Earth and Sun(ciechanow.ski)
ciechanow.ski
Earth and Sun
https://ciechanow.ski/earth-and-sun/
64 comments
What a beautiful, well designed and informative explanation of the complex earth / sun relationship. Well done!
One thing I would love to see is the path of the sun across the sky for different times of year, and different locations on earth.
Here in Seattle, the difference is fairly dramatic between winter and summer, and I've come to realize that the sun is never directly overhead, not even in summer. It would be interesting to see the difference between polar regions vs in the tropics also.
One thing I would love to see is the path of the sun across the sky for different times of year, and different locations on earth.
Here in Seattle, the difference is fairly dramatic between winter and summer, and I've come to realize that the sun is never directly overhead, not even in summer. It would be interesting to see the difference between polar regions vs in the tropics also.
Perhaps you are aware, but it is very simple to calculate.
(90-your latitude) + tilt of the earth (23.5 degrees) = maximum height of the sun during the year
(90-your latitude) - tilt of the earth (23.5 degrees) = minimum height of the sun during the year.
Effectively this means if your latitude is 23.5 or less, you get the sun directly overhead at some time during the year. If your latitude is above 67.5, you get polar night as the sun doesn't rise above the horizon (short one at 67.5, but as you go further toward the pole ever longer)
For Seattle, (90-47)+23.5=66.5 maximum. (90-47)-23.5=19.5 minimum.
(90-your latitude) + tilt of the earth (23.5 degrees) = maximum height of the sun during the year
(90-your latitude) - tilt of the earth (23.5 degrees) = minimum height of the sun during the year.
Effectively this means if your latitude is 23.5 or less, you get the sun directly overhead at some time during the year. If your latitude is above 67.5, you get polar night as the sun doesn't rise above the horizon (short one at 67.5, but as you go further toward the pole ever longer)
For Seattle, (90-47)+23.5=66.5 maximum. (90-47)-23.5=19.5 minimum.
Calling these the "maximum height" and the "minimum height" of the sun during the year makes it sound like the height of the sun will always lie between those two figures. That can't be the case -- they have night in the tropics too. Are these what I might call the "high maximum height", the yearly maximum of the maximum height of the sun on any given day, and the "low maximum height", the yearly minimum of the daily maximum height of the sun?
It’s the minimum and maximum angle between sun and horizon at midday on the solstices.
Yes, you are correct. My phrasing was unclear, especially in terms of "minimum".
The numbers are for the highest angle of Sun toward the horizon in a single day. This happens at solar noon (solar noon is the moment that Sun passes your local meridian/north south line).
The numbers are for the highest angle of Sun toward the horizon in a single day. This happens at solar noon (solar noon is the moment that Sun passes your local meridian/north south line).
Maybe minimum and maximum daily peak?
At my school we had this weird climbing frame called the "Pipehenge". I climbed on it for years before we eventually did a class on it and learned that it was an astronomic map: https://www.youtube.com/watch?v=BM4d02tjTqk
Looks they are no longer made, or are they?
I’d love to make one of those
Very much agreed. Things get weirder and weirder as you get towards the poles. At the poles themselves the sun spends half the year hidden, and the other half spiraling up and then down! But never gets very high above the horizon.
I've been thinking a lot about this lately and was thinking of making some educational YouTube videos about it!
I've been thinking a lot about this lately and was thinking of making some educational YouTube videos about it!
If you haven’t looked at that sort of thing on YouTube, don’t. Make your own videos first.
SunCalc (http://suncalc.net) has a visualization for sun position throughout the year and time of day. Another great app is Sun Surveyor for Android, which gives an augmented reality view of the sun's position and trajectory.
The free, cross-platform program Stellarium [0] will show that (among other things).
[0] http://stellarium.org/
[0] http://stellarium.org/
> I've come to realize that the sun is never directly overhead, not even in summer
It's only ever directly overhead in the tropics.
It's only ever directly overhead in the tropics.
.. which is defined to be between the tropic of cancer and tropic of capricorn; 23°26′12.2″ north and south of the equator respectively.
Which is because the earths axial tilt is that angle:
Earth's mean obliquity is currently 23°26′12.2″ (or 23.43672°) and decreasing.
https://en.wikipedia.org/wiki/Axial_tilt
Earth's mean obliquity is currently 23°26′12.2″ (or 23.43672°) and decreasing.
https://en.wikipedia.org/wiki/Axial_tilt
It's like I just read an epic story, still under impression ...
Quote: One day we’ll colonize other planets, those planets will have different suns, orbits, and rotations periods, yet a simple second will forever be tied to Earth and Sun.
