2897: Light Leap Years

2024-02-21T18:40:46Z

Talosine: Keeping up the fight against the Papal Shadow Forces (Or in other words, I added a citation needed joke.)

{{comic
| number = 2897
| date = February 21, 2024
| title = Light Leap Years
| image = light_leap_years_2x.png
| imagesize = 288x389px
| noexpand = true
| titletext = When Pope Gregory XIII briefly shortened the light-year in 1582, it led to navigational chaos and the loss of several Papal starships.
}}

==Explanation==
{{incomplete|Created by a LIGHT LEAP SECOND - Please change this comment when editing this page. Do NOT delete this tag too soon.}}

A {{w|light year}} is a unit of distance, commonly used in astronomy, equal to the distance light travels in a vacuum in one year; the year used is the {{w|Julian year (astronomy)|Julian year}}, or 365.25 days. The joke of this strip is based on the fact that "one year" isn't a precise unit of measurement: there have been different definitions, evolving over time, of what what constitutes a year. The Gregorian calendar (the one most commonly used in modern times) includes a system of {{w|leap year|leap years}} in which an additional day is added every fourth year (with some exceptions) to make up for incompatibilities between day and year cycles. This temporarily changes the length of a year from 365 to 366 days, which could be taken to change the length of a light year. In this comic, [[Randall]] assumes that a light year is based on the length of the ''current'' year, which means that during leap years, it's based on 366 days, and during non-leap years, 365 days. That means that at the start and end of leap years, databases with astronomical distances have to be adjusted.

2024 is a leap year in the {{w|Gregorian calendar}} used in most parts of the world, and leap day (Feb. 29) was just over one week away when this comic was released. The comic portrays [[Cueball]] and [[Ponytail]] updating astronomical distances in some sort of database, noting how long and unpleasant the process is; the caption reveals that the reason is that leap years "make light-years 0.27% longer" (366/365 = 1.0027397...). This makes the distance to Alpha Centauri "0.27% shorter".

Standardized systems of measurement naturally don't change continually. As the comic points out, the difficulty in having to regularly update every reference to these units would be enormous and pointless. In real life, a light year is defined by the {{w|Julian year (astronomy)|Julian year}}, defined as 365.25 days, with each day being 86,400 SI seconds in length. This results in a light year which is standardized at 9,460,730,472,580.8 km, no matter how long the calendar year may be.

The title text jokes that {{w|Pope Gregory XIII}}, the originator of the Gregorian calendar, "briefly shortened the light-year in 1582." In reality he shortened the year, as he decided to advance the Julian calendar by 10 days to make up for excess past leap days, leading to "navigational chaos and the loss of several Papal starships". This is of course ludicrous, as there were no starships in the 16th century, there's never been a "Papal starship",{{Citation Needed}} and the light-year wasn't developed as a unit of measurement until 1838. The joke is that the evolving and somewhat loose and changing definitions of early calendars had significant impacts on the units of measurement we still use today. Such changes were of only minor significance at the time, but as technology has advanced and become increasingly reliant on precise and consistent measurements, such changes could be disastrous.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[Cueball is sitting at his laptop and leaning to the back of his office chair, while having his other hand on the laptop. He is looking at Ponytail standing behind him. The text from the laptop screen is shown above it, indicated with a zigzag line.]
:Cueball: It took until February, but I finally got all the distances updated!
:Ponytail: I really wish we didn't have to do this.
:[Laptop screen:]
:Proxima Centauri
:Distance: [in red, crossed out] <s>4.2493 ly</s>
:[in green] 4.2377 ly/
:[Caption below the panel:]
:Astronomers hate leap years because they make light-years 0.27% longer.

{{comic discussion}}

[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics with color]]
[[Category:Astronomy]]
[[Category:Time]]
[[Category:Calendar]]
[[Category:Comics featuring real people]]

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2897: Light Leap Years