![]() The term Analemma comes from Greek and refers to the pedestal of a Sundial. This is because the position of the Sun in the sky depends not only on the shape of the planet’s orbit around it, but also on the angle of the planet’s rotational axis. The Analemma for the Sun has different shapes on each of the 8 planets. In addition, the direction of the Analemma also differs depending on the observers location on Earth, Observers at the North Pole will see only the top loop of the Analemma, while those at the South Pole will observe only the bottom portion of their Analemma. This is opposite in the Southern Hemisphere, where the broader loop is on the top of the curve. In the Northern Hemisphere, the Analemma curve has the broader loop at the bottom. This has the effect of flattening out the bottom half of the curve.Įarth: The living planet Changes According to Location This means that one part of the orbital path (Perihelion) is closer to the Sun than the other (Aphelion).īecause of its orbital shape, the Earth moves faster around the Sun when it is at its Perihelion, around the Winter Solstice, than when it is at its Apehlion. Not only is the Earth’s orbital path elliptical, the Sun is not in the center of this path. If the Earth’s orbital path was circular, its axial tilt would have the effect of generating a perfect figure 8 Analemma curve, such that the top and the bottom loop would be the same size. At the equator, this line would be a straight line spanning from left to right or West to East. If the Earth’s orbital path was elliptical, but its axis not tilted, the Solar Analemma curve would be oval shaped. This effect is repeated similarly during the winter months to generate the second loop of the figure 8 curve. The top loop of the figure 8 Analemma is generated during the summer – as the summer months progress, the Sun moves further up on the sky, reaching the highest point around the summer solstice.įollowing the summer solstice, the apparent position of the Sun starts moving down the sky, generating the first loop of the figure. This has the effect of generating the two loops of the figure 8. The 23.4-degree axial tilt of the Earth affects the Sun’s apparent position in the sky – as the year progresses and the Earth continues to spin at a tilted axis and orbit around the Sun, the Sun seems to move up and down (North-South) in the sky. What is solar noon? Effect of the Axial Tilt These two factors combine to generate the figure 8 Analemma curve. Earth also revolves around the Sun on a slant it has an axial tilt of around 23.4 degrees. This is called the Sun’s Analemma curve.Įarth orbits around the Sun on an elliptical path. If you take a picture of the Sun from the same spot at the same time every day for a year, you will see that it follows the shape of a slightly oblong figure 8, with one loop broader than the other. If you take a picture of the Sun from the same spot at the same time every day for a year, it follows the shape of a slightly oblong figure 8. Business Date to Date (exclude holidays).
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