Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Combining 15s interval whole-sky-camera photos to form a 4y spanning keogram

astrodon.social

Post reply on HN
Print view View original

61–70 of 93 posts

Re: Combining 15s interval whole-sky-camera photos to form a 4y spanning keogram

#61

Post by dylan604 »

crazygringo wrote: post #59
dylan604 wrote: post #57

Earlier quoted context omitted.

And exactly how does that help the specific narrative?

You were writing as if people were staring at the sky all night long out of boredom. You said "There was really nothing else to do." That's completely untrue. It's a total misunderstanding of what life was like. I'm not helping your narrative, I'm saying it's a false narrative. We have so many misunderstandings about how people used to live, it's important not to perpetuate them.

Everything you listed as options to do are also available now, yet people still choose to stay home and look at their devices. Pedantry for pedantry sake is just boring

Re: Combining 15s interval whole-sky-camera photos to form a 4y spanning keogram

#62

Post by hinkley »

azepoi wrote: post #58
hinkley wrote: post #52

My favorite work in this vein is still the guy who did the trigonometry to convert a year+ worth of telemetry from a light level sensor in his back yard to paint a picture of the tree canopy. Each day is a scan line of light and dark patches at a different solar inclination. So everything above the sensor eventually got “painted”.

Have you got a link or do you remember the name of this person?

Oh gosh it's been a while. I thought it might have been in r/dataisbeautiful but I'm coming up with nothing. I have a vague recollection of what the picture looked like but search isn't turning it up.

Re: Combining 15s interval whole-sky-camera photos to form a 4y spanning keogram

#63

Post by crazygringo »

dylan604 wrote: post #61
crazygringo wrote: post #59

Earlier quoted context omitted.

You were writing as if people were staring at the sky all night long out of boredom. You said "There was really nothing else to do." That's completely untrue. It's a total misunderstanding of what life was like. I'm not helping your narrative, I'm saying it's a false narrative. We have so many misunderstandings about how people used to live, it's important not to perpetuate them.

Everything you listed as options to do are also available now, yet people still choose to stay home and look at their devices. Pedantry for pedantry sake is just boring

> Everything you listed as options to do are also available now

That has no bearing on anything you or I said.

> Pedantry for pedantry sake is just boring

Perhaps you don't understand what pedantry is? Your entire point was a false description of what humanity was like. Just take this as a learning experience! :)

Re: Combining 15s interval whole-sky-camera photos to form a 4y spanning keogram

#64

Post by imoreno »

This is neat, but the amount of data seems overkill just to see the trend in day/night length and the keogram is a bit busy. It seems like compressing each day to 1 px tall would result in a clearer representation of that.

It's neat that you can look at different things, like cloud cover, the moon, stars and anomalies (such as the aurora). But these are convoluted in the raw data. Deconvoluting these to obtain a keogram of just the sun, just the moon, just the anomalies would probably make for some interesting visualizations.

Re: Combining 15s interval whole-sky-camera photos to form a 4y spanning keogram

#65

Post by gregfjohnson »

This brings to mind something I've wondered about for a while. Sunrise on the shortest day of the year is earlier than sunrise for several days after it.

Sunset on these days after the shortest day is of course even later than sunset of the shortest day.

On the beautiful image of the OP, you can see that after dawn of December 21, dawn continues to get later over the next few days.

In my area, sunrise on 12/21/2024 was 6:54am, and it will continue to get later until 1/8/2025, when it is at 6:59am.

Length of day on 12/21/2024 is 9 hours, 54 minutes, and length of day on 1/8/2025 is 10 hours, 2 minutes.

Searching the web, I haven't found an explanation for this that "clicks" for me as both intuitive and rigorous. Any thoughts or pointers on this?

Re: Combining 15s interval whole-sky-camera photos to form a 4y spanning keogram

#66

Post by mjbrownie »

bikamonki wrote: post #49

So cool that the shape resembles an hourglass!

I work with a shorebird expert who has been tracking migrations (Latham snipe whose range extends from Russia/Northern Japan to Southern Australia).

I think an early technique of tracking their migration before gps/chip/batteries were small enough was a primitive light sensor + data logger that would log day/night hours on the bird as it flew from island to island and the light data was enough to roughly estimate lattitute (and often enough to infer a location/date.

The data looked great in this form. It wasn't hourglass but with jagged edges and shifts. You could easily see which months the bird stayed in a single place for several days etc. clever stuff.

Re: Combining 15s interval whole-sky-camera photos to form a 4y spanning keogram

#67

Post by raimondious »

gregfjohnson wrote: post #65

This brings to mind something I've wondered about for a while. Sunrise on the shortest day of the year is earlier than sunrise for several days after it. Sunset on these days after the shortest day is of course even later than sunset of the shortest day. On the beautiful image of the OP, you can see that after dawn of December 21, dawn continues to get later over the next few days. In my area, sunrise on 12/21/2024 w…

I don’t know if this is sufficient but there was just a StarDate about the topic https://stardate.org/podcast/2024-12-3

Re: Combining 15s interval whole-sky-camera photos to form a 4y spanning keogram

#69

Post by incognito124 »

gregfjohnson wrote: post #65

This brings to mind something I've wondered about for a while. Sunrise on the shortest day of the year is earlier than sunrise for several days after it. Sunset on these days after the shortest day is of course even later than sunset of the shortest day. On the beautiful image of the OP, you can see that after dawn of December 21, dawn continues to get later over the next few days. In my area, sunrise on 12/21/2024 w…

The apparent movement of the sun is not influenced solely by the Earth's rotation, but also the instantenuous velocity of revolution and also the fact that Earth's axis is slanted w.r.t. the ecliptic.

Study this Wiki article, especially the components part: https://en.wikipedia.org/wiki/Equation_of_time

Re: Combining 15s interval whole-sky-camera photos to form a 4y spanning keogram

#70

Post by incognito124 »

russellbeattie wrote: post #60
gmiller123456 wrote: post #50

You've got much better weather than we do. Here's mine from near Louisville KY (from Aug 2023 to Aug 2024) https://www.facebook.com/groups/101640086556073/posts/794426...

It's easy to forget how far north Europe is! The daytime vs nighttime hours is so much more extreme there. The Netherlands is on the same latitude as Newfoundland in Canada. I noticed the extreme hour glass shape in his image, but it's even more impressive when compared to yours!

I always forget how south the US is. Rome is approximately at a similar latitude like Boston!
Post reply on HN