Tuesday, May 17, 2022

Superb example of SearchResearch... in Algeria

 I have a wonderful video I want to recommend to you.  It's about what this mysterious circle of circles is... 



In this video from Vox, they explore the limits of what you can find by internet searching, and go beyond the limit when they realize that they'll have to visit this site in person.  It's not exactly around the corner: it's at 27.270161, 4.322245, which is, you'll quickly realize, in the middle of the formidable Algerian desert.  

The key question is: When / what / who made these circles in the (literal) middle of nowhere? 

I didn't expect to watch this entire video, but it is well worth the time.  In it, the researchers do all of the things you'd expect from a SearchResearch Challenge (finding original sources, locating experts, contacting them, etc).  It's a wonderfully produced video that lays out their research process step-by-step.  Check it out, and tell me if you're not pulled into the mystery after the first 30 seconds.  

Bravo, Vox!  Bravo!  

Vox's video: Who made these circles in the desert?  




Search on!  


Wednesday, May 11, 2022

SearchResearch Challenge (5/11/22): Why... in New Orleans?

 This past week I was in New Orleans... 

... that fabled city along a bend of the Mississippi, home to classic jazz, crawfish etouffee, po boy sandwiches, and a confluence of many cultures from around the world.  

It's a colorful place with a long and complicated history, and for this traveler, a nearly endless source of great SRS questions.  Here are two that popped up for me this past week.  Can you help me figure them out?  

1. One of the great symbols of New Orleans are the steamboats that used to ply the river. They're wedding cakes on the water, full of color, decoration, and outsized components.  They don't use propellers, they use giant paddlewheels driven by large steam engines.  One of the most noticeable parts of a traditional steamboat are the smokestacks.  In this image of the Natchez  riverboat "City of New Orleans," you can see that the top of the smokestack ends in an incredibly elaborate patterning at the very top.  Since you see this kind of thing on nearly all steamboat smokestacks, that made me wonder--is that patterning at the top purely decorative, or does it have some kind of function?  What can you find out? 



2. While New Orleans is a generally colorful place, three colors seem to dominate: purple, gold, and green.  Is this color scheme really a thing?  Or am I making a vast overgeneralization?  



3.  There also seems to be an awful lot of fleur de lis in the decoration of New Orleans, you see them absolutely everywhere (including between the smokestacks above!):  Why?  




As always, be sure to tell us what you found out.. and HOW you found out!  (Tell us your process and citations.  We want to learn from you.)   

Search on!  


Tuesday, April 19, 2022

Answer: Why water the astroturf?

 It's true!  

This IS a picture of the University of North Carolina very actively watering an artificial turf.  I took this pic one sunny afternoon not long before the field hockey team was about to take the field.  Of course, this struck me as nonsensical, but when you see things that seem truly odd, there's usually an explanation. That's this week's Challenge... 

Why?   

This week's Challenge: 

1. Why do they water the artificial grass before (and sometimes during) a game?  

In this case, when I was there I spotted the groundskeeper who was actually running the sprinkler and monitoring how well they were doing.  Being a curious sort of fellow, I walked over, struck up a conversation and asked "Why are you watering the artificial grass?"  His reply:  "We do it a couple of hours before the game to make sure the field hockey balls (or lacrosse balls) won't run quite as far when they hit the surface.  If it's dry, they move fast and run off the field too quickly... which is a hassle."  

So, his answer: To increase the drag on the ball.  He helpfully pointed out that on "hot days, we'll water the field during halftime for the same reason."  

That's probably correct, but naturally, I was interested if there was any other reason.  So I started my reading with: 

     [ field hockey water on surface ] 

and found several good results.  The UK's Express sports page says that "The artificial playing surface is actually watered on purpose before each hockey game in order to improve play. GreenFields, an artificial turf systems company, said: 'The pitch is fully irrigated with a layer of water which results in an extremely fast and professional game.'"  

Interesting.  That's not what the groundskeeper said.  He said the reason is to have the balls move more slowly.  

