The moon orbits the Earth and the Earth, along with the other planets in the solar system, orbit the sun. Any alignment of the objects in the night sky could be considered a chance event but we can predict them with astonishing accuracy.
On many occasions, objects will appear very close to each other in the sky during events known as conjunctions. And one such conjunction will occur between the moon and Venus on Sept. 8.
In the evening of the 8th, the moon will be just 3 days old -- a waxing crescent -- and appear low in the western sky just after sunset. Look to the east of the moon by less than half a degree to see Venus shining brightly.
The two objects look close in the sky but, in reality, the moon will be 380,812 kilometers from us while Venus will be a whopping 159.9 million kilometers away!
The pair will look great to the naked eye and binoculars will reveal a beautiful sight. They are also close enough to be seen together in the same field of view of a telescope and low power eyepiece. The pair won't be visible for long, however, as they will set soon after the sun, so a clear western horizon away from any obstructions like trees and buildings is essential.
Assuming uninterrupted views and clear skies, this conjunction will provide a great photographic opportunity for anyone wishing to try and capture the celestial couple.
A DSLR camera is ideal for the job, but it will either need to be fitted to a long focal length telephoto lens or to a short focal length telescope of about 500mm. Cameras can be fitted easily to telescopes with simple and cheap adapters that replace the lens. The adapter slots into the eyepiece holder of a telescope and effectively turns the telescope into a big telephoto lens. With the average size of a DSLR camera chip and the 500mm focal length lens/telescope the two objects should resolve nicely.
Exposure times will vary significantly with the aperture of the telescope and the sky conditions in your location, but limit exposure times to no more than 1 second otherwise the rotation of the Earth will cause the image to blur as the Moon and Venus seem to move during the exposure. If you are using a camera lens then set the aperture to one less than fully open, this offers compromise between allowing light in and giving a nicely sharp image. For either telescope or lens, keep the film speed low, to ensure fine lunar detail is captured.