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1.7. Earth movements

The movements of the Earth

We have already seen that the Universe is in constant motion. The galaxies away from each other, the sun moves within the Milky Way, the planets revolve around the sun and satellites around planets. Also, they all revolve around themselves.

The main movements of the Earth are two:

  • Movement rotation. The Earth rotates on itself, and it takes 24 hours to make one complete revolution. This movement causes the succession of days and nights.
  • Movement translation. The Earth revolves around the Sun in an elliptical orbit. It takes one year (365 days, 5 hours, 48 ​​minutes, and 45.16 seconds) to go around completely. This movement originates the seasons of the year.

These earth movements also have consequences for living beings, such as:

  • When trees lose their leaves when daylight hours decrease.
  • When the plants bloom and bear fruit according to the hours of light and temperature.
  • When the animals go into heat at certain times of the year so that their young are born in good weather.
  • When some animals migrate to other areas at certain times of the year to have a more favorable temperature.

All these movements between the Sun, the Earth and the Moon, produce the following phenomena:

Curiosity: leap years

Since the Earth takes almost 365 days and almost 1/4 of a day longer to go around the Sun, it is necessary to adjust the calendar every four years by adding one more day to the month of February, and those years are leap years, with 366 days. Leap years are those whose number is divisible by four.

But the translation of the Earth lasts a little less, 365 days, 5 hours, 48 ​​minutes and 45.16 seconds, so that each year it advances a little more than 11 minutes. Therefore, there are some exceptions to leap years. 

The year lasts 365, but those years whose number is divisible by four will be leap. Years that should be leap, but are multiples of 100, such as 1700, 1800, 1900, 2100, etc., will not be leap, except those that are multiples of 400, such as 1600, 2000, 2400, which will be leap .

According to this calendar, called the Gregorian calendar, the year lasts 365.2425 days, which is 0.000300926 days longer than the solar year, about 26 seconds, so it will be necessary to add a new day to the calendar every 3300 years.