Scientists shows that there are couple of ways to measure a day on Earth...We use the longer one...
How long does it take the Earth to rotate 360 degree? Not 24 hours, it turns out that's exactly 23 hours 56 minutes and 4 seconds.
But because the Earth is rotating again and again or constantly rotating with its orbit around the Sun, a different point on the planet faces the Sun directly at the end of the 360 degree spin.
To reach exactly on the same position in the sky, the Earth has to rotate 1 degree further.
This is how the human has chosen to measure the days: not from the exact rotation of the Earth, but from the position of the Sun in the sky.
Technically, these are two different types of daylight. The day, measured by the completion of a 360 degree rotation, is called sidereal day.
A day is however, a solar day, depending on the position of the Sun. The latter is four minutes longer than the former, even the 24 hour we used.
'' It's only because we rotate in an orbit of the sun, which takes 24 hours on a solar day,'' James O. Donoghue, A planetary scientist at the Japanese Space Agency ( JAXA ), told business insider.
'' If we did not revolve around the Sun, both days would be the same.''
There are some images for you to understand better and easily.
Because we go through solar days in our calendar, we count 365 day in one year. But the Earth actually completes a full rotation ( one sidereal day ) 366 times per year.
James O. Donoghue a Japanese space Agency's planetary scientist describe the difference between these two types of day as a matter of choosing which background abject we use as a basis of comparison for rotation of Earth. A full rotation relative to the position of the Sun is a solar day. A full rotation relative to all the other Stars we see is a sidereal day.
If we use the day instead,'' every day about four minutes before the Sun will rise,'' James O. Donoghue said. '' Six month after doing so, the Sun will rise 12 hours earlier.'' He also said that '' we have decided to relate our daily rhythm to the Sun and not to the stars. In fact, the Stars rise about four minutes earlier each day because of our choice.''
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