If you open up your Farmers’ Almanac (you do have a copy, right?) to the calendar section that contains many pages of astronomical data, you’ll see entries listing the sunrise and sunset times for each day of the year. The only problem is, depending on where you live, those time may not be accurate for your area. What gives?
The sunrise and sunset times listed in the Farmers’ Almanac are for a specific geographic location — 40° N Latitude and 75° W Longitude for northern U.S. states, and 35° N Latitude and 90° W Longitude for southern states — chosen because data suggests that the population is densest near those areas. The further you live from those exact coordinates, though, the more drastically your local sunrise and sunset times might differ from the published times.
That’s because sunrise and sunset times depend on a number of variables, including longitude, latitude, altitude, and location in relationship to your specific Time Zone. Here’s a look at how a each of these factors affects your area’s sunrise and sunset times.
Longitude: Longitude lines are the imaginary lines that run vertically around the globe, intersecting at the North and South Poles. Longitude is a way of talking about how far east or west a location is in relationship to one specific imaginary line, called the Prime Meridian, that runs through the town of Greenwich, England. Because the Earth spins clockwise, the Sun appears to the east of any given location each day. It takes about one hour for the Sun’s light to move 15° longitude. This is why the Sun’s rays reach the East Coast each day before the West Coast.
Time Zone: Time zones were created to acknowledge the fact that the Sun is not “up” at the same time everywhere around the globe. Because the Sun’s light moves across the Earth at a rate of 15° longitude per hour, people divided the Earth into 24 roughly equal sections of about 15° each, and assigned a one-hour time difference to each successive zone. This means that, all other things being equal, the Sun rises at roughly the same time no matter which time zone you’re in. Unfortunately, it’s not quite that simple. First of all, the many time zones don’t line up perfectly with the longitude lines, due to political and other complications. In addition, not all of us live right at the easternmost edge of our respective time zones. The further west you live within your time zone, the later your sunrise will be. There is a simple, but somewhat inexact, way to figure this out. For every 70 miles you travel west within your time zone, sunrise will be about four minutes later. This time decreases somewhat the further you move from the Equator, though. That’s because of latitude …
Latitude: Latitude lines are imaginary lines that encircle the globe horizontally. Latitude is a way of talking about how far north or south a location is in relationship to the Equator, the imaginary line that runs around the center of the globe. Unlike longitude lines, latitude lines never intersect. Because the Earth’s circumference is smaller near its poles than it is around its center, extreme northern or southern locations experience greater variations in the length of their days than locations closer to the Equator. While equatorial locations get approximately 12 hours of daylight and darkness each day, year-round, areas closer to the North and South Poles can experience several months of constant sunlight or darkness at a stretch. Most North Americans live somewhere between these two regions.
Altitude: As if all of these factors weren’t enough, altitude also plays a role. Generally speaking, the higher your location is, the earlier the Sun will rise, and the later it will set, compared to when it would for the same location if it were at sea level. An easy way to determine what effect altitude has is to remember than sunrise will be one minute earlier for every mile of altitude, and that sunset will be later by the same amount.
With all of these factors in play, which areas in the U.S. experience the earliest and latest sunsets of the year. Here’s a look:
Mars Hill, Maine, experiences the earliest sunrise in the contiguous United States, with the Sun coming up at 4:38 a.m. during mid-June each year. Mars Hill is not always the first place to see the Sun year-round, though. During the winter months, Cadillac Mountain, near Bar Harbor, Maine, sees the Sun first, while that honor goes to Quoddy Head in Lubec, Maine, as the equinoxes approach.
The earliest sunset of the year happens in Bar Harbor, Maine, where the Sun goes down at 3:44 p.m. during early December.
Fortuna, North Dakota, which sits far to the west of much of the rest of the Central Time Zone, bears the distinction having of both the latest sunrise and sunset of the year in the contiguous U.S. There, the sun rises at 8:48 a.m. in late December. In mid-June, the sun doesn’t set until 10:03 p.m.
Of course, Fotuna is not the last place in the U.S. to see the Sun go down. That happens in Cape Flattery, Washington, the northwesternmost point in the contiguous U.S. Because Cape Flattery isn’t as far from the eastern edge of the Pacific Time Zone as Fortuna is from the eastern edge of its time zone, sunrise and sunset times come a little earlier there. Its latest sunrise occurs at 8:09 a.m. late December, and the latest sunset happens at 9:23 p.m. late June.
Two other U.S. areas fall at the extreme western edges of their respective time zones. Ontario, Oregon, in the Mountain Time Zone, sees its latest sunrise at 8:22 a.m. in late December and its latest sunset at 9:34 p.m. in mid-June. Ontonagon, Michigan, in the Eastern Time Zone, has its latest sunrise at 8:42 a.m. in late December and its latest sunset at 9:55 p.m. in late June.
Of course, all of this pales in comparison to Barrow, Alaska, where the Sun stays down from November 20 until January 22, and stays up from May 12 until August 1 each year! A bit further south in Anchorage, mid-winter days are only five and a half hours long. The Sun comes up at 10:15 a.m. and goes down at 3:42 p.m. there.