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- We think of galaxies as gigantic spiral disks containing trillions of individual stars.
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- The Sloan Digital Sky Survey has discovered dozens of Dwarf Galaxies that only contain a few hundred stars. The total number of candidates being studied orbiting our Milky Way Galaxy is 50. The Milky Way itself contains 100 billion stars.
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- Two of the largest dwarf galaxies can be seen with the naked eye. These are known as the Large and Small Megellanic Clouds.
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- One of the main reasons for studying these small faint dwarfs is to uncover the mystery of Dark Matter. The measurements to date calculate that there is 5 times more Dark Matter that Visible Matter in or around galaxies.
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- Current theories that there are particles that respond to gravity but do not respond to electromagnetic radiation, therefore “ Dark Matter”. These hypothetical particles are called WIMPS, Weakly Interactive Massive Particles.
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- Astronomers hope to detect these WIMPS thinking they will emit Gamma Rays, the highest energy electromagnetic radiation when the WIMP particles decay or annihilate each other.
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- The Dwarf Galaxies appear to have an even higher ratio of Dark Matter, 100 to 1000 times faint visible matter. This conclusion is made measuring the relative motion of these galaxies.
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- Dwarf Galaxies are the oldest galaxies . Their stars are more than 10 billion years old. The Universe is 13.8 billion years old.
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- Current theories for galaxy formation is that they start out as small dwarfs and merge into giant spirals. The Milky Way Galaxy is still merging with several smaller dwarf galaxies. In fact in 4 billion years from now we will be merging with the largest galaxy in our Local Group of Galaxies, the Andromeda Galaxy. You can also see that with the naked eye, in the north sky line some 20 degrees above the horizon.
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- To learn more as always astronomers want bigger, more powerful telescopes. They want to study the faintest dwarfs to better understand and even discover the source of Dark Matter.
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- With the naked eye on a good night you can see 3,600 stars in the night sky. If the Earth was inside 47 Tucanae, NGC104, Globular Custer you would see 570,000 stars with the naked eye.
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- There are 160 Globular Clusters in the Milky Way Galaxy. These star clusters are 12 billion years old, compared to our Sun and Solar System that is 5 billion years old.
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- Some of the Clusters are 330,000 light-years from the center of the Galaxy and they take a billion years to complete one orbit. The Earth and our Solar System take 220 years to complete one orbit about the Galaxy center.
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- To further illustrate the density of stars in these clusters, again, NGC104, you could see 10,000 1st Magnitude stars compared to the 29 that we can see. You could see 130,000 6th Magnitude stars compared to the 6,000 we can see. The night sky would be 20 times brighter than our night sky when there is a full moon.
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- Request these Reviews to learn more:
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- #1813 - Galactic storms, quakes and waves. Also list 4 other reviews.
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- #1760 - When and how did the first galaxies form. How do galaxies regulate star formation?
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- #13 - How to weigh a galaxy? The mass of the Milky Way inside the orbit of Earth is 1.9*10^41 kilograms. The total mass of the Milky Way is 3.9*10^41 kilograms
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- #1132 - Why don’t galaxies follow the laws of gravity? Thus the theory of Dark Matter.
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- #53 - The farthest galaxy in our Universe is traveling 98% the speed of light away from us.
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- #892 - How galaxies grow up.
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- #1585 - Andromeda and Milky Way Collision in 6.3 billion years.
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- #933 - Galaxy evolution. Most have a Blackhole at their center.
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----- 707-536-3272 ---------------------- Thursday, March 3, 2016 -----
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