Greenfields goes on to say that "During a hockey match, an average of 6,000 litres of water is used to irrigate the pitch. This is enough drinking water for a 3-person household for 6.5 years!"  (That's enough water to cause this Californian to pause.)  They also go on to say that the reason for watering the field is to "lower the surface temperature" to something more like natural grass.  

Looking around at other results I find that Halloran and Yauch (an irrigation systems company) say that watering an artificial field can: 

a. lubricate the surface to reduce injuries; 

b. cools the surface to reduce rug burns; 

c. stabilize the surface to add to field life; 

d. keeps the surface moist to prevent the synthetic fibers from breaking.  

Similar arguments are made by the TigerTurf company (another artificial field provider).  

On the other hand, searching for: 

     [ water on artificial turf soccer ] 

leads me to several other articles that repeat the "cooling" story, but also to an article (ParksAndRecBusiness) pointing out that for the special case of field hockey, water on the astroturf provides "“Uniform ball bounce and a non-directional roll..."  

Sounds like the PRIMARY reason is for this extravagant field watering is to make the field cooler--that makes sense, especially in places like North Carolina, which can get mighty warm.  There's also probably a more consistent ball rolling behavior with water on the field, which might be slower, might be faster, but certainly more predictable.  

Lest you think this is only an issue in places with lots of water, what kind of water you use on an artificial field matters--it's supposed to be potable water.  So, in LA, the question comes up, does watering an artificial field use less water... or more... than natural grass.  I will leave this as an open question for rabid sports fans to answer.  

Where the stick hits the watery field...


2. In what other sports do they water the field before (and sometimes during) a game?  Why do they water those fields?  

I did a generic search by: 

     [ "spray * on * field" sports ] 

to find all mentions of spraying something (the first *) onto something followed by "field."  I added sports to the query to get rid of results talking about spraying on agricultural fields.    

And, I found what you'd expect: that they spray water on baseball infields (which are usually red clay, which gets mighty dusty), and they spray water for the same reason on horse-racing tracks.  Of course, I also found many articles about spray-painting logos onto artificial turf for both permanent markings (e.g. lines), but temporary markings (e.g., for visiting team logos).  

But the biggest surprise in these results was the observation that sometimes you need to spray artificial grass with weed killer!  This led me to do a special search on: 

     [ spray herbicide on artificial grass ] 

and discover that it's recommended to use a herbicide twice a year to control those pesky weeds that can even grow... on an artificial field.  


SearchResearch Lessons

It's often a really good idea to talk with people in the field when you've got a SearchResearch question.  This is especially true when they're engaged in the activity that's piqued your curiosity.  But as good as that is, there might be a deeper story to discover.  That's why I always: 

1.  Trust, but verify.  The conversation is often a great place to begin your SearchResearch.  But even people who are doing something might not have the full story.  Sometimes they do--but it's a great starting point.  (And who knows, you might make a friend.)  

Search on! 



P.S.  I'll be away for the next two weeks, heading off on an actual vacation.  You can guess that there will be more SearchResearch Challenges in the near future that draw upon what I see there.  Details when I return.  But don't take two weeks of quiet as me being MIA--it's just time for a bit of a break.  The Challenge will return on May 11.

 

Bula vinaka!  


Wednesday, April 13, 2022

SearchResearch Challenge (4/13/22): Why water the astroturf?

 I couldn't believe my eyes!  

As a native Californian, I'm sensitive to water use and I'm drawn to extravagant displays of water.  Waterfalls attract me, rivers and even creeks capture my attention. (And you know I love the sea.)  

So as you might expect, seeing large fountains of water being sprayed onto an athletic field in midday caused me to watch in admiration as these powerful jets rocketed vast quantities of water onto the field. 

But wait a second... That turf is remarkably green, smooth, and oh-so-perfect.  

Naturally, curiosity made me wonder about the reality of the grassy field.  As I was walking across campus, I had a few extra minutes, so I took a detour and wandered down to the field to see what was going on.  Much to my surprise, I found that it's an artificial field!  Can that be real? Are they really putting a LOT of water onto fake grass?  It didn't add up.  

