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Hour Angle Formula:
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The Hour Angle of the Sun is the angular distance between the Sun's current position and its position at local solar noon, measured along the celestial equator. It represents the time that has passed since the Sun's transit of the local meridian.
The calculator uses the Hour Angle formula:
Where:
Explanation: The formula calculates the angular distance of the Sun from the local meridian, with positive values indicating time after meridian transit and negative values indicating time before transit.
Details: Calculating the hour angle is essential for celestial navigation, astronomical observations, solar energy applications, and determining the Sun's position for various scientific and practical purposes.
Tips: Enter Local Sidereal Time and Right Ascension in hours. Both values should be in decimal format. The result will be in degrees, with positive values indicating west of the meridian and negative values indicating east.
Q1: What is Local Sidereal Time?
A: Local Sidereal Time is the hour angle of the vernal equinox, representing the right ascension of objects currently on the local meridian.
Q2: How is Right Ascension measured?
A: Right Ascension is measured in hours, minutes, and seconds along the celestial equator from the vernal equinox, similar to longitude on Earth.
Q3: What does a zero hour angle mean?
A: A zero hour angle indicates that the Sun is on the local meridian, which corresponds to local solar noon.
Q4: Why multiply by 15 in the formula?
A: Since the Earth rotates 360 degrees in 24 hours, the rotation rate is 15 degrees per hour (360 ÷ 24 = 15).
Q5: How accurate is this calculation?
A: The calculation is mathematically precise, but accuracy depends on the precision of the input LST and RA values and proper accounting for atmospheric refraction.