John Settle's

Urban Astro Images Web Site
Planetary Studies

Venus in 2002 as Viewed from Earth

Adapted from Sky & Telescope by Herman Heyn

With a telescope, we can watch Venus go through "Phases" like our moon. However, while the moon's phases  take 29.5 days to complete a full cycle, Venus' take 20 months. In 1543, Coperncus predicted that if the planets orbit the Sun, Venus would show phases like our Moon's. This was before the telescope, which was invented around 1602. Galileo's 1610 telescopic observation of Venus' phases was the first direct evidence of the correctness of Copernicus' theory.

Galileo's discovery was not the final proof that the planets go around the Sun. Tycho's system had the five planets revolving around the Sun, while the Sun revolved annually around the Earth. Earth stood still and Venus showed phases in Tycho's system. The final proof of Copernicus had to wait until Bessel's detection in 1839 of the parallax effect in a "fixed" star (61 Cygni). Copernicus predicted the parallax effect but assumed the stars were too distant for it to be observed.

At "Inferior Conjunction" Venus passes from the evening sky into the morning sky; changing from the "Evening Star" to the "Morning Star."

Venus at Inferior Conjunction

 
Photo by Lyn Miller

Conjunction is the alignment of two solar system objects so that, seen from earth, they have the same longitude. For planets, this alignment is with the sun and a planet. The planets closer to the sun than the earth are called inferior planets. The planets farther away from the sun than earth are called superior planets. A superior planet is said to be in conjunction when it is on the other side of the sun as seen from earth. An inferior planet can be in superior or inferior conjunction. Superior conjunction occurs when the planet is on the other side of the sun as seen from earth. Inferior conjunction occurs when planet is between the sun and the earth. The moon is at conjunction when it is between the earth and the sun.

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Planetary Images

Jupiter 02/02/2002 by David Corum

On the Left is David's Original Image / On the Right is Same Processed with Real Unsharp Masking Technique

David writes: "John, Pix of Jupiter was taken Feb. 2, 2002, from Little Bennett Regional Park, in Montgomery County. I was using a 9.25" Celestron SCT and a 5x Televue Powermate barlow, OM-1 camera,Kodak E200 film, 1/2 sec. exposure.That night, the sky was incredibly stable for this area (8/10) although the transparency was lousy. It's ironic that I was lying on my back amidst scattered horse manure while taking this picture.(I found out about the horse manure at home after my coat warmed up. My wife was not impressed.)"

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Ron Lee Captured this Image of Jupiter and three moons using a Nikon 990 Digital Camera Afocally

Ron Also Did Saturn the same.

Memory considerations do not allow me to do justice to the original image.

Both frames were taken on the night of 12/26/2001 using an 8" f/10 SCT(Meade LX90) and an 8 mm. (Radian) eyepiece. A Nikon 990 digital camera was coupled afocally (see, e.g., Michael Covington, "Astrophotography for the Amateur") to the eyepiece using TeleVue's camera/eyepiece adapter for the Radian. The Nikon was used in the Fine 3:2 quality mode and recorded 2,048 x 1,360 pixel JPEG files from the 1/1.8" CCD. (In future, I will tend to use the HI quality mode that records TIFF files to eliminate compression losses of detail.) The built-in zoom on the Nikon worked very well and there was little to choose between fixing the focus at infinity and utilizing the camera's autofocus capability. The Saturn picture was taken at ~24 mm. and the Jupiter at ~8 mm. for projection magnifications of 3x (f/30) and 1x (f/10), respectively. The effective film speed was ISO 100 and the exposures were a trade-off between aperture and shutter speed.

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Reprocessed Saturn

Ed and I worked with Ron Lee's Saturn image above to see if we could bring out more detail. I put the image through the "Real" Digital Unsharp Masking process as detailed at www.astropix.com . After masking I did a histogram stretch to remove some of the green. Ed increased the brightness  to compensate for contrast loss in the "Real" Unsharp Masking process and applied some Photoshop Unsharp Masking.  What is you opinion? Drop us a line at Alpha Siderius and let us know if we helped the image or not.

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