In the northern hemisphere, the sun travels to the right as it rises, and travels to the right as it sets. Never to the left, and never straight up and down.
Here are four questions that I hope you will answer for me: 1. Does the sun rise or set straight up and down at the equator, if even for one or two days a year? 2. Does a city on the equator enjoy two summers per year, along with a spring and a fall? 3. Does a city on the equator witness a travel-to-the-left sunrise and sunset during our summer, and a travel-to-the-right sunrise and sunset during our winter? 4. Does a city in the southern hemisphere witness a travel-to-the-left sunrise and sunset all year long (if at all)?
Yes, you’ve pretty much got it, except that for number 2, there are two springs and falls along with two summers. Of course the climatic effects are rather more complicated and dependent on the geography, but I don’t think that’s what you’re asking.
A city on the equator will always see the Sun moving straight up at rising, and straight down at setting. Right at the equator, the days are always the same length (well, to within a few seconds), and tropical areas are generally warm year-round, so one doesn’t usually speak of summer and winter near the equator. To the extent that equatorial folks care about seasons, it’s usually rainy season and dry season, but when exactly those fall depends on all sorts of complicated features of geography, and there might be one or two of each each year. And a city in the southern hemisphere will, as you surmise, see the sun moving in a generally leftwards direction, both at rising and setting (and in between).
Yes. Right on the equator, the Sun will pass directly overhead on the equinoces, be north of directly overhead from March to September, and be south of directly overhead from September to March.
Chronos, I trust your science answers a lot usually, but are you right about this? I’d think during the Northern Hemisphere’s summer, the sun will not be rising straight up but at an angle towards the north (left). It’s not going to be directly overhead at noon so it’s got to go northward at some point, and I’d think it would always be tracing over a great circle route
Something else I noticed in my one trip to the Southern Hemisphere (Peru): the moon phases are the mirror image of what they are here. Here, when the moon is in first quarter, only the right half is visible, and only the left half is visible during the last quarter. The situation is opposite south of the equator.
I’m not sure about this. On the equator, on the June solstice, it seems that the sun would rise to the left, be at some point north at noon, and then set in the west to the right. On the December solstice, it seems the opposite. Sun rises (still in the east) heading south (to the right), to be due south at noon, and then to set sliding to the left. I think, but am not sure, that the sun always rises and sets at (at least very close to) exactly due east or west, but I think there’s still some horizontal motion going on.
I’m also pretty sure, to answer the OP, that it’s not a northern/southern hemisphere thing, but an “Are you between the tropics of Cancer and Capricorn?” thing. If yes, then I think the sunrise and sunset directions will change over the year depending on whether the sun is north or south of you (that is, if the latitude of the point of the earth that is closest to the sun is north or south of your latitude.
Similarly, all bets are off in the Arctic and Antarctic circles, where, for at least part of the year, the sun doesn’t set at all. It just goes in circles. Also, east and west tend to make little sense there.
The Sun doesn’t trace a great circle route across the sky; rather, it traces a “line-of-latitude” path across the celestial sphere (technically, a line of constant declination.) These lines are straight up (or down) where they intersect the Equator horizon, but they “curve away” from great circles as they ascend. However, the point of sunrise/sunset is not due east or due west, except on the equinoxes.
No matter where you are on the Earth, the Sun always rises north of east (and sets north of west) from March to September, and rises south of east (and sets south of west) from September to March. On the equinoxes, it rises & sets due east & west no matter where you are on the Earth. (This does ignore the small changes in he Sun’s position on the celestial sphere over the course of the day, though.)
Holy Cow! I sure came to the right place to ask this question. I’ve been wondering about this for years.
Since there are so many (different) answers, I’m gonna have to pour over the responses and put them all together. Next, I’m going to shine a spotlight onto a globe and see what happens when I tilt it North and South.
The TV show “SouthPark” aired an episode where the kids were in Costa Rica, and they showed the sun rising from right to left. Since I was already fascinated with the subject, I had to wonder if the SP creators goofed up, or if they knew what they were doing.
Thanks everyone.
Your whole thinking about “right” & “left” is a barrier to understanding.
When you’re well north in the northern hemisphere (like anyplace in the US) and want to look towards the Sun, you face south. The Sun *always *moves from east to west and when you face south, east is to your left & west to your right. So the sun seems to move left-to-right for somebody facing south.
But if you turn around and face north & look over your shoulder towards the sun, yuo’ll see it moving from your right to your left. It didn’t change; you did. It’s still going from east to west.
Now for somebody well south in the southern hemisphere (say Australia), they face *north *to look towards the sun. The sun still moves east to west. But for somebody facing north east is to their right & west is to their left. So the Sun moves from the viewer’s right to left.
Taking both those together we see that facing north the Sun always moves right-to-left & facing south the Sun always moves left-to-right. It doesn’t matter at all where on the Earth your’re standing: north, south, equator, or pole. The sun’s motion is the same direction everywhere. All that matters is which way you’re facing.
Because the Earth’s rotational axis is tilted 23-ish degrees versus the orbital plane, the Sun’s path through the sky isn’t constant year round, not even on the Equator. And except on the equinoxes the Sun does not rise or set vertically for an observer on the Equator.
Seasons are more about the weather than they are about the astronomy. And as noted by others above, tropical areas don’t really have the 4 seasons we see in the so-called temparate zone where much of the US & Europe is located.
It’s possible that it’s a deliberate spoof of live-action movies that show right-to-left sunrises. Film crews don’t like getting up before dawn any more than anyone else, so most sunrises in films are actually reversed sunsets. You can, of course, flip the film left-right when you do this, to compensate, but they often don’t bother.
I thought this when I first read the OP as well, before I figured out what he was asking. (Which I admit wasn’t phrased very well.) He was talking about the movement of the sun when the observer is facing the direction of the sunrise or sunset. In the northern hemisphere (north of the Tropic of Cancer), as the sun rises in the east, it moves up and towards the south, which is to your right as you face east. And as it sets in the west, it moves down and towards the north, which is to your right as you face west. In the southern hemisphere (again, south of the Tropic of Capricorn), the sun will move up and north as it rises, and down and south when it is setting, in both cases to the left from the POV of an observer facing the sun.
Put another way: if you face the sun at sunrise, and attempt to continue facing the sun all day, you will be slowly turning your body to the right all day if you are in the north, and slowly turning your body to the left all day if you are in the south (while also craning your neck to face upwards to some degree as noon goes by).
Hi Chronos, thanks for your replies. To side-step the original subject slightly: Being a photographer myself, I believe the film crews use a reverse sunset to represent a sunrise because it’s hard to pinpoint the exact spot where the sun will break the horizon during sunrise.
Hm, that hadn’t occurred to me, and is another good reason to do it that way. It’s not all that hard to calculate, given the latitude and time of year, but I imagine that’s not the sort of thing they teach in film school.