Based on your description, the fast-moving object you observed in the night sky that later disappeared is likely a satellite. Satellites are man-made objects that orbit the Earth at various altitudes. They can reflect sunlight and appear as bright points of light moving across the sky.
Several factors contribute to the visibility of satellites:
Sunlight Reflection: Satellites can reflect sunlight, making them visible from the ground. When the angle between the satellite, the Sun, and the observer on Earth is just right, the satellite can appear quite bright.
Orbital Characteristics: Satellites follow predictable paths around the Earth. Some satellites orbit at lower altitudes and move faster, while others orbit at higher altitudes and move slower. The combination of speed and altitude affects how quickly a satellite moves across the sky.
Visibility Duration: The visibility of a satellite can vary depending on its position relative to the observer, the time of day, and the satellite's orbital characteristics. Sometimes, a satellite may disappear from view when it enters the Earth's shadow, causing it to no longer reflect sunlight.
It's worth noting that there are different types of satellites, including those used for communication, weather observation, and scientific research. Some satellites are part of satellite constellations, which consist of multiple satellites working together to provide global coverage for specific purposes like navigation or internet connectivity.
If you're curious about the specific satellite you saw, there are websites and smartphone apps that can help you identify satellites by providing real-time tracking and predictions of satellite passes in your location.