I would definitely give my 'best web page 2019' to it. Bravo!
Quote: One day we’ll colonize other planets, those planets will have different suns, orbits, and rotations periods, yet a simple second will forever be tied to Earth and Sun.
I would definitely give my 'best web page 2019' to it. Bravo!
I’d like to know what tools were used to make these. Works great on mobile, usually these things break pretty badly, I didn’t see any bugs
Looks like it's just hand written javascript and webgl https://ciechanow.ski/js/earth_sun.js
One of the many ways you can tell how much passion went into this beautiful piece
Works excellent in Firefox
I remember spending a lot of time playing with a planets-and-gravity simulator on the Mac when i was a kid. I wrote a crappy clone of it as an applet for one of my first jobs!
This is the best web-based equivalent i found with a quick search:
https://hermann.is/gravity/
And this is a rather fine tutorial on writing your own:
https://css-tricks.com/creating-your-own-gravity-and-space-s...
This is the best web-based equivalent i found with a quick search:
https://hermann.is/gravity/
And this is a rather fine tutorial on writing your own:
https://css-tricks.com/creating-your-own-gravity-and-space-s...
I played with a simple program like that for the Amiga when I was younger, and then I discovered that there was an O(n log n) algorithm[1] rather than the obvious O(n^2) one. Never was up to writing a program to use it.
https://en.wikipedia.org/wiki/Barnes%E2%80%93Hut_simulation
https://en.wikipedia.org/wiki/Barnes%E2%80%93Hut_simulation
I highly recommend Space Engine
https://store.steampowered.com/app/314650/SpaceEngine/
I used it on an iPad.
For me, this was a beautiful example of how to leverage the strengths of a touchscreen to present information.
(too often, I find myself shaking my fist at how we’ve "bolted" a magazine onto a high-dpi display)
Wonderful stuff... thank you for making and sharing!
Wonderful stuff... thank you for making and sharing!
Very good made! I recently started astrophotography, it is a lot of fun. Just learning all those different stars and galaxies, it's incomprehensible how big is the space. Nice thing it's really doable to appreciate it live from your backyard. A lot of technical things are still desirable, a big opportunity for innovative ideas.
Wow. What a great explanation. I'd love it to be translated in other languages so I can have my younger kids spend some useful screen time on it!
Very well made and very educational!
An often used algorithm for the calculation of the apparent sun position (given a date and latitude/longitude of the observer) is SPA of Reda et al. [1]. If you're interested, I wrote an Android app (Sun Locator [2]) that implemented this algorithm.
[1] https://www.sciencedirect.com/science/article/abs/pii/S00380...
[2] https://play.google.com/store/apps/details?id=com.genewarrio...
An often used algorithm for the calculation of the apparent sun position (given a date and latitude/longitude of the observer) is SPA of Reda et al. [1]. If you're interested, I wrote an Android app (Sun Locator [2]) that implemented this algorithm.
[1] https://www.sciencedirect.com/science/article/abs/pii/S00380...
[2] https://play.google.com/store/apps/details?id=com.genewarrio...
This is what the web is for. Charming, intimate. Thank you
Very nice visualization. It'd be interesting to see it extended to the galaxy, as in https://www.physicsforums.com/threads/orientation-of-the-ear...
> The Earth rotates around its axis from west to east, or, when seen from above, counter-clockwise.
North is not up.
When seen from above the South Pole, the Earth is rotating clockwise.
But really doesn't make much sense to talk about the rotation of a sphere by analogy to a 2D clockface. The Earth rotates from West to East; that's all that needed to be said here.
North is not up.
When seen from above the South Pole, the Earth is rotating clockwise.
But really doesn't make much sense to talk about the rotation of a sphere by analogy to a 2D clockface. The Earth rotates from West to East; that's all that needed to be said here.
Dont all maps have north 'up's? I'm curious if there are maps that invert this.
An example of a south-is-up map: http://mapdesign.icaci.org/wp-content/uploads/2014/01/MapCar...
We're not talking about a map here, we're talking about the real thing, the Earth, hanging in space.
(But yes, there are many maps that don't have north at the top).
(But yes, there are many maps that don't have north at the top).
Your just using your preferred frame of reference.
It seems reasonable to call north up because that frame of reference is how maps usually look.
To subsume your frame of reference, we could say the Earth isn’t hanging in space, it’s in free fall around the sun.
There are other frames of reference at progressively larger scales.
Edit: Also, the word ‘hanging’ usually implies an ‘up’.
It seems reasonable to call north up because that frame of reference is how maps usually look.
