Satellites do not give off any light of their own. The light that you see is sunlight that is reflected by the satellite. For a satellite to be visible from the Earth, it must be lit by the sun, and must be bright enough to be seen against the sky glow. For this reason, satellite passes are only visible before sunrise, and after sunset. During this time the sky is dark enough for the satellite to stand out against background sky. Later at night, satellites are in the shadow of the Earth, and won’t be visible. Also, light pollution can make the sky brighter, and the satellites harder to see.?The magnitude (Mag) represents the brightness of the ISS. The lower the number, the brighter it will appear. The scale is logarithmic, so when the magnitude increases by 1, the object will be approximately 1.4 times brighter.?The bar graph represents the magnitude of the pass. 1 Bar represents magnitude 1.5. Each increment represents a 0.5 increase in magnitude, up to 10 bars which represents magnitude -3.0 and brighter.?The Altitude, also known as elevation, is the angle of the ISS above the horizon. Zero degrees being on the horizon, and 90 degrees directly overhead.?The Azimuth is a compass bearing.?The Max details of a pass is when the ISS is at it’s highest point in the sky.?The whole sky chart is made to be held above your head. The direction of east and west is the reverse of what you would expect when reading a map.?All the pass dates and times are shown using the timezone of the device. To see the correct date and time for a pass in a different timezone, change the timezone of the device.