The question here is obvious... Why water the astroturf?  

A big part of my curiosity engine is to keep asking about what it is I'm seeing. Does what I'm seeing make sense?  Why is the land like that?  Why are people standing in that line?  What's going on with the plants / animals / fish / water... 

As it turned out, a groundskeeper was monitoring the sprinklers, so I was able to walk over and chat with him for a few moments and ask him the question.  His answer surprised me--and perhaps it will surprise you as well.  

As a Californian, I'm still stunned that this university in North Carolina would put so much water onto a surface without any plants, but NC doesn't exist in a state of drought.  In fact, the day before this photo was taken, it was raining very, very hard--one of those hard, tropical rains--which only made the field watering seem weirder.  

This week's Challenge: 

1. Why do they water the artificial grass before (and sometimes during) a game?  

2. In what other sports do they water the field before (and sometimes during) a game?  Why do they water those fields?  

As usual, I'm curious in what you learn in your search... but I'm VERY interested in how you found the answer.  What was your SearchResearch process?  

But most of all... why on earth would you water artificial grass?

Search on!  

Wednesday, April 6, 2022

Answer: Where is the oldest solar observatory in the Americas?

 Watching the sun... 



... is something that humans have done since we noticed that it traces out a pattern in the sky over the course of a year.  Of course, it's much easier to do this if you live on an open plain, where it's obvious that the sun sets and rises in a slightly different place each day.  As mentioned, Stonehenge is famously aligned with the solstices and seems to have been used as a large astronomical calculating device.  (Although how anyone in central England had enough clear and sunny days to make the calculations is actually beyond me.)  

But our curiosity also runs to solar observations made in the Americas.  What about the New World?  When did similar solar observations start here? 

That was the Challenge--can you find out? 

1.  When was the first observatory for sun-watching purposes created in the Americas?  Can you find out who made it?  Where is it?  And what happened to those people?  

I, like many of you, started with a simple, pointed query: 

     [ first solar observatory Americas ]


If you read those stories carefully, you'll find they all point back to an article published in Science (and VERY high reputation journal) Ghezzi, Ivan, and Clive Ruggles. "Chankillo: a 2300-year-old solar observatory in coastal Peru." Science 315.5816 (2007): 1239-1243.  (Link to full-text of the paper.) 

The observatory dates to the 4th century BCE, or about 2300 years ago.  It's 9 miles from the Pacific ocean on the eastern slope of a wide plain that gives a great 360 view of sunrises and sunsets.  It's a place without many trees, a place where you'll learn what the sun does every day of the year.  It's easy how one might come to view the sun as a god-figure.  We know that the Inca revered the sun and built astronomical temples (e.g., Machu Picchu), but learning about this site made me wonder about the relationship between the people who built Chankillo (the Casma/Sechin culture) and the Inca.  

In the above interview with NPR, the first author, Ivan Ghezzi said that: 
"We know that the Incas made powerful political statements based on the relationship between the sun and the king... The Inca claimed to be the offspring of the sun. But now we have a society that is 1,800 years before the Inca that is clearly using the sun as a way to make a political, social and ideological statement."
The Casma/Sechin culture is amazing--they began around 3200 BCE and stopped around 200 BCE.  There's not a lot of information about what followed the Casma/Sechin people; they seemed to be invaded by people from the mountains and just vanished into the mists of time as the Early Horizon (900 – 200 BCE) era ended... right around when Chankillo was built, and then abandoned.  

The Inca, meanwhile, date from 1438-1533, just under 100 years.  How is it possible that I didn't know about a pre-existing culture that lasted for 3 millenia?  I'm sure I'll be reading more about this remarkable culture in the weeks ahead.  (The Incas and Their Ancestor:  The Archaeology of Peru.  Michael Edward Moseley. 2001)

The Chankillo site itself is full of fascinating things.  You can even use Google Maps to get a look at the site from the satellite images.  The 13 pinnacles are arrayed on the back of a low ridge, looking like vertebrae that have been cut out of the stone:   

Closeup view of the observatory ridge.  P/C Google Maps

If you zoom out, you can see that there's evidence of a LOT of other buildings and sites all around the area. 

