Explain when there is a change in the length of a solar day.

Time interval between two successive transits of a given meridian by the mean sun is called mean solar day. It is generally close to 24 hours, or the length of a day. The length of the solar day keeps changing throughout the year.

Now, the change in the solar time occurs due to the combination of reasons like the eccentricity of the orbit, the varying speed of earth's motion around the sun, the apparent shift in sun's potions in the sky.

If the earth's rotation were to be reversed then the length of the solar day would decrease and the earth would rotate faster on its own axis with respect to the sun then compared to the stars.

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Each time the Earth rotates around once on its axis, it moves a small distance along the its orbit around the Sun. Earth, therefore, has to rotate through slightly more than 360 degrees for the sun to return to the apparent location in the sky. Thus, the interval of time between noon one day and noon the next day(a solar day) is slightly grater than one true rotation period(one sidereal day). Our planet takes 365 days to orbit the Sun, so the additional angle is 360/365 = 0.986 degrees. Because Earth is rotating a the rate of 15 degrees per hour, takes about 3.9 minutes to rotate through this angel., the solar day is 3.9 minutes longer then the sidereal day(i.e, 1 sidereal day is roughly 23h 56m long). So the solar day would decrease by 7.8 minutes.

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