Milky Way

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Introduction1

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The latest star map from the Gaia spacecraft plots 1.7 billion stars (Lisa Grossman, Science News)

Dictionary

Milky Way : the galaxy of which the sun and the solar system are a part and which contains the myriads of stars that create the light of the Milky Way — Webster

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Encyclopedia

Milky Way is the galaxy that contains our Solar System. The descriptor “milky” is derived from the galaxy’s appearance from Earth: a band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe. Following the 1920 Great Debate between the astronomers Harlow Shapley and Heber Curtis, observations by Edwin Hubble showed that the Milky Way is just one of many galaxies.

The Milky Way is a barred spiral galaxy with a diameter between 150,000 and 200,000 light-years (ly). It is estimated to contain 100–400 billion stars. There are probably at least 100 billion planets in the Milky Way. The Solar System is located within the disk, 26,490 (± 100) light-years from the Galactic Center, on the inner edge of the Orion Arm, one of the spiral-shaped concentrations of gas and dust. The stars in the innermost 10,000 light-years form a bulge and one or more bars that radiate from the bulge. The galactic center is an intense radio source known as Sagittarius A*, likely a supermassive black hole of 4.100 (± 0.034) million solar masses.

Stars and gases at a wide range of distances from the Galactic Center orbit at approximately 220 kilometers per second. The constant rotation speed contradicts the laws of Keplerian dynamics and suggests that much of the mass of the Milky Way does not emit or absorb electromagnetic radiation. This mass has been termed “dark matter”. The rotational period is about 240 million years at the position of the Sun. The Milky Way as a whole is moving at a velocity of approximately 600 km per second with respect to extragalactic frames of reference. The oldest stars in the Milky Way are nearly as old as the Universe itself and thus probably formed shortly after the Dark Ages of the Big Bang.

The Milky Way has several satellite galaxies and is part of the Local Group of galaxies, which form part of the Virgo Supercluster, which is itself a component of the Laniakea Supercluster. — Wikipedia

Encyclopædia Britannica

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Note: This is a 360° Video — press and hold to explore it!

This 360-degree movie immerses viewers into a simulation of the center of our Galaxy. This visualization was enabled by data from Chandra and other telescopes and allows viewers to control their own exploration of this region. From the vantage point of the Milky Way’s supermassive black hole, Sgr A*, the viewer can see about 25 Wolf-Rayet stars (white, twinkling objects) as they continuously eject stellar winds (black to red to yellow color scale). These winds collide with each other, and then some of this material (yellow blobs) spirals towards Sgr A*. The movie shows two simulations, each of which start around 350 years in the past and span 500 years. The first simulation shows Sgr A* in a calm state, while the second contains a more violent Sgr A* that is expelling its own material, thereby turning off the accretion of clumped material (yellow blobs) that is so prominent in the first portion.

Our Galactic Core Has Thousands of Black Holes (Daniel Starkey, Geek.com)
New Study Suggests Tens of Thousands of Black Holes Exist in Milky Way’s Center (Jessica Guenzel, Columbia News)

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The Milky Way (Ask an Astronomer, Cornell University)
Milky Way (Cosmos4Kids)

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More News …

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  • Gaia could detect free-floating black holes...
    on June 28, 2022 at 1:06 pm

    The thing with black holes is they're hard to see. Typically we can only detect their presence when we can detect their gravitational pull. And if there are rogue black holes simply traveling throughout the galaxy and not tied to another luminous astronomical, it would be fiendishly hard to detect them. But now we have a new potential data set to do so.

  • Studying galaxy growth spurts in the early...
    on June 27, 2022 at 9:03 pm

    In the American Wild West, high noon was a time for duels and showdowns. When it comes to the history of the universe, cosmic noon featured fireworks of a different sort. Some 2 to 3 billion years after the big bang most galaxies went through a growth spurt, forming stars at a rate hundreds of times higher than we see in our own galaxy, the Milky Way, today. When it launches by May 2027, NASA's Nancy Grace Roman Space Telescope promises to bring new insights into the heyday of star formation.

  • VY Canis Majoris is dying, and astronomers are...
    on June 27, 2022 at 1:46 pm

    Three-dimensional models of astronomical objects can be ridiculously complex. They can range from black holes that light doesn't even escape to the literal size of the universe and everything in between. But not every object has received the attention needed to develop a complete model of it, but we can officially add another highly complex model to our lists. Astronomers at the University of Arizona have developed a model of VY Canis Majoris, a red hypergiant that is quite possibly the largest […]

  • Astronomers find imprint of the bubbles produced...
    on June 24, 2022 at 2:31 pm

    An international group of astronomers, led by Juan Diego Soler of the Italian National Institute for Astrophysics (INAF), have found the imprint of the bubbles produced by the explosion of dying stars in the structure of the gas that pervades our galaxy. They made this discovery by applying techniques from artificial intelligence to the HI4PI survey data, which provides the most detailed whole-sky distribution of atomic hydrogen in the Milky Way to date. The scientists analyzed the filamentary […]

  • Image: Hubble snaps globular cluster Terzan 9
    on June 21, 2022 at 1:06 pm

    This star-studded image shows the globular cluster Terzan 9 in the constellation Sagittarius, toward the center of the Milky Way. The NASA/ESA Hubble Space Telescope captured this glittering scene using its Wide Field Camera 3 and Advanced Camera for Surveys.

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Adventures

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Related

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Knowledge Realm

Physical

“Fundamentals”
Law (Constant) Relativity
Force Gravity, Electromagnetism (Light, Color)
Matter (Microscope) Molecule, Atom (Periodic Table), Particle

“Space”
Universe (Astronomical Instrument)
Galaxy Milky Way, Andromeda
Planetary System Star, Brown Dwarf, Planet, Moon

Our Neighborhood
Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Trans-Neptunian Object
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid

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Notes

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