In Longitudes, what is the different between East and West?

wherearewe45 · 22-01-2021 08:09PM #1

Here in Ireland, when mapping in degrees, minutes and seconds we are roughly 53o43'56 N and -9o43'56 X. Where I have the X, should this be W or E. E seems far more common and does kinda make sense in that because we are West we are "minus E" but we are actually West, so should it be "W" without the minus?

Fann Linn · 22-01-2021 08:15PM

wherearewe45 wrote: »

Here in Ireland, when mapping in degrees, minutes and seconds we are roughly 53o43'56 N and -9o43'56 X. Where I have the X, should this be W or E. E seems far more common and does kinda make sense in that because we are West we are "minus E" but we are actually West, so should it be "W" without the minus?

West without the minus would be my reckoning.

Fann Linn · 22-01-2021 08:20PM

Found this by googling 'country coordinates',

Ireland 53 00 N, 8 00 W

HeidiHeidi · 22-01-2021 08:23PM

I have never seen a minus used in all my years of navigating.

You're either east or west of the prime meridian.

oriel36 · 24-01-2021 01:51PM

Longitude is a system based on the rotation of the Earth using noon and the fixed/central/stationary Sun as a reference once every 24 hours or 4 minutes of rotation for each degree of geography/geometry. Dublin (Dunsink Observatory) is 25m 21 seconds or 6. 33 degrees West of the Greenwich meridian based on this inviolate fact.

It is disputed by the astrophysics community who attempt to impose an alternative system (RA/Dec) based on tethering the Earth's rotation directly to the daily change in position of stars in a circumpolar format -

https://www.youtube.com/watch?v=BYy0EQBnqHI

Sadly, for the geographical community, this represents a loss of the planet's geometry and geography for the late 17th-century conclusion assigns a 360 degree rotation in 23 hours 56 minutes 04 seconds. This includes the loss of the information contained in the Lat/Long system as it assigns a wrong rotational velocity for the Earth's equator -

Rotation period - 23h 56m 4s
Equatorial rotation velocity - 1674.4 km/h; 1040.4 mph

https://en.wikipedia.org/wiki/Earth

Once people get over their initial dismay, they are obligated to restore some sanity to the geography of the Earth rather than going on a 250+ year misadventure with timekeeping. People can do better.

Popoutman · 28-03-2021 06:30PM

Convention has it that east is positive from the Prime Meridian, and that going west is negative. Most likely because the timezones work the same way, hours add going east and subtract going west.

In situations where it's not possible to enter the letters W or E (some websites will only allow numerical type entry for lat/lon), the negative sign for West should be understood correctly by the system in use.

Putting both the letter W and the minus modifier should not both be present, as they should be mutually exclusive. Either the letter signifies the side of meridian, *or* the minus or lack thereof determines the same. Although, it is relatively trivial to code for this. If letter, ignore minus; if no letter, check for minus. Its that it's confusing to most human readers unfamiliar with the conventions that it presents a little problem.

(Please ignore the previous poster's proof of an unfortunate inability to understand that the earth does ~366 rotations a year relative to the stars and one rotation around the sun in the same time, it's been a consistent blind spot of that poster over the years, it's been done to death and caused a banning from the weather and astronomy board due to their antics and consistent drivel on the subject.)

oriel36 · 28-03-2021 10:27PM

Here is a gift for those who appreciate geography, timekeeping and longitude.

DST has never been put in context before and it can be slightly intricate at first. Although the hour hand of the clock moves forward presently within the 24 hour cycle, the effect is that clock noon within the 24 hour cycle and natural noon within the day/night diverges backwards by one hour.

The Earth rotates at a rate of 1 degree for every 4 minutes or 15 degrees per hour, which, in turn, represents a time zone. Galway is roughly 9 degrees West of London a slightly higher towards the North Pole so its sunrise time is about 1/2 an hour later even though within the same time zone.

https://www.timeanddate.com/sun/uk/london

If the reader goes to the sunrise/noon/sunset reading for Saturday (27th), natural noon and clock noon are anchored to each other, but when DST is applied today (28th), clock noon and natural noon diverge backwards by one hour. Go to the graphic and pick up the Sun and move it backwards by 1 hour representing clock noon. The asymmetry created is that the length of time from natural sunrise to clock noon is shortened by an hour while the length of time from clock noon to sunset is lengthened by an hour. This is why people experience longer daylight coincident with what is clock is telling them.

It is exquisite, but such is the flexibility of time zones linked to the planet's geography and the 24 hour and Lat/Long systems for those capable of admiring part of the framework.

Once again, the clocks go backwards or diverge from the natural sunrise/noon/sunset cycle by one hour as DST, so those who describe clocks going forward are in error.

In Longitudes, what is the different between East and West?

Comments