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Heliacal rising
The heliacal rising of a star (or other body such as the moon or a planet) occurs when it first becomes visible above the eastern horizon at dawn, after a period when it was hidden below the horizon or when it was just above the horizon but hidden by the brightness of the sun. Each day after the heliacal rising, the star will appear to rise slightly earlier and remain in the sky longer before it is hidden by the sun (the sun appears to drift eastward relative to the stars along a path called the ecliptic).
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