Venus, like other planets in our solar system, goes through a series of positions and phases as it orbits the Sun. The change to the eastern elongation (sunrise) for Venus in August occurs due to its specific orbital dynamics and the relative positions of Venus, Earth, and the Sun.
Here's a breakdown of the phenomenon:
Orbital Motion: Venus orbits the Sun in an inner orbit compared to Earth, completing one orbit in about 225 Earth days. As a result, Venus goes through different phases as observed from Earth, similar to the phases of the Moon.
Inferior Conjunction: When Venus is on the opposite side of the Sun from Earth, it is in a position known as inferior conjunction. At this point, Venus is not visible to us because it is obscured by the Sun's glare.
Morning Elongation: As Venus moves away from the Sun in its orbit, it eventually reaches a position where it appears to be farthest from the Sun as observed from Earth. This is known as the eastern elongation or the morning elongation. During this phase, Venus rises in the morning sky before the Sun, hence the term "sunrise elongation."
Timing in August: The specific timing of Venus' eastern elongation in August is a result of the combined motions of Venus and Earth in their respective orbits. The length of Venus' orbital period and Earth's orbital period, along with their relative positions, determine when Venus reaches its eastern elongation.
It's worth noting that Venus does not always reach its eastern elongation in August. The timing can vary from year to year. The orbital periods of Venus and Earth, combined with their relative positions, result in a different timing for each elongation.
In summary, Venus changes to the eastern elongation (sunrise) in August due to its orbital motion and the relative positions of Venus, Earth, and the Sun. This phenomenon occurs when Venus reaches its farthest point from the Sun as observed from Earth and rises before the Sun in the morning sky.