To subsume your frame of reference, we could say the Earth isn’t hanging in space, it’s in free fall around the sun.
There are other frames of reference at progressively larger scales.
Edit: Also, the word ‘hanging’ usually implies an ‘up’.
> Your just using your preferred frame of reference.
No I am not. What I said was that they should have left it as just that the Earth rotates from West to East (no frame of reference). I only talked about how it would look like from above the South Pole to show that the described anti-clockwise direction of motion was relative to the frame of reference that was being, unnecessarily, assumed.
The Earth has two poles and they are equal, just like with any (approximate) sphere. If you are going to describe how the Earth's rotation looks from above one pole then you should also describe how it looks from above the other. But once you describe it from both poles it becomes obvious that you're not really imparting any useful information because, while it looks clockwise from above one pole it looks anti-clockwise from above the other. Better to not use any frame of reference at all. We know that the sun rises in the East and sets in the West. With just a little thought it is then obvious that the Earth is rotating from West to East and that is all that needs to be said.
No I am not. What I said was that they should have left it as just that the Earth rotates from West to East (no frame of reference). I only talked about how it would look like from above the South Pole to show that the described anti-clockwise direction of motion was relative to the frame of reference that was being, unnecessarily, assumed.
The Earth has two poles and they are equal, just like with any (approximate) sphere. If you are going to describe how the Earth's rotation looks from above one pole then you should also describe how it looks from above the other. But once you describe it from both poles it becomes obvious that you're not really imparting any useful information because, while it looks clockwise from above one pole it looks anti-clockwise from above the other. Better to not use any frame of reference at all. We know that the sun rises in the East and sets in the West. With just a little thought it is then obvious that the Earth is rotating from West to East and that is all that needs to be said.
> Better to not use any frame of reference at all.
Ok
> We know that the sun rises in the East and sets in the West.
You didn’t even try!
Ok
> We know that the sun rises in the East and sets in the West.
You didn’t even try!
Frankly, it's pathetic that you play games with the words I use - 'hanging', 'rises' - which everyone understands are not actual descriptions of reality and don't engage with the argument at all, which is about reality.
You started it:
> North is not up
> North is not up
You remain blind to, either willfully or unconsciously, my argument. Instead you come back with puerile rejoinders.
Look at the original quote from the article - "when seen from above". There was an assumption there that seen from above means seen from above the North Pole. Thus an assumed frame of reference when none was needed.
I do not assume seeing the Earth from above means seeing it from above the North Pole. Neither would an astronaut, who don't have to assume, they live the experience of seeing the Earth from all orientations.
Look at the original quote from the article - "when seen from above". There was an assumption there that seen from above means seen from above the North Pole. Thus an assumed frame of reference when none was needed.
I do not assume seeing the Earth from above means seeing it from above the North Pole. Neither would an astronaut, who don't have to assume, they live the experience of seeing the Earth from all orientations.
I can’t upvote this enough. Beautifully crafted website
Last couple of months I started thinking about sidereal vs. solar year. The first one is determined by distant stars, the second one by our Sun.
The thing I'm thinking of is if small deviations accumulate over years, how night sky is changed at the same date across, let's say, 20 years?
The thing I'm thinking of is if small deviations accumulate over years, how night sky is changed at the same date across, let's say, 20 years?
If you think that can get complicated, check out the different global geodetic reference systems. Between the Earth's precession, plate tectonics, the Earth changing mass cyclically (collecting space debris and off-gassing atmosphere), and the fact that the center of our planet is a freaking wobbly blob of molten iron, well, things can get tricky.
Then there are the different eliosoidal (and soon geoid with NVD22) shapes that are the basis for every other reference system, most based on similar, but slightly different geodetic network adjustments. Some systems, like NAD83, remain relatively fixed in reference to a particular land mass (North America Datum 1983). Some will then progress with the land mass as it moves on the Earth's plates, others will remain fixed based on a (the) prime meridian, or in reference to the center of gravity of the Earth as it shifts, or in reference to Polaris, etc.
So now you have multiple measuring systems each referencing different geometric/geodetic/astronomic points/lines, and further it matters what time it was when you defined those points/axises. WGS80 is the basis for many modern systems, including NAD83. ITRF is similar, but defines a yearly amount of progression since ~1980 to account for things like continental drift. They coincided around the time when they were defined, and have been diverging some number of millimeters per year since then.
Once you agree on a definition of a system, you further have to define how to measure it. Will North be a point in time, or a rolling average? Will the center of gravity of the Earth be based on changing rate of Earth's rotation, or with respect to a geodetic benchmark or network, or maybe based on millimeter fluctuations in deviations of the orbits of the NAVSTAR / GPS satellites? Should Euro/ Chinese/ Russian / Indian versions of GPS satellites be taken into account?