View from above.  P/C Google Maps

The chankillo ridge with 13 notches, looking towards the mountains in the east. 
P/C Google Maps

Most impressively, there's a large temple/fortress complex just to the west.  This is interpreted as being a temple with defensive capabilities--a suggestion that even 2300 years ago, battles were being fought in this part of Peru.  (There's some debate about whether these were actual battles or ritualized fights--whatever the actual interpretation, building this site was a lot of work in difficult environment.)  

Nearby fortified temple site (P/C Google Maps)

A great shot of the ridge.  P/C Wikimedia, by David Edgar (2013)

As Remmij pointed out, there's a GREAT video tour of the Chakillo site: If you're interested, check it out. 




One of my goals was to quickly get a sense of the surrounding literature about Chankillo.  My favorite way to do that is to find the most authoritative article (in this case, the original article in Science by Ghezzi and Ruggles), and then use Google Scholar to see what other works cite this paper.  That is, I did this--searched for the paper in Scholar, and... 


Which then gives me a list of other publications that cite this original work, usually extending it or giving new interpretations: 



I then just opened a bunch of these papers in parallel ("lateral browsing") and then scanned through them, picking out the ones that were interesting and/or relevant to my interests.  

SearchResearch Summary 


1.  When you're curious about something, take a look!  In this case, Google Maps (or other aerial image sources, as we've discussed) can be a great resource for furthering your curiosity.  

2.  Looking "around" a topic can be done by looking at other works that cite the work that's most like what you're interested in.  I tend to use the "Cited by" link in Google Scholar as a great way to look around.  This won't give you news accounts, but it does link you to some of the surrounding literature that can teach you a great deal.  (In my case, I'm going to start running down the mysterious Casma/Sechin culture!  



Search on! 

Wednesday, March 30, 2022

SearchResearch Challenge (3/30/22): Where is the oldest solar observatory in the Americas?

We all watch the sun... 


... sometimes with sunscreen, but nearly always at sunrise and sunset.  We notice when the days grow shorter or longer, and as we've seen in earlier SRS Challenges, it's an endless source of fascination for people, shadows, and the time of year.  

Since we've talked about the patterns that the sun makes in the sky, it got me to wondering, when did people first start keeping track and building observatories?  We know that Stonehenge, those marvelous circles of stone and ridges of earth in England, was built between 3000 and 1520 BCE.

What about the New World?  When did similar things start here? 

That's today's Challenge--can you find out? 

1.  When was the first observatory for sun-watching purposes created in the Americas?  Can you find out who made it?  Where is it?  And what happened to those people?  

This Challenge isn't hard, but when I found the answers, I was a bit surprised.  And naturally, once I started learning about these things, this led to further questions as I followed my curiosity a bit.  

I'm curious now: What else did you find interesting to seek out?  What did this Challenge prompt you to go learn about?  

Curious is as curious does.  Where does all this take you?  

Tell us your stories in the comments below. 

Happy observing! 

Search on! 

Wednesday, March 23, 2022

Answer: Finding the connections?

 How is this like that? 

.

Seems to me that noticing how ideas, people, places, and words all link together is a fundamental to creative thought.  

Last week's Challenge was an example of this kind of connective thinking, one that I hope leads you to learning how to find your own fascinating connections.   

Backstory:  I was walking along a trail that follows the edge of an oceanside bluff in a place that has wind and weather that always comes from the same direction.  In this case, the winds always come out of the west, flows over the bluff, and then blows constantly on the trees and shrubs at the top of the cliff.  As you'd expect, this causes some pretty serious deformations in the way the trees grow.  The tree shown above was especially bent and pruned by the wind, as are most of the trees along this part of the coastline.  

