Telescope Observation
Although any telescope (or steadily-held binoculars) will allow the phases of Venus to be seen, the planet is a notoriously difficult one to observe, for three main reasons. Firstly, whenever the planet is visible (shortly before sunrise or after sunset) it is positioned at a low altitude (angle above the horizon) where it is immersed in haze and atmospheric turbulence, which adversely affects the quality of the image seen in the telescope. Consequently most telescopic observers prefer to view the planet in full daylight - when its altitude is much higher - taking special care to shield the Sun from view. Secondly, the planet's brilliance - although making it a very obvious and beautiful object to the naked-eye - causes a menacing glare when
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With patience, perseverance and considerable experience, detailed images of the planet can be obtained using CCD cameras and modified webcams (excellent examples of which can be seen at Damian Peach's website and on the ESA site). Although modern technology has allowed much detail to be resolved and captured electronically, many observers prefer to record their observations of the planet with more traditional sketches and drawings made at the eyepiece, a time-consuming but rewarding experience (see for example a selection of sketches produced by observers at the Astronomy Sketch of the Day website).
Apart from slight variations caused by light-scattering in the Earth's atmosphere, Venus normally appears white through telescopes. Its clouds are actually pale lemon-yellow but this can be difficult to discern because the coloration is subtle and is easily lost in the planet's …show more content…
In theory, Venus should appear exactly half-phase (phase = 0.50 or 50%) when it reaches greatest elongation, however it frequently does not because of eccentricities in the orbits of Venus and the Earth. Even when these eccentricities have been factored in, the date of the predicted dichotomy and that of the observed dichotomy often differ by up to several days; this is known as Schröter's effect (after the German astronomer Johann Schröter, who first noted the phenomenon in 1793). The date of dichotomy for evening elongations often occurs earlier than predicted, whilst that of morning elongations occurs later than predicted. The exact reason for the phenomenon is not known; some attribute it to the scattering of sunlight in Venus' atmosphere, others simply to errors in observation. It is however worth noting that the terminator normally appears straight for about four days in each
With patience, perseverance and considerable experience, detailed images of the planet can be obtained using CCD cameras and modified webcams (excellent examples of which can be seen at Damian Peach's website and on the ESA site). Although modern technology has allowed much detail to be resolved and captured electronically, many observers prefer to record their observations of the planet with more traditional sketches and drawings made at the eyepiece, a time-consuming but rewarding experience (see for example a selection of sketches produced by observers at the Astronomy Sketch of the Day website).
Apart from slight variations caused by light-scattering in the Earth's atmosphere, Venus normally appears white through telescopes. Its clouds are actually pale lemon-yellow but this can be difficult to discern because the coloration is subtle and is easily lost in the planet's …show more content…
In theory, Venus should appear exactly half-phase (phase = 0.50 or 50%) when it reaches greatest elongation, however it frequently does not because of eccentricities in the orbits of Venus and the Earth. Even when these eccentricities have been factored in, the date of the predicted dichotomy and that of the observed dichotomy often differ by up to several days; this is known as Schröter's effect (after the German astronomer Johann Schröter, who first noted the phenomenon in 1793). The date of dichotomy for evening elongations often occurs earlier than predicted, whilst that of morning elongations occurs later than predicted. The exact reason for the phenomenon is not known; some attribute it to the scattering of sunlight in Venus' atmosphere, others simply to errors in observation. It is however worth noting that the terminator normally appears straight for about four days in each