Iridium Project is the name of a global telecommunication service using artificial satellites. We can make and receive a call wherever we are on the Earth using a special handheld phone. It's a great service but very costly because 66 satellites always have to be maintained. The project company once went bankrupt and it is run by a company different from the original one. If I sail across the Pacific Ocean in the future, I may use it, but usual people would never use it because of its high cost. I found an interesting iPhone application named "Iridium Flares." The 66 Iridium satellites sometimes reflects the sunlight and it looks like a flare. This application tells us the accurate date and time, direction and height, intensity of light and the name of the satellite. As I was staying up all nights, I could try and find the flare this morning. It was about a ten-second flare, but how interesting it is to see the flare just on the time and in the direction as predicted! Different from other astronomical events such as eclipses, the flares can be seen almost every day. I'm thinking about watching them as many as possible.
At the entrance of my garage, I looked up at the sky and found this beautiful scene. There was the Venus by the moon which was so bright that it wasn't extinguished by the light of the moon, the evening glow and even the outdoor light of the entrance. This is the typical brightness of the evening star. The star is as large as the earth, but is located way further than the moon. Have you thought about the reason why the evening star is so bright? The answer is simple when thinking about the orbit of the Venus and the Earth in the solar system. The Venus revolves around the sun on the inner orbit of the earth and therefore it cannot be away from the sun when looking at from on the earth. It means that the star can only be seen with the sun and it cannot be seen in the midnight because the sun and the Venus are at the opposite side of the midnight sky. It is always located around the sun and it can only be seen when the brightness of the Venus becomes stronger than the sun. That is the reason for the evening and morning star's brightness.