I'm over simplifying things, as there are additional layers of complexity involving the actual tools for surveying and measurement, the precise steps for any network adjustments or translations, rounding rules and certain geometric assumptions made for different types of math, and way, way more. (You can't actually stretch a tape measure around the equater.)
Take all of that, and then contemplate how all of this is spinning around arbitrarily in space. Sidereal vs solar is only one of 100s of aspects of how we measure these things. It's not just time, but also geometric space.
Everything's relative.
Then there are the different eliosoidal (and soon geoid with NVD22) shapes that are the basis for every other reference system, most based on similar, but slightly different geodetic network adjustments. Some systems, like NAD83, remain relatively fixed in reference to a particular land mass (North America Datum 1983). Some will then progress with the land mass as it moves on the Earth's plates, others will remain fixed based on a (the) prime meridian, or in reference to the center of gravity of the Earth as it shifts, or in reference to Polaris, etc.
So now you have multiple measuring systems each referencing different geometric/geodetic/astronomic points/lines, and further it matters what time it was when you defined those points/axises. WGS80 is the basis for many modern systems, including NAD83. ITRF is similar, but defines a yearly amount of progression since ~1980 to account for things like continental drift. They coincided around the time when they were defined, and have been diverging some number of millimeters per year since then.
Once you agree on a definition of a system, you further have to define how to measure it. Will North be a point in time, or a rolling average? Will the center of gravity of the Earth be based on changing rate of Earth's rotation, or with respect to a geodetic benchmark or network, or maybe based on millimeter fluctuations in deviations of the orbits of the NAVSTAR / GPS satellites? Should Euro/ Chinese/ Russian / Indian versions of GPS satellites be taken into account?
I'm over simplifying things, as there are additional layers of complexity involving the actual tools for surveying and measurement, the precise steps for any network adjustments or translations, rounding rules and certain geometric assumptions made for different types of math, and way, way more. (You can't actually stretch a tape measure around the equater.)
Take all of that, and then contemplate how all of this is spinning around arbitrarily in space. Sidereal vs solar is only one of 100s of aspects of how we measure these things. It's not just time, but also geometric space.
Everything's relative.
Also, you can try to explain this to people, most of whom will complain that it's way too complicated, and we don't need anything to be that precise. They say it's ridiculous.
Then you can ask the same person for directions to their house, and they'll turn around and text you GPS coordinates to 12 digits.
Then you can ask the same person for directions to their house, and they'll turn around and text you GPS coordinates to 12 digits.
This is excellent. I had been wanting to see something like this for a long time. It was difficult for me to imagine the orbit of earth around the sun, and nothing I found showed it well. Thanks for making this!
Amazing how he got the clouds to stand still for an entire year :)
This is excellent. Are all the interactions custom made?
This is so excellent. Put it on school curricula!
Excellent visualization of these astronomy concepts, amazing job, my sincere congratulations!
I’m not sure if it’s related but I can’t seem to understand the international date line.
The international date line is needed when you use local times instead of UTC, because the local date is incremented on midnight local time. So, if it's October 19 just after your local midnight, every timezone to the east should also have October 19, while every timezone to the west should still have October 18 because they haven't had local midnight yet. But that doesn't work, since east ultimately meets west when you track both directions far enough. So by convention we have defined a line (or rather a crooked boundary between timezones) where the date jumps back a day in the calendar when you pass over it in an eastwards direction.
Thanks but that much I understand. I guess for people living in that border it doesn’t make sense to me how they can jump back and forth 24 hours.
really good, I wonder if there's a "Earth and Moon"?
If you would like to make it yourself, check out my library! https://github.com/ryanseys/lune
Are all the interactive infographics custom made? Amazing.
wow. Excellent read. much respect. Labor of love.
This is the best I've seen till date;
This was fantastic! Thanks!
Excellent work!
this is wonderful
This is a personal reflection on the way it's presented. I'm sure that there are people who already know some of the content, and I found myself skimming over things, nodding, and thinking "Nothing new here." Then realised that there was something I missed, or an explanation that was especially nice, and I had to go back and re-read, wondering what else I might have missed.
So I found it all very smooth, clean, informative, but there was no story, no arc, no narrative, nothing to make me want to sit with a coffee (or other beverage of choice) and simply read like a novel. There wasn't the "Hook; Narrative; Reveal" structure that keeps the reader involved.
Which is a bit of a shame, because the bits I did take time over are really, really nice.
It's really nice.