Topic: Time (Page 3)
You are looking at all articles with the topic "Time". We found 32 matches.
Hint:
To view all topics, click here. Too see the most popular topics, click here instead.
🔗 Pax Calendar
The Pax calendar was invented by James A. Colligan, SJ in 1930 as a perennializing reform of the annualized Gregorian calendar.
Discussed on
- "Pax Calendar" | 2023-05-12 | 48 Upvotes 24 Comments
🔗 Tell HN: Happy Solstice
The winter solstice, hiemal solstice or hibernal solstice, also known as midwinter, occurs when one of the Earth's poles has its maximum tilt away from the Sun. It happens twice yearly, once in each hemisphere (Northern and Southern). For that hemisphere, the winter solstice is the day with the shortest period of daylight and longest night of the year, when the Sun is at its lowest daily maximum elevation in the sky. At the pole, there is continuous darkness or twilight around the winter solstice. Its opposite is the summer solstice.
The winter solstice occurs during the hemisphere's winter. In the Northern Hemisphere, this is the December solstice (usually 21 or 22 December) and in the Southern Hemisphere, this is the June solstice (usually 20 or 21 June). Although the winter solstice itself lasts only a moment, the term sometimes refers to the day on which it occurs. Other names are "midwinter", the "extreme of winter" (Dongzhi), or the "shortest day". Traditionally, in many temperate regions, the winter solstice is seen as the middle of winter, but today in some countries and calendars, it is seen as the beginning of winter. In meteorology, winter is reckoned as beginning about three weeks before the winter solstice.
Since prehistory, the winter solstice has been seen as a significant time of year in many cultures, and has been marked by festivals and rituals. It marked the symbolic death and rebirth of the Sun. The seasonal significance of the winter solstice is in the reversal of the gradual lengthening of nights and shortening of days.
Discussed on
- "Tell HN: Happy Solstice" | 2009-12-21 | 37 Upvotes 19 Comments
🔗 Time formatting and storage bugs
In computer science, time formatting and storage bugs are a class of software bugs which may cause time and date calculation or display to be improperly handled. These are most commonly manifestations of arithmetic overflow, but can also be the result of other issues. The most well-known consequence of bugs of this type is the Y2K problem, but many other milestone dates or times exist that have caused or will cause problems depending on various programming deficiencies.
Discussed on
- "Time formatting and storage bugs" | 2021-12-26 | 47 Upvotes 2 Comments
🔗 Atmos Clock
Atmos is the brand name of a mechanical torsion pendulum clock manufactured by Jaeger-LeCoultre in Switzerland which does not need to be wound manually. It gets the energy it needs to run from temperature and atmospheric pressure changes in the environment, and can run for years without human intervention.
The clock is driven by a mainspring, which is wound by the expansion and contraction of liquid and gaseous ethyl chloride in an internal hermetically sealed bellows. The ethyl chloride vaporises into an expansion chamber as the temperature rises, compressing a spiral spring; with a fall in temperature the gas condenses and the spring slackens. This motion constantly winds the mainspring. A temperature variation of only one degree in the range between 15 °C (59 °F) and 30 °C (86 °F), or a pressure variation of 3 mmHg, is sufficient for two days' operation.
In order to run the clock on this small amount of energy, everything inside the Atmos has to work in as friction-free a manner as possible. For timekeeping it uses a torsion pendulum, which consumes less energy than an ordinary pendulum. The torsion pendulum has a period of precisely one minute; thirty seconds to rotate in one direction and thirty seconds to return to the starting position. This is thirty times slower than the 0.994 m (39.1 in) seconds pendulum typically found in a longcase clock, where each swing (or half-period) takes one second.
Discussed on
- "Atmos Clock" | 2015-06-14 | 37 Upvotes 6 Comments
🔗 Tell HN: There will be a Blue moon in December
A blue moon is an additional full moon that appears in a subdivision of a year: either the third of four full moons in a season, or a second full moon in a month of the common calendar.
The phrase in modern usage has nothing to do with the actual color of the Moon, although a visually blue Moon (the Moon appearing with a bluish tinge) may occur under certain atmospheric conditions – for instance, if volcanic eruptions or fires release particles in the atmosphere of just the right size to preferentially scatter red light.
Discussed on
- "Tell HN: There will be a Blue moon in December" | 2009-12-07 | 29 Upvotes 8 Comments
🔗 Multiple Time Dimensions
The possibility that there might be more than one dimension of time has occasionally been discussed in physics and philosophy. Similar ideas appear in folklore and fantasy literature.
Discussed on
- "Multiple Time Dimensions" | 2024-02-20 | 29 Upvotes 5 Comments
🔗 Hindu units of time
Hindu texts describe units of Kala measurements, from microseconds to Trillions of years. According to these texts, time is cyclic, which repeats itself forever.
Discussed on
- "Hindu units of time" | 2015-03-23 | 19 Upvotes 7 Comments
🔗 Unix time - 15:30:08 UTC on Sun, 4 December 292,277,026,596
Unix time (also known as Epoch time, POSIX time, seconds since the Epoch, or UNIX Epoch time) is a system for describing a point in time. It is the number of seconds that have elapsed since the Unix epoch, that is the time 00:00:00 UTC on 1 January 1970, minus leap seconds. Leap seconds are ignored, with a leap second having the same Unix time as the second before it, and every day is treated as if it contains exactly 86400 seconds. Due to this treatment, Unix time is not a true representation of UTC.
Unix time is widely used in operating systems and file formats. In Unix-like operating systems, date
is a command which will print or set the current time; by default, it prints or sets the time in the system time zone, but with the -u
flag, it prints or sets the time in UTC and, with the TZ
environment variable set to refer to a particular time zone, prints or sets the time in that time zone.
Discussed on
- "Unix time - 15:30:08 UTC on Sun, 4 December 292,277,026,596" | 2014-06-03 | 11 Upvotes 10 Comments
🔗 Happy (Summer|Winter) Solstice - 11:28 Zulu time.
A solstice is an event occurring when the Sun appears to reach its most northerly or southerly excursion relative to the celestial equator on the celestial sphere. Two solstices occur annually, around June 21 and December 21. In many countries, the seasons of the year are determined by reference to the solstices and the equinoxes.
The term solstice can also be used in a broader sense, as the day when this occurs. The day of a solstice in either hemisphere has either the most sunlight of the year (summer solstice) or the least sunlight of the year (winter solstice) for any place other than the Equator. Alternative terms, with no ambiguity as to which hemisphere is the context, are "June solstice" and "December solstice", referring to the months in which they take place every year.
The word solstice is derived from the Latin sol ("sun") and sistere ("to stand still"), because at the solstices, the Sun's declination appears to "stand still"; that is, the seasonal movement of the Sun's daily path (as seen from Earth) pauses at a northern or southern limit before reversing direction.
Discussed on
- "Happy (Summer|Winter) Solstice - 11:28 Zulu time." | 2010-06-21 | 16 Upvotes 4 Comments
🔗 Swiss Railway Clock
The Swiss railway clock was designed in 1944 by Hans Hilfiker, a Swiss engineer and Swiss Federal Railways (SBB) employee, together with Moser-Baer, a Swiss clock manufacturer, for use by the SBB as a station clock. In 1953, Hilfiker added a red second hand in the shape of the baton used by train dispatch staff., giving the clock its current appearance.
Discussed on
- "Swiss Railway Clock" | 2023-01-16 | 10 Upvotes 4 Comments