That walk led to today's Search Challenge: 

1. If I want to learn more about such bent and deformed trees, what's the specialized search term that I'd want to use?  (Hint: There is a very specific term to describe such trees--that's what you seek.)  

Where do you start with such a Challenge?  In my case, I suspected that there would be a specialized term about such trees--and as we know, if you have a precise term for something you'd like to find, it makes your search (and your corresponding learning) that much simpler.   

My first search was: 

     [ tree bent over by wind ] 

and after scrubbing through the results (and NOT finding anything useful--just lots of information about how to straighten up bent trees), I tried a more direct route: 

     [ word for tree bent over by wind ] 

and--lo and behold--the first result was exactly what I was looking for.  


Of course, once I learned this, I did a few followup queries to make sure that I understood what krummholz really meant.  As the Wikipedia excerpt suggests, it has a connotation of being a tree at a subarctic or subalpine place.  But as I looked around, it's clear that the term is used more broadly to include all kinds of trees that are bent over, pruned, edited, or otherwise shape-shifted by wind and weather.  

2. What is the name of a musical instrument that sounds a lot like this specialized term?  (Hint: The word for the instrument shares a language of origin and the first 6 letters with the tree-term.  This is one of those "you'll know it when you see it" kinds of Challenges.)  

Now that we know the term krummholz, I did this : 

     [ krummholz musical instrument ] 



I'm not quite sure what I expected, but the spelling suggestion of "krummhorn" is great!  

When you look up krummhorn, it's quickly clear what the connection is: 



A krummhorn (also spelled crumhorn) is a bent wooden instrument.  "Krumm" is the German term for "bent," so it is literally a "bent horn."  Interestingly, from the Wikipedia entry we also learn that this term is still a part of English as heard in the term "crumpet" (a curved cake) and "crumpled" meaning a bent piece of material, as in "he crumpled the piece of paper..."  

"So", my wondering mind thinks, "is the crumhorn made from a bent piece of wood?  If so, how would they drill a curving hole?"  

A quick query solves that question:  

     [ how to make a krummhorn ] 

which leads to a fantastic video of the production of a krummhorn.  Answer:  The wood is initially a straight cylinder, which is drilled through, and then steamed and bent into the final curved shape.  It's worth watching this video to see how the krummhorn comes to be: 



What's remarkable is how quickly the tube is bent from straight to curved--just a few seconds!  

Regular Reader Mathlady had a slightly different approach to the Challenge--her query was [ krummh musical instrument ] which gave her this result: 



Notice that in this case the Google spelling corrector kicked in on the partial word "krummh"--when Google asks (in the red text above) "Did you mean:" that's a spelling correction.  Fortunately, the word krumm is a legitimate German word (meaning "bent"), and all of the results feature "krumm" (as in "krumm horn") the instrument we seek!  

My last query was to YouTube for krummhorn, which led me to this wonderful video showing what a krummhorn is, how it works, and how it sounds in a trio consort of krummhorns.  Worth a watch: 





SearchResearch Lessons 


1.  Pay attention to suggestions and spelling corrections!  When searching, as in horseshoes and hand grenades, close is often good enough.  If you watch the Google spelling corrections and the suggested searches, you can often recognize a better version of what you're searching for--keep a weather eye open to the nearby alternatives!  

2. Once you have an answer, play around a bit and learn some of the surrounding context.  We could have framed this Challenge as simply "what's the bendy tree called?" but then we wouldn't have noticed the connection to these wonderful Medieval instruments (or learned the German word for "curved").  There's no end of fascinating things to learn, and interest-driven learning is the best.  

Stay curious, my friends!  

Search on! 



Wednesday, March 16, 2022

SearchResearch Challenge (3/16/22): Finding the connections?

 Finding connections... 

.

.. is a good part of what I do in my day-to-day work.  As a professional researcher, I often look at data and try to figure out what this data is telling me, and how it connects to other things I know about. In particular, I try to understand how X connects (or influences) Y.  That's sort of science in a nutshell--how do things connect?  

