supercluster, an immense cluster of galaxies. At the center of the Virgo Supercluster lies the Virgo Cluster.
Located at the heart of the Virgo Constellation, the Virgo Cluster has fascinated scientists since its discovery by French astronomer Charles Messier in 1781. It is thought to contain up to 2,000 galaxies, 90% of which are dwarf galaxies. That's 50 times more galaxies than the Local Group!
The Virgo Cluster is the largest grouping of galaxies in the nearby Universe. For this reason, it is of particular interest to astronomers who are seeking to count all the galaxies in the observable Universe. Let's set off to discover this neighboring group of galaxies, located at the center of the Virgo supercluster.
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💥 The Mysteries of the Virgo Cluster:
- The Virgo Cluster was discovered in 1781, by French astronomer Charles Messier. Charles Messier was not only an outstanding astronomer, he was also a renowned comet hunter. Today, he is best known for creating the catalog of nebulae and star clusters known as the Messier Catalogue. This catalog lists objects of diffuse appearance, and was created to help comet hunters avoid confusing these objects with comets! These diffuse objects are in fact galaxies, nebulae and star clusters, even if we didn't know it at the time.
The objects in Messier's catalog are marked with a capital M followed by a number, ranging from 1 to 110. If you've been following along, you'll have understood that M87, M86 and M49, the galaxies that form the three main sub-clusters of the Virgo cluster, are part of this catalog.
Charles Messier mapped many of the galaxies in the Virgo cluster, including M87, M86 and M49, as well as M58, M59, M60, M61, M84, M85, M88, M89, M90, M91, M98, M99 and M100. Most of the galaxies in the Virgo Cluster were discovered between 1770 and 1780, and were initially thought to be nebulae. It wasn't until the 1920s that it became clear that they were galaxies.
By the end of the 20th century, photographs had revealed between 1,500 and 2,000 galaxies in the Virgo Cluster, between 50 and 70 million light-years away. Between 2008 and 2012, the NGVS (Next Generation Virgo Cluster Survey) project was carried out to image the Virgo cluster and perhaps discover other galaxies. The project involved the CFHT's 3.5-metre telescope, the Canada France Hawaii Telescope, and a team of 45 members from universities and research institutes in Europe and North America. Because the Constellation Virgo is only observed in spring and winter, this project has lasted several years, and the results are still being interpreted. But we have no doubt that it will gradually reveal an unsuspected number of new galaxies!
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🎬 Today's program:
- 00:00 - Introduction
- 03:35 - Journey to the Virgo Cluster
- 07:31 - The Virgo Constellation
- 10:28 - The Constellation of Berenice's Hair
- 11:56 - Discovery of the Virgo Cluster
- 15:40 - Journey to the Virgo Supercluster
- 17:18 - How was the Virgo Cluster formed?
- 20:14 - The structure of the Virgo Cluster
- 26:32 - Composition of the Virgo Cluster
- 30:59 - The galaxies of the Virgo Cluster
- 33:00 - Different types of galaxies
- 42:38 - M87
- 53:24 - M86
- 01:01:02 - M49
- 01:06:43 - Other notable galaxies
- 01:10:05 - Discovering the stars of the Virgo Cluster
- 01:17:45 - Other notable objects in the Virgo Cluster
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15 июн 2024
