Thank you for submitting a question.
This is mostly a matter of science, rather than ethics. I am not a scientist, but here goes. :-)
You are aware that time zones vary as one moves around the globe from east to west. In the U.S., that is what explains the Eastern, Mountain, Central, and Pacific time zones. We complicate that in most places by also doing an adjustment for Daylight Savings Time; this is to ‘conserve’ daylight, a concern during the shortest days of the year. None of that, however answers your question. Instead, we have to think about the geography and topography of the location where the candles are to be lit.
Let’s take the situation in my immediate area. I live in Virginia, in the Central Shenandoah Valley region. This is in the same Eastern time zone as New York City, Atlanta, Baltimore, Philadelphia, and so on. Candle lighting times, however, vary in my region from all of those locations, and from place to place locally! Let’s look at why.
Our illustrative example is of someone living in a Valley, the low land between two sets of mountains, as opposed to someone else living to the east or west of both mountains, or on top of one of the mountains. For this mental picture, think of the sun’s rays coming from the west (in the afternoon), and moving from left to right, at some angle. The topmost parts of the lines forming the ‘V’ would actually be the peaks of the mountains, and the valley would be the area at the bottom inside the letter ‘V’. (You can actually draw this on paper as a simple diagram, if that helps.)
First, the rays of the sun travel in straight lines (for our purposes – we are not going to try to work with the theory of relativity and the bending of light and space!) At noon, the sun would be directly overhead, and the sun’s rays would be falling at close to a 90 degree angle, straight ‘down’. The rays would hit the peaks and the valley at virtually the same time (we are not going to worry about any differences in speed of particles of light travelling at the speed of light – that is too fast to concern us for our purposes).
As the afternoon wore on, however, the sun would ‘move’ with the rotation of the earth westward in the sky, so to the left and ‘lower’ in our mental picture, and the angle at which the rays of light would be striking the earth would increase gradually from 90 degrees to 180 degrees as the sun ‘moved’ towards the west and sank towards the horizon.
Thinking about close to sundown, the sun is far to the west and relatively close to the horizon. At some point, when the rays of the sun are at something greater than a 90 degree angle, the mountain on the left will begin to cast a shadow into the valley. At a given moment, no rays of the sun will strike the ground or be visible at the eastern foot of the mountain. As the sun moves farther along towards the west, and ‘down’ towards the horizon, the shadow will lengthen and the sun will be blocked on the inner (left or valley) side of the right hand mountain. Still later, the left hand mountain’s shadow will cover the peak of the right hand mountain. And later still, the sun will drop below the horizon, and there will be a shadow formed by the earth itself, and there will be no sun’s rays that strike the peak of the left hand mountain. Once (all of) the sun passes the horizon, we have reached sundown, and no rays of light hit the area in question directly (it is night). All of this occurs at a specific pace, and the process spans a period of elapsed time. This difference in the perceived instant of ‘sundown’ is why sundown times vary.
Using a slightly different example: if the earth were perfectly smooth, like a ball, there would be only one time for sundown throughout a time zone, but because the earth has valleys and mountains, and buttes and fjiords and dales and hollows and glens, and many other topographical features that change ‘height’, and many of which cast shadows or are thrown into shadow, there are a variety of different ‘sundown’ times depending on where you are in relation to the various topographical features! Again, using a ball as an example, if you stuck a triangular block on that ball with the peak pointing directly to the right, and held a light steadily out to the left, shining directly at the ball, the light would strike half that ball, more or less all at once. If you turn the ball so the peak of the triangle moved from that zero degree point, towards and beyond the 90 degree point (the peak pointing straight up), you would observe that the shadow of that triangle would cause the light to be blocked to the right of the triangle much sooner in that rotation than on the rest of the surface of the ball. For those we imagine to be living on the surface of the ball just to the left of the triangle, sundown would occur later than it would for those living on the surface of the ball just to the right of that triangle.
Candle lighting time is related to sundown; if sundown time varies, so does candle lighting time.
I hope this helps explain what is happening.
Rabbi Joe Blair
Administrators Note: Because this is not an ethical question, nor does it involve Jewish Values, this is the only answer that will be provided.
Answered by: Rabbi Joseph Blair