29. februar Letterbox Hybrid

29. februar je 60. dan v gregorijanskem koledarju in se pojavi le na prestopna leta.

February 29 is 60th day in Gregorian calendar and it shows only on leap year.

Prestopno leto imenujemo leto s 366 dnevi, v katerem je tudi 29. februar. 

Leto je prestopno, če je deljivo s 4 ob upoštevanju naslednjih pravil:

1. v primeru, da je leto deljivo s 100, leto ni prestopno
2. v primeru, da je leto deljivo s 400, leto je prestopno, ne glede na pravilo 1

Prestopna leta so v koledar uvedli zato, da se koledarsko leto ves čas ujema z letnimi časi. Letni časi se na Zemlji ponavljajo vsako tropsko leto; to je čas, ki ga Zemlja potrebuje, da zaključi tirnico po orbiti okoli Sonca. Obhodni čas Zemlje je približno 365,2422 dni, torej bi se letni časi počasi zamikali, če bi uporabljali le preprost koledar s 365 dni. Z zgoraj opisanim občasnim dodajanjem dneva februarju dobimo v gregorijanskem koledarju v povprečju 365,2425 dni na leto, kar pomeni, da ta koledar v 4.000 letih zamuja pol dneva.

Za vpis v dnevnik bo na terenu treba rešiti nalogo. Navodila so na zadnji strani ptičje hišice. Vrni jih na svoje mesto. Ne odpiraj na silo. Žig je del zaklada in ni namenjen menjavi. 

Leap year is a year with 366 days in which occurs Fevruary 29. Leap year is a year divisible by 4 with respecting following rules:

1. in case that a year is divisible by 100 it is not a leap year
2. in case that a year is divisible by 400 it is a leap year, notwithstanding rule 1 

Although most modern calendar years have 365 days, a complete revolution around the Sun (one solar year) takes approximately 365 days and 6 hours. An extra 24 hours thus accumulates every four years, requiring that an extra calendar day be added to align the calendar with the sun's apparent position. Without the added day, the seasons would move back in the calendar, leading to confusion about when to undertake activities dependent on weather, ecology, or hours of daylight.

A solar year, however, is slightly shorter than 365 days and 6 hours (365.25 days). More precisely, the Earth completes its orbit around the Sun in 365 days, 5 hours, 49 minutes, and 16 seconds (365.2425 days).To compensate for this, three days are removed every 400 years. 

To log in a logbook you will have to solve a task on the field. Instructions are on the back side of the bird house. Return them on their position. Don't use force. Stamp is part of the cache and it is not for changing.

Ta geozaklad je postavil član Geocaching kluba Geosledec.
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