About imagery and collection dates in Google Earth
Check out this guide to understand the different types of imagery available in Google Earth and find out how to read the information about image collection dates.
- Satellite and aerial imagery
- Finding imagery dates
- Imagery collected on one date
- Imagery with a range of dates
- 3D Imagery
- Historical imagery
- Street View imagery
- Getting more precise imagery dates
Google Earth compiles and displays a very large collection of imagery, including satellite, aerial, 3D, and Street View imagery.
How imagery is collected
The imagery in Google Earth is collected over time, from various providers and platforms. The imagery isn’t in “real time,” so Google Earth doesn’t show live changes. For instance, this image of central Cairo was collected by the satellite imagery company DigitalGlobe on September 17, 2015:
When and where image date info shows up
For some imagery, Google Earth provides the date when an image was collected. These dates are displayed both:
- at the bottom of the 3D viewer (map window) and
- in the Historical Imagery time slider
While we try to provide accurate information about when an image was collected, we can’t guarantee accuracy or completeness. There are numerous factors which impact how the dates are determined and how precise that information can be.
The satellite and aerial imagery in Google Earth is taken by cameras on satellites and aircraft, which collect each image at a specific date and time. Often those images are brought into Google Earth as a single image with the specific collection date, but sometimes:
- The images are combined into a mosaic of images taken over multiple days or months (displayed as one seamless image in Google Earth) or
- The collection date information is lost or inaccurate due to human error or other issues
All of this impacts the accuracy of the date information displayed in Google Earth.
For many of the images, Google Earth provides an “Imagery Date” listed in the status bar at the bottom of the 3D Viewer:
The date shown is for the image under your cursor’s position on the map and may change as you navigate around:
- If you zoom in close to the ground, then the map you see will likely be made up of one image, versus a mosaic of several images, as mentioned earlier. The date displayed in these cases should stay the same wherever you move your cursor.
- When you zoom out far enough, the seamless image you see will actually be a mosaic of several images; therefore, the date may change as you move your cursor around the map.
- Sometimes no date will be shown, either when there is no date information available for the image or when your cursor is near the seam between two images.
There are also dates, normally just the year, shown in the data provider copyright strings at the bottom of the 3D window, such as "Image © 2015 DigitalGlobe" or "© 2015 Google". These are updated to reflect the current year, and should not be interpreted as the date the imagery was collected:
If you’re using the Historical Imagery tool, then the date on the time slider indicates the newest image on the map. In other words, all images shown on the map will have been collected on the time slider’s displayed date or earlier. See more on Historical Imagery below.
When an imagery provider supplies Google with one date as the acquisition date for an image, we will include that information in Google Earth. In this case, the imagery date shown will reflect that date, and the Historical Imagery slider will show that image on the indicated date.
Many of the images in Google Earth are actually a mosaic of multiple satellite or aerial photos taken over several days or months. Such images do not have a single image date, but rather a range with a start date (earliest/oldest) and an end date (latest/newest) between which the images were collected.
There are also images in Google Earth for which little or no date information was supplied by the data provider. Examples include mosaics with a date like “Summer 1995” or very old aerial imagery, where all we know is the month or year (e.g. “1943”). For images like these, we determine a start and end date within which we can be reasonably certain the image was taken, given everything we know about that image. For example:
- “Summer 1995” might become start:1995-06-01 and end:1995-09-30
- “1943” might become start:1943-01-01 and end:1943-12-31
For all images with date ranges, the “Imagery Date” indicator will show the start date of the range. This is the oldest date in the possible range, so that Google Earth’s will never show a date that’s newer than the actual image collection date.
Historical imagery collected across a range of dates
On the other hand, the Historical Imagery time slider will use the end date (the newest date in the possible range) to determine whether the image is shown on the map. This is so that we’re certain all historical images shown were captured on or before the date on the slider. For these images, you can better understand the bounds of the possible range by comparing the Imagery Date shown with the date when the image appears/disappears using the Historical Imagery tool.
For example, in the screenshot below, you can see an aerial imagery mosaic of wartime Paris which we only know was collected in “1943”. The Imagery Date shows 1/1/1943 (the earliest possible date), while the time slider shows 12/31/1943 (the latest possible date):
For many metropolitan areas Google Earth has 3D imagery available when the “3D Buildings” layer is turned on. This shows detailed terrain and buildings, derived from aerial images collected over multiple dates. For this kind of 3D imagery, Google Earth does not display a collection date, as in this image of San Francisco:
The Historical Imagery tool in Google Earth is a powerful way to explore imagery of a place through time. In places where there are multiple images available, you can view historical satellite and aerial imagery.
You can access this imagery by clicking the clock icon in the Google Earth menu or by selecting “Historical Imagery” from the View menu:
How the time slider displays image dates
When you turn on Historical Imagery, a time slider appears in the upper left of the map window. This slider allows you to browse through time:
When viewing Historical Imagery, the date indicated on the time slider indicates the newest image on the map, which means that the images shown were captured on or before that date. The time slider also shows where in time there are images available in the current map view, indicated by the white tick marks on the slider.
Note that the Historical Imagery tool currently displays images in one-day steps, so if the database contains two overlapping images of a place collected the same day, only one of them will be viewable in Google Earth.
Example of Historical Imagery for Crissy Field Park, San Francisco, California
Here is the current imagery displayed in Google Earth of Crissy Field park in San Francisco, California, collected April 1, 2015:
Using the Historical Imagery tool, you can view images of Crissy Field all the way back to July 31, 1938, when Crissy Field was the site of a military base:
Sometimes the dates shown on the time slider and in the status bar are offset by one day due to timezone differences between the image collection date/time and the timezone of the computer.
By default, Google Earth uses the host computer’s time zone, but this can be changed to UTC or any other time zone through the settings menu (wrench icon) in the time slider.
In Google Earth, you can also explore Street View imagery. When viewing a Street View panorama, you can see the month and year a panorama was collected at the bottom of the screen.
For example, this image, featuring the Ferry Building in San Francisco, California, was collected in October 2015:
If you want to see older Street View images of the same place, go to a location in Google Maps, and, where available, you can view historical Street View images. Learn more in the Google Maps Help Center.
If you are looking for more precise or detailed information about the date or time at which an image in Google Earth was collected, you will need to contact the original provider of that dataset. For example, for satellite imagery from DigitalGlobe, you can search the DigitalGlobe catalog to confirm the date on which their system says an image was collected.
Google is not able to provide any more information about imagery it owns beyond what is displayed in Google Earth and Maps.