How Google Earth displays dates on their imagery

As you probably know, when you’re looking at an area on Google Earth, the date the imagery was captured appears in the lower-left corner, as shown here:

imagery-date.jpg

However, what does that date actually mean? As some of you have pointed out, the date doesn’t always correspond with the imagery (snow on the ground in July, etc).

For standard satellite images, it’s simply the date the imagery was taken, which makes sense. Easy enough. The discrepancies arise when Google loads imagery for a large area from a commercial aerial provider. In those cases, they’re given a range of dates for the imagery. The date you see on the screen is the “oldest known date” for that imagery, while the tic mark in the Historical Imagery sliders is the “newest known date”. In many cases, those date ranges can be up to a few months apart.
To confuse it further, some providers don’t even have exact dates for a batch of imagery; they might simply say “April-June, 2010″. In those cases, Google considers that to be “April 1 – June 30, 2010″, and then displays the date as explained in the previous paragraph.

While the system obviously isn’t perfect, it’s certainly improving. Google Earth didn’t start showing the date in the corner until version 5 came out (so you had less of an idea of when the imagery was captured), and the Historical Imagery tool was certainly a great addition to Google Earth.

As the pace and quantity of imagery updates continue to increase, I expect we’ll see some refinements to this system over the coming years to help it become even more accurate and useful.

About Mickey Mellen

Mickey has been using Google Earth since it was released in 2005, and has created a variety of geo-related sites including Google Earth Hacks. He runs a web design firm in Marietta, GA, where he lives with his wife and two kids.



Comments

  1. Many thanks for this very helpful explanation.
    I guess the obvious inconsistencies raised doubts about the dates as a whole, but now we know the date should usually be correct to the year or better.

  2. One of the problems that I find with that date is that they use ‘American’ date format, so a date of 1/7/2010 to the rest of us means 1st Jul, but it is actually 7th Jan, which can be very confusing.

  3. This is good to know. We use the maps to date sites and their history. This will help us to understand what is happening a little better.

  4. Hi. I have a google immage with a date in the lower left corner but I don’t have the coordinates. If I know the country that it was taken in, how can I use the image date to narrow down my search for the location?

  5. In my country and the other countries around , the date is written is this format ( day-month-year).
    My country is Egypt.

  6. Santiago Casal says:

    I used to be able to see a photo dated October 30, 2011 that was taken of the Chavez Memorial Solar Calendar site in Berkeley, California. Now when I access Google Earth what I get is a photo that carries the date Oct 12, 2011. We made many changes between Oct 12 and 30th that are not reflected in the Oct. 12 photo. HOW CAN I ACCESS THE OCT 30, 2011 PHOTO?

  7. Martin H Goodall says:

    Some images displaying dates between, for example, 2005 and 2008 appear from other evidence to be up to TWO YEARS earlier than the stated imagery date.
    Similarly, I am aware of a Street View that appears to be about ONE YEAR earlier than the stated imagery date.
    Can Google explain these apparent discrepancies? This is urgent as we are curently involved in a dispute in which the other party is relying on the Google imagery dates, whereas we are convinmced that they show the position on the ground at least a year, and possbly two years, earlier.

  8. I am running GE 7 and the imagery date for my view is 6/30/11…but my client sent me a screen shot of the same area with a newer date on the imagery? How is this possible

  9. Bill Wagner says:

    Westphalia, Indiana is a small farming community which used to have a Railroad run through it. The satellite pictures clearly show the railroad has been removed. Tracks are gone and in many places construction built and clearly vegetation over the old railroad bed. I believe that was more than five years ago. The ground view of the town shows the railroad there and crossing signals apparently functioning. How can I tell when the ground pictures were taken, and if very old, what is the policy on updating the information. This is a rural area but the ground pictures are on a state road at a junction with another state road.

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