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Venus
(2013-12-26 17:27)


About this Object

Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has no natural satellite. It is named after the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of -4.6, bright enough to cast shadows in very dark locations. Because Venus is an inferior planet from Earth, its maximum elongation from the Sun is 47.8 degrees. Venus reaches its maximum brightness shortly before sunrise or shortly after sunset, for which reason it has been referred to by ancient cultures as the Morning Star or Evening Star. Venus is a terrestrial planet and is sometimes called Earth's 'sister planet' because of their similar size, gravity, and bulk composition.

About this Image

Compare this image to the image that I captured 11 days prior to this image. Visually, Venus is larger, but the crescent is thinner. Also compare the ephemeris associated with each image, and the data are there to back this up. From December 15th to the 26th, Venus moved 8 million miles closer to Earth, causing its apparent size to increase from 48 to 56 arcseconds in diameter, or about 20%. For comparison, the Sun and Moon are about 30 arcminutes, or about 1/2 of a degree in diameter. Also notice that as Venus continues on its orbit toward conjunction with the Sun, at point at which only the unlit side of Venus faces Earth, the portion of its surface that earthlings see as illuminated decreases from 18 to 8 percent. Venus' magnitude, which is a function of the size of the illuminated portion has decreased only slightly. I will prepare and post a drawing that illustrates these changes.


--- Date/Time ---
Local: 2013-12-26 17:27:00
UTC: 2013-12-26 21:27:00

--- Location ---
The Ashton Observatory at Johnson Farms, Ashton MD
(Latitude N39.15°, Longitude W77.01°, Elevation 510')

--- Conditions ---
Temperature: 33° Dew Point: 18° Humidity: 53% Marginal seeing

--- Optics ---
Televue NP101is 101mm f/5.35 Refractor with Televue 4x Powermate

--- Camera ---
Celestron NexImage 5

--- Selected Ephemeris ---
613.35 million miles from Earth and 755.42 million miles from the Sun
Apparent Diameter: 48.02 arcminutes. Magnitude: -2
Percent Illuminated: 99.91%. Elongation from Sun: 162.05°



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