Here's an example of this kind of connective thinking that occurred to me the other day.  

I was walking along a trail that follows the edge of an oceanside bluff in a place that has wind and weather that always comes from the same direction.  In this case, the winds always come out of the west, flows over the bluff, and then blows constantly on the trees and shrubs at the top of the cliff.  As you'd expect, this causes some pretty serious deformations in the way the trees grow.  The tree shown above was especially bent and pruned by the wind, as are most of the trees along this part of the coastline.  

As you can see, it leans away from the wind and rain coming off the bluff (which you can barely see falling away into the sea on the far left).   

While walking past this tree, I wondered today's Search Challenge: 

1. If I want to learn more about such bent and deformed trees, what's the specialized search term that I'd want to use?  (Hint: There is a very specific term to describe such trees--that's what you seek.)  

And, as I was thinking about that term, I realized that it made a connection to a musical instrument, also made of wood, that uses the same bit of language in its name.  The moment I realized this, I understood the connection!  This leads to the connecting Challenge: 

2. What is the name of a musical instrument that sounds a lot like this specialized term?  (Hint: The word for the instrument shares a language of origin and the first 6 letters with the tree-term.  This is one of those "you'll know it when you see it" kinds of Challenges.)  

I don't think this is too hard, but it's fun to find connections between very different parts of one's life (in my case, a connection between botany and music).  

Let us know how you did.  Next week I'll talk about what I did to figure out this connection.  

Search on!  


Friday, March 11, 2022

Answer: What are some good (almost) real-time satellite image sources?

  Seeing the Earth from space... 




... is a truly remarkable ability. It literally changes your perspective.  What's even better, in these days of ever-cheaper costs to fly a satellite, and the increasing capabilities of small satellites, space images are becoming easier (and cheaper) to get. 

The Challenge for last week was to find good aerial or satellite images that are more-or-less in realtime.  As you can appreciate, the big problem is getting your hands on current images--or at least accurately time-stamped images from the not-too-distant past.  Getting near-real-time imagery would be great, but often that's outside the budget of many non-professional searchers. 

So today's Challenge is a kind of collective ask for all people who do SearchResearch: 

1. What are the best resources to get time-stamped satellite images?  How can an ordinary SearchResearcher get their hands on satellite images not very long after (or even during!) a major event?  

When faced with a problem like this, I usually start with my "list of" trick, beginnings with a search like this: 

     [ list of satellite image providers ] 

and sure enough, this gives a set of web pages that have long lists of potential sources (even including 4 ads at the top of the SERP pointing to commercial sources).  One of the more useful results here is "15 Free Providers" with links to several satellite image services.  (And, to tell the truth, I was expecting to find something like this on the results page.)  

Naturally, if you've got a bunch of sources like this, my natural inclination is to organize them on a Google Spreadsheet.  Not only does the sheet put everything I find into a single location, but as I read through the results, I'll find different properties of the image providers that I might want to sort or filter.  

Here's that spreadsheet.  Enjoy it. (And let me know if you find any errors.)  

I started just by collecting the links to many different providers.  Then, for each one, I explored a bit about what they offered, what they're good at, and the considerations to keep in mind.  

I found that the tradeoffs are always the same: cost (you can get nearly anything if you want to pay), resolution, and timestamps.  

That is, it's easy to get free low-res images without a particular time-stamp (such as by using Google Maps, Bing Maps, or Google Earth).  But if you're looking for images from one specific date (especially if it's recent), then you'll need to use one of the providers that gives you fine-grain control of your imagery.   

Examples: See Iroquois Reef--this place is under contention because of Chinese ships landing on/near the reef.  So, how can we monitor it?  One answer: Use DigitalGlobe (Maxar product) to select the image and time that matches your need: 

Iroquois Reef (P/C DigitalGlobe)

No fishing boats in sight on this Feb 27, 2022 image.  But if you look around in the Spratley Islands, fishing vessels aren't hard to find.  Here I used Google Earth to spot 7 fairly large ships anchored just west of Jones Reef (click on the image to see it enlarged):  

Jones Reef with ships in view (P/C Google Earth)

The big difference here is that while the Google Earth is a great satellite image, the only time/date information is that this image comes from Maxar, 2022.  (Google Earth aggregates many sources of satellite imagery, including Maxar.)  But if you go to DigitalGlobe, you can get the specific date of the image.    

