130803 - Milky Way Nucleus @ FM1398 near Blackburn Dam
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click image to enlarge
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ASTRO:
type=Barred Spiral galaxy (Milky Way nucleus) const=Sagittarius-Scorpio mag=-20.9 (integrated) dist=27k ly size=185k ly IMAGE: location=FM1398 near Blackburn Dam on Lake Palestine, TX BrtlCls=4 moon=9% WnCr exposure=DSLR OSC: 1x30s, f/3.5, ISO6400 EQUIPMENT: camera=Nikon D90 (stk) optics=NIKKOR 18-105mm DX kit zoom lens @ 18mm filter=(none) mount=simple tripod guiding=(none) SOFTWARE: acquisition=(in-camera) processing=PhotoshopCC |
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Our home galaxy, the Milky Way is classified as a "barred" spiral galaxy with an estimated visible diameter of appx 185,000 light-years. It varies in thickness from appx 4000 light years at its central bulge (shown here) to about 1000 light years at the outer rims of its spiral arms. It is estimated to contain somewhere between 100 and 150 billion stars, and at least as many planets. Our Solar System is located at a radius of about 27,000 light-years from the Galactic Nucleus (or center) of the galaxy, on the inner edge of the Orion Arm, one of the spiral-shaped arms of concentrated gas and dust.
If one can imagine a "traditional" appearance of a galaxy, the Milky Way's stars in the innermost 10,000 light-year diameter form a bulge with a bar-like structure that rotates in a circular motion, with spiral-like formations radiating outward from the bulge. But because of our vantage point from here on Earth, the galaxy appears "on-edge", making our views look more like that of a dinner plate turned on-edge to our viewing angle. Much of the structure of the galaxy is obscured from our view because of heavy concentrations of galactic clouds of dust and gas.
To give some perspective on distances in space...
- the planet Mars when at its bi-annual closest encounter to Earth (a.k.a. "opposition") is appx 140 million (M) miles away. While traveling at an average speed of appx 24,600 mph (...faster that a typical muzzle velocity of a bullet), it took NASA's latest Mars probe, "Perseverance" appx 2-1/2 months to get there.
- it takes appx 9-1/2 minutes for radio signals (...traveling at the speed of light) to get from Perseverance on Mars back to Earth.
- the planetoid Pluto (the outermost planet-like body in our solar system) orbits our Sun at a mean distance of appx 3.7 billion miles, which approximates the radius of our solar system, and is equivalent to appx 4.5 light-hours away from us. In terms of its entire diameter, our solar system is 2x that distance, or appx 9 light-hours across. Working thru the math... that means our solar system is about 1/1000th of a light-year in diameter.
- Our Sun (...and hence, our Solar System) is located appx 27,000 light-years away from the galactic nucleus of the Milky Way, or appx 1/7th of the visible diameter of the galaxy.
- Or said another way, when we see the MW nucleus in our night sky tonight, we are seeing it as it existed 27,000 years ago. So when the light we see first began its trek toward us here on Earth, our ancestors were living in the late Stone Age, ...when they were painting petroglyphs on walls in caves, and carving and engraving images on bone or ivory.
The MW galactic nucleus is an intense source of radio waves known as "Sagittarius A". It was proven in 2022, through a technique called "radio photometry" to contain a supermassive black hole. That object is estimated to be 4.1 million times more massive than our Sun. Astrophysicists now believe that black holes exist at the centers of most galaxies found across the universe.
If one can imagine a "traditional" appearance of a galaxy, the Milky Way's stars in the innermost 10,000 light-year diameter form a bulge with a bar-like structure that rotates in a circular motion, with spiral-like formations radiating outward from the bulge. But because of our vantage point from here on Earth, the galaxy appears "on-edge", making our views look more like that of a dinner plate turned on-edge to our viewing angle. Much of the structure of the galaxy is obscured from our view because of heavy concentrations of galactic clouds of dust and gas.
To give some perspective on distances in space...
- the planet Mars when at its bi-annual closest encounter to Earth (a.k.a. "opposition") is appx 140 million (M) miles away. While traveling at an average speed of appx 24,600 mph (...faster that a typical muzzle velocity of a bullet), it took NASA's latest Mars probe, "Perseverance" appx 2-1/2 months to get there.
- it takes appx 9-1/2 minutes for radio signals (...traveling at the speed of light) to get from Perseverance on Mars back to Earth.
- the planetoid Pluto (the outermost planet-like body in our solar system) orbits our Sun at a mean distance of appx 3.7 billion miles, which approximates the radius of our solar system, and is equivalent to appx 4.5 light-hours away from us. In terms of its entire diameter, our solar system is 2x that distance, or appx 9 light-hours across. Working thru the math... that means our solar system is about 1/1000th of a light-year in diameter.
- Our Sun (...and hence, our Solar System) is located appx 27,000 light-years away from the galactic nucleus of the Milky Way, or appx 1/7th of the visible diameter of the galaxy.
- Or said another way, when we see the MW nucleus in our night sky tonight, we are seeing it as it existed 27,000 years ago. So when the light we see first began its trek toward us here on Earth, our ancestors were living in the late Stone Age, ...when they were painting petroglyphs on walls in caves, and carving and engraving images on bone or ivory.
The MW galactic nucleus is an intense source of radio waves known as "Sagittarius A". It was proven in 2022, through a technique called "radio photometry" to contain a supermassive black hole. That object is estimated to be 4.1 million times more massive than our Sun. Astrophysicists now believe that black holes exist at the centers of most galaxies found across the universe.