How long years

Our calendar year is shorter than the tropical year by 0. So to correct approximately , we add 1 day every four years leap year. Thus, three calendar years are days long; the fourth calendar year is days long. But since the Julian calendar was 0.

Between 46 BC and AD, this accumulated error amounted to a total of: 0. In , Pope Gregory XIII reformed the calendar by specifying that all years divisible by 4 are to be leap years except for century years, which must be divisible by to be leap years. Now, in years:. The Gregorian calendar came into use in Roman Catholic countries in October when the seasons were brought back into step by eliminating 10 days from the calendar then in use.

Thursday, October 4, was followed by Friday, October 15 which caused some consternation among the populace, especially those with birthdays on the eliminated dates! Some British documents from the period before the British reform actually contain two dates, an old and a new.

In each century, one out of every four years is divisible by 4. Of the century years, only , , and are divisible by , leaving , , , , , , , , and that are not. Both are incorrect. The first could be salvaged by asking: How many years have you lived in this house?

How many years did you live in this house? Similarly, the second utterance should be either: How long have you lived in this house? How long did you live in this house?

Improve this answer. Michael Seifert Michael Seifert 1 1 gold badge 4 4 silver badges 6 6 bronze badges. Equally you could say How long have you worked for? WS2 WS2 1, 9 9 silver badges 10 10 bronze badges. Why is that considered a year? Well, days is about how long it takes for Earth to orbit all the way around the Sun one time.

A year is measured by how long it takes a planet to orbit around its star. Earth orbits around the Sun in approximately days. An Earth year is actually about days, plus approximately 6 hours. Read more about that here. All of the other planets in our solar system also orbit the Sun. So, how long is a year on those planets? If a bird lasts long enough, however, the probability of it dying in a given year may once again rise.

Common Terns reach old age after about 19 years, and their annual risk of dying then goes up. Life expectancy in birds is closely correlated with size -- the larger the species, the longer it is likely to live. But the relationship is far from exact. Some groups of birds tend to have long lives for their sizes, especially the Procellariiformes tubenoses -- albatrosses, shearwaters, and petrels and Charadriiformes shorebirds, gulls and terns, and auks.

Other groups, for instance titmice and chickadees, wrens, and game birds, are shorter-lived than their sizes would predict. Birds can be very long-lived in captivity. One Sulphur-crested Cockatoo a common Australian parrot made famous by the TV show "Baretta" lived most of his plus years in a zoo. In nature, the life-spans of these species are much shorter.

As luck would have it, however, the record for a European Starling in the wild, 20 years, is 3 years longer than for any starling captives. The table on the next page gives longevity records years-months of wild birds.

Small differences among these figures should not be taken too seriously. For one thing, they represent the upper end of a range -- and the range of any measurement is a statistic that almost always increases with the number of measurements. If, for instance, you record the heights of a random sample of 10 American women, and then of another sample of a million American women, both the tallest and the shortest woman are virtually certain to be in the larger sample. So the minimum life-spans of bird species that are frequently banded are more likely to be greater than those of species rarely banded, everything else being equal.

It seems likely, for example, that the short record for the Northern Shrike is simply a result of a low frequency of banding. At any rate, remember that with the exception of efforts that may later be corrected, the numbers on the list can only increase. Remember also that these figures are maximum recorded ages. While at one point the maximum record for the Purple Finch was 10 years it has since been extended to almost 12 , of 1, recoveries from 21, banded individuals, only I lived 10 years, 6 lived 8 years, and 18 lived 7 years.

All the remainder lived less than 7 years. In short, the maximum life-span is far longer than the median life-span the length of the life of the individual that lives longer than half the population and shorter than the other half , which in songbirds is usually only a year or two. Recent work on seabirds by ornithologist Ralph Schreiber of the Los Angeles County Museum indicates that dramatic increases in longevity records of seabirds can be expected as more data are gathered.