Here is another pair of images of the Oxley area of Brisbane, Australia.  You can see the extent of flooding in the brown patches (previously green areas flooded by brown, silty water).  Both of these images are also from Maxar's DigitalGlobe.  

Brisbane Oct 27, 2021 (P/C DigitalGlobe)

Brisbane Mar 6, 2022 (P/C DigitalGlobe)



Another useful provider is the SentinelHub's Playground website.  You can quickly scrub through different parts of the world and select images by date.  Below is an image from Kiev taken on Feb 26, 2022.  (If you do this and look at the images from nearby dates, you'll quickly find out how many days Kiev is covered in clouds! It's hard to get a clear view.)  This is at 10m resolution, not great for seeing much detail, but at least we know what date this image was created.  

Kiev as of Feb 26, 2022 (P/C Sentinelhub Playground) 


However, sometimes you can find public images that are shared as part of a special series or collections.  Example: Soar has a wonderful collection of images, including this great high-res image of downtown Kiev as of Feb 28, 2022 Note that this isn't part of their usual image set (which is at much lower res), but a special collection.

St. Sophia Square, Kiev, Ukraine (Feb 28, 2022--30 cm resolution). P/C Soar.


You can see the differences in the images and resolution by comparing several different sources of the same (well-known) location.  Here are the pyramids as seen by different providers.  

Pyramids (P/C Google Earth on web browser)

Pyramids (P/C Bing Maps) 


Pyramids (P/C Mapbox)

If you look carefully, you can see differences in the buildings that are at the edge of the perimeter.  These are really taken at different times, although it's hard to get an exact date from these sources.  For specific times and dates, use another service, such as SentinelHub.  Here's that same location, but with a date-stamp of 2022-03-09: 

Pyramids (P/C SentinelHub's EO Browser)


Note that images are usually composed of multiple tiles, each of which might have been taken at a different time.  Here's an example where you can see the tile edges of a location near Kiev.  This is fairly typical as not every satellite pass over a given location will get all of the region in a single shot:  

Satellite photo showing tiling


SearchResearch Lessons 


There are many different mapping products with widely varying capabilities.  It's complicated by the fact that single companies sometimes offer multiple products, using some combination of their own images, their own analytics, and data from multiple other satellites giving multiple kinds of images (different analyses and different sensing bands).  

If you're a researcher, this an exciting time--so much opportunity!  

There are lots of companies creating new products, merging data sets, making new kinds of analytics with speed and frequency.  

I haven't even begun to cover the many aerial image companies that are also combining data to get areas with incredibly high resolution (for instance, NearSpaceLabs are flying balloons to get 10 cm data at reasonable cost.  (Probably not over restricted airspace, though, so don't expect anything from Kiev.)  

Bottom line: For reasonably high-res images WITH fairly recent time stamps, try SentinelHub's PlayGround or EO Browser.  Another solution would be Maxar's DigitalGlobe.  For higher-resolution, you can use other services, but be aware that you might have to spend some money to get those images--or hope that one of the providers image collections happens to also have what you seek.  

And, as always, stay tuned because this space is changing very quickly.  

Search on!  


FOOTNOTE:  This post took a few extra days to write solely because there ARE so many options out there: So many things to check out!  If you're just trying to do a bit of SRS on the cheap, now you know where to go.  But if you're doing this professionally, be sure to look for providers that specialize in your region of interest.  There are companies that do specialty services (e.g. business applications such as counting cars in a shopping mall, or doing agricultural crop health assessments), and there are companies that do speciality regions of the world (e.g., images of the coastline of North America, images over Australia, or imagery of South America). Search BEFORE doing a lot of work on your project!