## Featured Research

from universities, journals, and other organizations

# The Y5K Bug? Hurdling The Leap Day Problem

Date:
February 28, 2000
Source:
American Institute of Physics -- Inside Science News Service
Summary:
Leap day is more than a novelty that comes once every four years. And even with the extra day to even out the calendar, we may be headed for trouble down the line. It's what one physicist calls the "Y5K" problem.

COLLEGE PARK, MD (February 25, 2000) – Leap day may simply seem like a novelty that comes once every four years, but without it, the seasons would quickly get out of whack. Even with the extra day, we may be headed for problems down the line.

Our modern "Gregorian" calendar has been used by the Roman Catholic Church since 1582 and was adopted by England in 1752. But University of Maryland physicist David Book points out there are still a couple of problems with the system. In a recent letter to the Washington Post, he mentions one he calls the "Y5K problem."

Our modern calendar is designed with the seasons in mind. It is supposed to match up with what a farmer considers a year, or the time between two vernal equinoxes. (The vernal equinox, which marks the start of spring, occurs on the day in which the Sun rises over Earth's equator.) Using this definition, a year is 365.2422 days. By adding leap years at regular intervals, our modern calendar sets an average year at 365.2425 days -- very close to the length between vernal equinoxes but with a slight discrepancy of .0003 days.

The discrepancy may be small, but it adds up. Geoff Chester, with the US Naval Observatory (whose Time Service Department keeps the official time for the United States) points out that we are already "three hours ahead of what the seasons tell us." If we do nothing, our calendar will be a day ahead of schedule in 2915 years. Book calls this the "Y5K problem," because it would occur roughly around the year 5000.

Book also says that we need to think about fixing the problem now. "These errors accumulate. The longer we wait to make the correction, the more disruptive it will be." There are even suggestions floating around for how to make the change.

Chester says he's seen "one or two proposals to refine the Gregorian calendar by one leap day." In one such proposal, he explains that we would continue with the "normal" Gregorian rules with one exception--years divisible by 4000 (such as 4000 AD and 8000 AD), which are leap years under the present system, would become ordinary years. "Thus, you'd have 969 leap days every 4000 years," says Chester, "resulting in an average calendar year of 365.24225 days." With this method, Chester days "we won't get a full day out of kilter for some 15,000 years." Whether or not the Gregorian calendar will actually be changed, however, only time will tell.

###

Rory McGee
Inside Science News Service
(301) 209-3088
Rmcgee@aip.org

Ben Stein
Inside Science News Service
(301) 209-3091
Bstein@aip.org

EXPERTS:
David Book
Physicist
University of Maryland
(301) 405-7580
book@avl.umd.edu

Geoff Chester
US Naval Observatory
(202) 762-1438
grc@usno.navy.mil

Story Source:

The above story is based on materials provided by American Institute of Physics -- Inside Science News Service. Note: Materials may be edited for content and length.

American Institute of Physics -- Inside Science News Service. "The Y5K Bug? Hurdling The Leap Day Problem." ScienceDaily. ScienceDaily, 28 February 2000. <www.sciencedaily.com/releases/2000/02/000225115345.htm>.
American Institute of Physics -- Inside Science News Service. (2000, February 28). The Y5K Bug? Hurdling The Leap Day Problem. ScienceDaily. Retrieved August 29, 2014 from www.sciencedaily.com/releases/2000/02/000225115345.htm
American Institute of Physics -- Inside Science News Service. "The Y5K Bug? Hurdling The Leap Day Problem." ScienceDaily. www.sciencedaily.com/releases/2000/02/000225115345.htm (accessed August 29, 2014).

## More Space & Time News

Friday, August 29, 2014

### Featured Research

from universities, journals, and other organizations

### Featured Videos

from AP, Reuters, AFP, and other news services

Experiment Tests Whether Universe Is Actually A Hologram

### Experiment Tests Whether Universe Is Actually A Hologram

Newsy (Aug. 27, 2014) — Researchers at Fermilab are using a device called "The Holometer" to test whether our universe is actually a 2-D hologram that just seems 3-D. Video provided by Newsy
SpaceX’s Falcon 9 Rocket Explodes After Liftoff

### SpaceX’s Falcon 9 Rocket Explodes After Liftoff

Newsy (Aug. 23, 2014) — The private spaceflight company says it is preparing a thorough investigation into Friday's mishap. Video provided by Newsy
Did Russia Really Find Plankton On The ISS? NASA Not So Sure

### Did Russia Really Find Plankton On The ISS? NASA Not So Sure

Newsy (Aug. 21, 2014) — Russian cosmonauts say they've found evidence of sea plankton on the International Space Station's windows. NASA is a little more skeptical. Video provided by Newsy
Space to Ground: Hello Georges

### Space to Ground: Hello Georges

NASA (Aug. 18, 2014) — Europe's ATV-5 delivers new science and the crew tests smart SPHERES. Questions or comments? Use #spacetoground to talk to us. Video provided by NASA

## Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):

Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

## In Other News

... from NewsDaily.com

Save/Print:
Share:

## Free Subscriptions

Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

## Get Social & Mobile

Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

## Have Feedback?

Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web