The are varying numbers for the Venus distance from Earth. Each number depends on the relative position of each planet in its elliptical orbit. The point when the planets are at their closest approach to each other is called opposition. The distance between the planets can even vary at different oppositions. The closest possible opposition distance between Earth and Venus is 38 million kilometers. This is the closest that any planet comes to Earth.
The farthest that Venus ever gets from Earth is 261 million km. The means that the Venus distance from Earth can vary by an incredible 223 million km. While that seems like an amazing distance, it is nothing compared to the numbers attributed to other planets. Try to imagine how far it is between Earth and Neptune. Here is a link that tells you how to figure those distances out.
The relative proximity of Venus helps to explain why it is the second brightest object in the night sky. The planet has an apparent magnitude of about -4.9 at its brightest. It can also completely disappear from the night sky when it is at its most distant, because the Sun is between it and the Earth. The planet’s apparent magnitude is also helped by the reflectivity of the sulfuric acid clouds that dominate its atmosphere. The clouds reflect a great deal of visible light, increasing the planet’s albedo and making it more readily seen.
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Venus will periodically pass across the face of the sun. This is called a transit. These transits of Venus occur in pairs with more than a century separating each pair. Since the advent of the telescope, transits have been observed in 1631, 1639; 1761, 1769; and 1874, 1882. the most recent occurred on June 8, 2004. The second in this pair will occur on June 6, 2012, so mark your calenders and prepare your telescopes. The planet can also be seen to go through phases much like the Moon when you observe it through powerful binoculars or small telescopes.
Venus is always brighter than any star. It is at its brightest when the Venus distance from Earth is the smallest. The planet can be easy to see when the Sun is low on the horizon, it always lies about 47° from the Sun. The planet orbits faster than the Earth, so overtakes it every 584 days. When this happens Venus is more easily seen in the morning, just after sunrise. Hopefully, you have found quite a bit of useful information here.
We’ve also recorded an entire episode of Astronomy Cast all about Venus. Listen here, Episode 50: Venus.