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What are worlds beyond our galaxy like? The Universe that surrounds us still hasn't revealed its limits. While we now know the boundaries of our own Milky Way Galaxy, our contemporary measuring instruments are unable to tell us whether the Cosmos, for its part, is unlimited or not. However, at present, the observable part of the Universe seems to represent a sphere of 93 billion light years in diameter. It is estimated that the cosmological horizon is about 45 billion light years from Earth. Nevertheless, light emitted by distant objects is gradually reaching us. This hypothetical boundary is therefore dynamic and the observable Universe is getting longer over time.
Scientists, who have long considered our Galaxy to be the center of the Universe, now know that this is not the case. They have long understood that our Sun is only one star among many others. What's more, they've been able to establish that our Galaxy represents only a tiny fraction of the cosmic immensity, despite its somewhat astronomical dimensions, on a human scale. Indeed, our Galaxy alone measures almost a hundred thousand light-years in length and a thousand light-years in thickness. On the scale of the Universe, with its trillions of galaxies, it's a mere grain of sand in the desert.
The Milky Way, because our solar system is part of it and thus includes the objects closest to us, has been the focus of a considerable number of studies and observations.
If it has given us many of its secrets, it is obvious that new elements will be uncovered as technologies progress. But do you think you know everything about our Galaxy? Do you have any idea of what surrounds it? Do you think that in a sidereal space millions or even billions of light years away, the stars then present behave differently?
🔥 As a reminder, the videos are published on SUNDAYS at 6:00 PM.
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💥 Beyond the Milky Way:
- The Milky Way thus evolves in the Universe in the middle of an incalculable quantity of stars. However, it has been established that it is part of a set of galaxies known as the Local Group. This contains over 60 galaxies, mainly dwarf galaxies, all linked by common gravitational forces. However, this Local Group represents only a tiny part of an even larger cluster of galaxies, the Virgo supercluster, on whose periphery it lies. This supercluster comprises at least 100 galaxy groups and clusters, and could be close to 200 million light-years across. It itself belongs to an even more gigantic structure, the Laniakea supercluster. The latter, made up of over 100,000 galaxies and stretching over 520 million light-years, has not convinced all scientists. Indeed, some believe that the galaxies in the latter structure are not gravitationally bound and, as a result, these sub-groups should disperse over time. But back to the Local Group. Despite its small size, it's a well-stocked catalog. It includes virtually all galaxy types, except for giant elliptical galaxies, which cannot be present in such a small structure, so to speak, compared to our human size!
The size of the Local Group is approximately 10 million light-years across, and its total mass is estimated at 2,300 billion solar masses. The galaxies furthest from our solar system are around 5 million light-years apart. While it is home to mostly dwarf galaxies, it is also host to three large, massive galaxies: the Andromeda galaxy, probably the largest, the Triangulum galaxy, the smallest, and of course our own Galaxy.
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🎬 Today's program:
- 00:00 - Introduction
- 03:15 - The Milky Way - surprising facts
- 06:26 - The Local Group
- 09:10 - Environment near the Milky Way
- 16:56 - Birth of Andromeda
- 20:15 - The irregular Sagittarius dwarf galaxy
- 23:30 - IC10 galaxy
- 28:03 - Cadwell 51 Galaxy
- 31:37 - Phoenix Dwarf Galaxy
- 34:01 - Toucan Dwarf Galaxy
- 36:24 - Wolf-Lundmark-Melotte Galaxy
- 39:09 - Leo A Galaxy
- 41:39 - Supernova aftermath LMC N49
- 45:03 - High-speed clouds
- 50:00 - Galaxy HVC 127-41-330
- 53:32 - Prodigiously long black hole jet
- 55:58 - Perseus A, the giant galaxy
- 01:01:13 - Gravitational wave signal GW190814
- 01:04:32 - Quasar HE0450-2958
- 01:09:14 - What's next?
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