170916 Pegasus-Cepheus-Cassiopeia-Andromeda starscape
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ASTRO:
type=starscape view=Pegasus constellation other=note that the Andromeda Galaxy is visible IMAGE: location=Okie-Tex SP 2015 BrtlCls=1 exposure=DSLR OSC: 1x25s (0.4m), f/3.5, ISO3200 EQUIPMENT: camera=Nikon D90 (stk) optics=NIKKOR 18-105mm DX kit zoom @ 18mm filter=(none) mount=simple fixed tripod guiding=(none) SOFTWARE: acquisition=(in-camera) processing=Photoshop, LrC |
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The Milky Way galaxy is home to our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of cloud-like light seen in the night sky formed from stars that cannot be individually distinguished by the naked (unaided) eye. It is estimated the Milky Way contains between 100 and 150 billion stars, encompassing almost all of the stars we see in our nighttime skies.
Late in springtime, toward the northern extents of the Milky Way, the constellations of Pegasus (the Flying Horse) and Cepheus & Cassiopeia (mythological King & Queen of Ethiopia) and Andromeda (mythological Princess of Ethiopia who was saved from the sea monster Cetus by the Mighty Warrior, Perseus) occupy a large expanse of the sky. Pegasus is the largest constellation visible from the northern hemisphere. The perspective of this segment of sky is actually looking outward, away from the central core of the Milky Way galaxy. The image 'with constellation lines' (and DSO's - artificially added) brings forward the familiar star patterns in this area of our nighttime sky. One particular deep sky object (DSO) is of course, the familiar Andromeda Galaxy. If one can find the prominent square of bright stars comprising the body of 'The Big Horse', it is an easy star-hop to find Andromeda galaxy.
This image somewhat approximates what night vision through the unaided eye is like. Because of its poor color sensitivity at low light levels, the human eye sees virtually no color at night. This is because we are diurnal mammals (daytime dwelling), as opposed to nocturnal (nighttime dwelling). Certain animals, such as the nocturnal Great Horned owl, have a much higher sensitivity to light in their nighttime vision.
The area inside and to the back of the human eye that does the job of "seeing" is called the Retina. It primarily contains two (2) types of photoreceptor cells called, "Cones" and "Rods". Cones detect color in the daytime, but cannot detect faint light during nighttime at all. They are highly concentrated in the center of the retina. That area of the retina is called the "Fovea". There is a notable "blind spot" at nighttime where faint objects like nebulae, galaxies, and fainter stars "disappear" when viewed in a direct line-of-sight, or "straight-on". To help work-around the deficiency, astronomers use a technique called, "Averted Vision" to force their view slightly off-center from the object of interest, and use their peripheral vision slightly away from their direct line of sight. This exposes the object to the Rods in the retina, which are located just outside the fovea. Rods cannot detect color; but, they are more sensitive to faint light. They are also more sensitive to motion. So, an added technique is to allow one's eyes to slowly move around the object of interest, so-as to create a sense of motion to the Rods within the peripheral vision zone. With a little practice, one can employ these techniques with almost no effort, and improve the ability to see astronomical objects.
Using averted vision, the Andromeda Galaxy will "pop-out" to observers under moderately dark skies, and who are patient and allow their eyes to adjust to the dark, and do the work involved with night vision. It takes appx 20--30 minutes for one's eyes to fully adapt to dark skies.
Late in springtime, toward the northern extents of the Milky Way, the constellations of Pegasus (the Flying Horse) and Cepheus & Cassiopeia (mythological King & Queen of Ethiopia) and Andromeda (mythological Princess of Ethiopia who was saved from the sea monster Cetus by the Mighty Warrior, Perseus) occupy a large expanse of the sky. Pegasus is the largest constellation visible from the northern hemisphere. The perspective of this segment of sky is actually looking outward, away from the central core of the Milky Way galaxy. The image 'with constellation lines' (and DSO's - artificially added) brings forward the familiar star patterns in this area of our nighttime sky. One particular deep sky object (DSO) is of course, the familiar Andromeda Galaxy. If one can find the prominent square of bright stars comprising the body of 'The Big Horse', it is an easy star-hop to find Andromeda galaxy.
This image somewhat approximates what night vision through the unaided eye is like. Because of its poor color sensitivity at low light levels, the human eye sees virtually no color at night. This is because we are diurnal mammals (daytime dwelling), as opposed to nocturnal (nighttime dwelling). Certain animals, such as the nocturnal Great Horned owl, have a much higher sensitivity to light in their nighttime vision.
The area inside and to the back of the human eye that does the job of "seeing" is called the Retina. It primarily contains two (2) types of photoreceptor cells called, "Cones" and "Rods". Cones detect color in the daytime, but cannot detect faint light during nighttime at all. They are highly concentrated in the center of the retina. That area of the retina is called the "Fovea". There is a notable "blind spot" at nighttime where faint objects like nebulae, galaxies, and fainter stars "disappear" when viewed in a direct line-of-sight, or "straight-on". To help work-around the deficiency, astronomers use a technique called, "Averted Vision" to force their view slightly off-center from the object of interest, and use their peripheral vision slightly away from their direct line of sight. This exposes the object to the Rods in the retina, which are located just outside the fovea. Rods cannot detect color; but, they are more sensitive to faint light. They are also more sensitive to motion. So, an added technique is to allow one's eyes to slowly move around the object of interest, so-as to create a sense of motion to the Rods within the peripheral vision zone. With a little practice, one can employ these techniques with almost no effort, and improve the ability to see astronomical objects.
Using averted vision, the Andromeda Galaxy will "pop-out" to observers under moderately dark skies, and who are patient and allow their eyes to adjust to the dark, and do the work involved with night vision. It takes appx 20--30 minutes for one's eyes to fully adapt to dark skies.