# ISS Eclipse Determination

Determining eclipses is crucial in designing space missions. Satellites need to account for periods of complete darkness where they receive no solar radiation. Eclipses consist of the Umbra (complete darkness), Penumbra (varying darkness), and full sunlight. Higher altitude orbits spend more time in the Penumbra. To determine eclipses, knowledge of position vectors and radii is required. The ISS, with its low orbit, is less affected by the Penumbra. The Julia Package SatelliteToolbox.jl simplifies the process of converting Two-Line Elements (TLE) into orbits. The TLE provides mean motion, which helps calculate the time required for one orbit. Trigonometry and vector math are used to determine if the ISS is in the penumbra or umbra. The sunlight function calculates the fraction of light received. The ISS spends approximately 62% of its time in sunlight, with minimal time in the penumbra.

This content was originally posted on my projects website here. The above summary was made by the Kagi Summarizer