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Gallery 3 > astroscapes (The Night Sky) > Chapter 5
01. Terris Novalis, Consett, County Durham
02. Terris Novalis, Consett, County Durham
03. Groverake Mine, Weardale, County Durham
04. Groverake Mine, Weardale, County Durham
17. ISS Fly By, Cawfields Quarry, Cumbria
18. Star Trails, RAF Spadeadam, Gilsland, Cumbria
19. Polaris, RAF Spadeadam, Gilsland, Cumbria
20. Lockheed Shooting Star (plus one), RAF Spadeadam
13. Earth Rotation, Derwentwater, Lake District
14. Milky Way Rising, Derwentwater, Lake District
15. Purple Haze, Derwentwater, Lake District
16. Comet Trails @ Cawfields Quarry, Cumbria
09. Lilburn Tower, Northumberland
10. Dunstanburgh Castle, Northumberland
11. Stranger Within, Holy Island Boat Huts
12. Cosmic Causeway, Holy Island, Northumberland
05. Full Worm Moon, Ludworth Tower, County Durham
06. A Spider On The Wall, Ludworth Tower
07. Star Trails Over Ludworth Tower, County Durham
08. Dunstanburgh Castle, Northumberland
21. The Wing Man, RAF Spadeadam, Cumbria
22. Seeing Double, RAF Spadeadam, Cumbria
23. Battle-SCAR Galactica, RAF Spadeadam, Cumbria
24. Tommy, The Star Of The Show
Aurora Borealis (Northern Lights)
If you have ever seen an aurora light up the night sky with its shifting waterfall of colors, you've seen one of the most amazing shows nature can offer. What causes an aurora? When charged particles from the magnetosphere collide with atoms in the earth's upper atmosphere, they absorb extra energy that is expressed as light. As the sun causes hydrogen and helium to fuse, protons and electrons are shot into space. Known as the solar wind, this stream of particles blows past the earth. As they blow past the earth, the earth's lines of magnetism draw the particles toward the north and south magnetic poles, where these lines converge. When the particles arrive in the ionosphere, they collide with gas atoms and emit light. The color of light they emit depends upon the type of gas the particles collide with. Light that is dominated by emissions from atomic oxygen causes a greenish and dark-red glow. Blue light is a result of atomic nitrogen, while purple light is the result of molecular nitrogen. Many other colors can also be seen.
Not to be confused with the chocolate bar produced by the Mars company (wink). The Milky Way is the galaxy that contains our Solar System. Its name "milky" is derived from its appearance as a dim glowing band arching across the night sky whose individual stars cannot be distinguished by the naked eye. The term "Milky Way" is a translation of the Latin via lactea, from the Greek (galaxías kýklos, "milky circle"). 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—now estimated to number as many as 200 billion galaxies in the observable universe.
The Milky Way is a barred spiral galaxy that has a diameter usually considered to be about 100,000–120,000 light-years but may be 150,000–180,000 light-years. The Milky Way is estimated to contain 200–400 billion stars, although this number may be as high as one trillion. There are probably at least 100 billion planets in the Milky Way. The Solar System is located within the disk, about 27,000 light-years from the Galactic Center, on the inner edge of one of the spiral-shaped concentrations of gas and dust called the Orion Arm. The very center is marked by an intense radio source, named Sagittarius A*, which is likely to be a supermassive black hole.
Capturing Star Trail Images
Star trail photographs are captured by placing a camera on a tripod, pointing the lens toward the sky, and allowing the shutter to stay open for a long period of time. Star trails are considered relatively easy for amateur astrophotographers to create. Photographers generally make these images by using a SLR camera with its lens focus set to infinity. A cable release allows the photographer to hold the shutter open for the desired amount of time. Typical exposure times begin at 15 minutes and can be many hours long, depending on the desired length of the star trail streaks on the image. Even though star trail pictures are created under low-light conditions, the long exposure times allow for fast films, such as ISO 200 and ISO 400, to be used. Wide-apertures, such as f/5.6 and f/4, are recommended for star trails.
Because exposure times for star trail photographs can be several hours long, camera batteries can be easily depleted. Mechanical cameras that do not require a battery to open and close the shutter have an advantage over more modern film and digital cameras which utilize battery power. On these cameras, the Bulb, or B, exposure setting is used to keep the shutter open. My star trail images are made by taking a time exposure of about 10 to 15 minutes. However, with modern digital cameras, 30 seconds is about the longest exposure possible, due to electronic detector noise effectively snowing out the image. To achieve the longer exposures I do what many amateur photographers do. I take multiple 30-second exposures, then 'stack' them using imaging software, thus producing the completed star trail image.
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