A conjunction is when two or more astronomical objects appear near one another in the sky.
This is the closest conjunction of Jupiter and the Moon until 2026. Not visible is the bright moon Europa which is directly in front of the planet Jupiter.
A celestial occultation is when one celestial body passes directly in front of another. On April 22, 2009 the waning moon passed in front of the planet venus in the morning twilight.
Throughout the year, the planets move across the sky in relation to other stars. It's not the star's aren't moving, it's that they are so far away, they don't appear to ever move from our location. We've been able to detect only slight changes in star locations over the 1000's of years of human observation. But the planets are very close, so it's easier to detect their movements. By the way, this is what perplexed early astronomers so much - how some 'stars' (really planets) moved and others didn't. What really drove them nuts was the fact that on rare occasion these 'stars' would slowly come to a stop in their motion across the night sky, reverse direction for a while, then start moving normally again.
This photo was also taken at a time when Mars appears motionless in the sky. Imagine being in a car race against one other driver on a circular racetrack. The other car stays in the outside lane, while you drive slightly faster in the inside lane. You will always move faster than the other car. If you always looked directly at the other car, it would always appear to be moving in one direction in relation to the distant background, except at a point when you are passing the car. In relation to the background, it would slowly come to a stop, move backward a little, come to another stop, then proceed forward as before. This same principle can be applied to outer planets as we overtake them in their orbits.
This animation demonstrates this very well. Click on the image to play it.
The beautiful conjunction of the Moon, Venus, and Mercury (from top to bottom) was captured from my front porch with a Nikon D70 and a Sigma 70-300 lens. The following photo was taken a few minutes later. Notice the Earthshine on the moon - light reflecting off of the Earth and back onto the moon, slightly illuminating it.
