Stupid question time. I’m in the northern hemisphere, well north of the Tropic of Cancer. Why does the sun rise in the northeast? I drive an east/west road to work everyday and the sunrise appears to be at least 20 degrees north of the road. At noon, the sun appears to be exactly where it should be.
I’m having a hard time wrapping my head around this. I’m sure that it has something to do with the Earth being a sphere but that’s not helping. I’m not sure what to google either. The wiki on sunrise wasn’t much help.
It is due to the tilt of the earth. Sunrise is north of east in summer, and south of east in winter, in North America. Experiment with different dates on this site.
As Crotalus notes, it’s because of the tilt of the Earth, which causes the declination of the Sun to vary over the course of the year. The Wikipedia article provides an instructive example: suppose the Earth’s axis was tilted over at 90°, so that on the summer solstice the axis of rotation of the Earth pointed directed at the sun. (In other words, the Sun was directly over the North Pole.) Suppose, for the sake of argument, that you were on the Equator. On the summer solstice, you would see the Sun towards the North, directly lined up with the Horizon.
Now wait for three months, until the fall equinox. The Earth has now gone a quarter of the way around its orbit; but, importantly, the axis of rotation still points the same direction. This means that the Sun is now directly above the Earth’s Equator, which means that it will rise and set due east and west, respectively. In the intervening three months, the point of sunrise will have shifted smoothly from due north to due east. As time passes from fall into winter, the sunrise will continue to move south; when it gets to be the winter solstice, the sun is now directly over the South Pole, and so you (on the equator) would see the Sun at due south. Finally, as the Earth goes the rest of the way around its orbit, the sunrise would reverse its path — proceeding from south, back to due east (on the spring equinox, when the Sun is over the equator again), and finally back to due north after a full year has passed.
This is what would happen in the extreme case of an axial tilt of 90°. The earth’s axis isn’t nearly as tilted over as that (and good thing, too, for the existence of life on Earth), which means that the Sun is never directly over the North Pole or South Pole. However, it does get closer to being directly over the North Pole at the summer solstice, and closer to being over the South Pole at the winter solstice. So the Sun rises somewhere in the northeast during the summer, and in the southeast in the winter.
If you replace “in summer” with “March through September” and “in winter” with “September through March”, then this is true everywhere on Earth.
For a different take on it, it might help to describe this in perceptual terms: We in the Northern Hemisphere, north of the Tropic of Cancer, are accustomed to thinking of seeing the sun always south of us. But it isn’t really. In the summer, think of the sun as following a great arc from sunrise somewhere in the northeast, across the sky toward the south, then seeming to head back northward to set in the northwest. In the summer, centering around the summer solstice, the farther north you are the greater this northward shift and the larger this arc and the longer the day, until you get north of the Arctic Circle where the arc is so huge that it’s a complete circle around the entire sky. There, the land of the midnight sun, the sun never sets at all – it does a complete circle of the sky and covers all points of the compass.
Well, maybe I’ve been misunderstanding all these years. My understanding is that an observer standing north of the Tropic of Cancer would never seen the sun rise directly in the east nor set directly to the west.
What he said. I think I’m beginning to picture it, but I have a follow-up question. Above what latitude will one never see the sun rising north of east? 45N or so?
It’s actually more pronounced the farther north you go. At the arctic circle, the sun sets (and then immediately rises) due north on the summer solstice.
Here in London (approximately 51ºN) the sun rose at an azimuth of 54 degrees this morning, or 36 degrees north of east, according to this handy calculator.
At its furthest north, in midsummer, the azimuth is 49 degrees, or 41 degrees north of east.
In the far north of the UK, in Shetland, which is above 60ºN, the midsummer sun rises at 34 degrees, circles the sky for almost 19 hours, and then sets at 326 degrees.
On the equinoxes (March 21 & September 21, give or take), the Sun rises due east and sets due west for everyone on Earth. You may be thinking of the fact that the Sun will never be directly overhead for anyone north of the Tropic of Cancer (or south of the Tropic of Capricorn).
Imagine that you are at the North Pole. The summer sun never sets at all. It just circles around you, close to the horizon. Now start walking south (really fast). The further south you go, the closer the sun dips toward the north horizon. When you reach the Arctic Circle, the midnight dip of the sun will touch the horizon, due north of where you are. Keep going south, and the sun will dip lower and lower below the horizon, still always to the north. As long as the number of hours of daylight are longer than the number of hours of darkness, those sunrises and sunsets will remain to the north of your east-west line, because the sun is still just circling around you, like it did at the North Pole, but you have sunsets and sunrises because it dips down below the North Pole.
A sun path diagram will show where on the horizon the sun will set/rise at different times of the year. Diagrams vary depending on your latitude. Here’s one for Chicago. Here’s a site then even shows a sun path diagram projected in 3D.