Venus – Bright Object at Sunset

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Venus in the evening Sky – courtesy Stellarium

 Venus (the planet)  at Sunset

You may be wondering what very bright object appears on the western horizon near sunset. It’s not a star, satellite or airplane . It’s the planet Venus. Venus does not always appear at  sunset. It does not have a fixed location in the sky, the way the stars do, like Betelgeuse in Orion. This is because Venus is a member of our solar system, and because it is much closer  than the nearest star,  (beyond our star,  the Sun), and because it orbits the Sun just as the Earth orbits does,  we see Venus at different locations depending on our relative orbits. The orbit of Venus lies in the same plane as the 8 other planets (plus pluto 🙂 and the Sun. This edge-on line of this plane is shown in the illustration. This is the plane of the ecliptic.

This time of year, the ecliptic makes a very shallow slant to the evening horizon for sky watchers in Canada. In the Fall, the ecliptic  path is at a very low angle, and so Venus never gets far from the horizon.  It sets before night fall. See more at http://astrobob.areavoices.com/2010/08/27/venus-proves-that-beauty-can-be-elusive/

Location of Venus in our Sky =  Orbit of Venus

Venus is  the brightest planet, and about as far as it gets from the sun in the evening sky . Venus always appears close to the sun – either at sunset or at sunrise. This is because it is travelling in the inner orbit of the solar system. Venus is closer to the sun then we are. It is an ‘inferior” planet, as is Mercury. Planets, who orbit in an ellipse beyond our planet, Mars, Jupiter, Saturn, Uranus and Neptune are  called “superior” planets. Their orbits are superior to that of Earth.

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Venus reaches its greatest Eastern elongation . We are seeing it to the “left” of the Sun :

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Its  greatest angular distance from the Sun on the sky — for this year, 2013,   occurs on November 1, when it lies 47° east of the Sun. (See above – Eastern Elongation)

Appearance in our Night Sky

The planet grows brighter as it falls back toward the Sun in our sky, reaching its peak in early December. This “evening star” then shines at magnitude –4.9 — some 25 times brighter than the night sky’s brightest star, Sirius.

Venus will pass between the Sun and Earth in January and then quickly rise into view before dawn. It will remain the “morning star” until next September. After passing on the far side of the Sun, it will return to view after sunset as an “evening star” in December 2014 and stay there until the following summer. See Is Venus either a “morning star” or an “evening star” during certain times of the year

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Image Courtesy http://astrobob.areavoices.com/2010/08/27/venus-proves-that-beauty-can-be-elusive/

For more information on the path of the planets, you can read  Lecture 1 of the MVC Night Sky Conservation Astronomy Course

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