When we travel at night and look up at the sky, we usually see many stars rather than just one. However, when we focus on a particular star and observe it while traveling, it may appear as though we are only seeing one star at a time. There are a few reasons for this perception:
Brightness and Visibility: Stars vary in their brightness, and our ability to see them depends on their magnitude and the presence of light pollution. When we focus on a particular star while moving, other stars might appear fainter or get lost in the background light, making them less noticeable.
Angular Size: Stars are incredibly distant from Earth, and they appear as point sources of light. Due to their immense distance, stars have an extremely small angular size. As we move or change our viewing direction, the star we were initially focusing on may move out of our direct line of sight, making it seem as though we are only observing one star at a time.
Atmospheric Effects: Earth's atmosphere can cause stars to twinkle or scintillate, especially when viewed near the horizon. This twinkling effect is due to the turbulent nature of the atmosphere, which refracts the starlight in different directions. When we focus on one star while traveling, the atmospheric conditions might make it more noticeable or visually distinct compared to other stars.
It's important to note that these observations may vary depending on factors such as the level of light pollution, atmospheric conditions, and the speed and direction of travel. Additionally, if you are referring to seeing only one star during daylight travel, it is likely because the brightness of the Sun overwhelms the visibility of other stars in the sky.