An eye-catching conjunction of the Moon, Venus and Jupiter
The image shows a conjunction of the crescent Moon, Venus and Jupiter. Venus and Jupiter shine as bright, star-like objects. Venus is the brighter object, near the Moon. The photo was taken on 1 December 2008. 
 Photo by Aymen Ibrahem, Senior Astronomy Specialist
On the evening of 4 April 2010, the skies of Egypt will feature a fascinating spectacle: Venus and Mercury will be in conjunction. To the unaided eye, Mercury and Venus will be visible as bright star-like objects, shining close together, near the horizon, in the western sky. The angular (apparent) separation between the two planets will be only about 3 degrees. 

A conjunction is one of the most beautiful astronomical phenomena that can be viewed with the unaided eye. When at least two celestial bodies are close to the line of sight, they are said to be in conjunction.

Over the last week, Mercury, the innermost planet, was approaching Venus, the brightest and nearest planet to Earth. BA Senior Astronomy Specialist, Aymen Ibrahem, has monitored the motion of Mercury, relative to Venus, and recorded interesting images of the evening celestial showpiece.

Currently, Venus is approximately 235 million km away, while Mercury’s distance from Earth is approximately 149 million km. Therefore, the current distance of Mercury is similar to that of the Sun. The Earth-Sun distance is a small distance, by the cosmic distance scale, but a virtual trip by train, from Earth to the Sun, lasts over 170 years, if the train speed is 100 km/h. 

Venus and Mercury are termed inferior planets, as they are both closer to the Sun than Earth. To view the conjunction, begin observing about 40 minutes after sunset. The conjunction will be visible low in the sky, close to the direction of west. Therefore, the horizon of the observing site must be clear, not obscured by terrains or high buildings. In most of Alexandria, the seashore is a good observing location, where the western horizon is clear. The direction of west can be found by compass. In Alexandria, Egypt, the conjunction can be spotted in the direction opposite to that of the city of Mecca.

An inferior planet can only be viewed in the evening, after sunset, or in the morning, before sunrise, as the inferior planets are always close to the Sun, in the sky. Mercury is usually difficult to observe, due to its proximity to the Sun. The best time to observe Mercury is when the planet reaches its maximum angular distance from the Sun.