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rainbow effect

Rainbow plane offsets

July 22, 2016

When we had a look at the ‘rainbow effect’ of planes in flight we mentioned that the offsets of the different images were a result of both the plane’s movement and the movement of the satellite taking the photos. We thought it would be worth having a look at that in more detail.

We know that most imaging satellites follow a sun-synchronous orbit. It is fairly easy to approximate that orbit relative to a plane in flight by drawing a line from the location of the plane to form a tangent on the right hand side of the North pole with the circle of latitude 82° N. For increased accuracy we will try to follow the tail of the plane.

In the image above, the satellite was travelling north to south in the direction of the red line although not necessarily directly overhead.

The satellite captured 4 photos: one high resolution grey scale image which we see at (1), and then after a short delay, blue, red and green images in quick succession which we see overlapping at (3).

If the plane was completely stationary, we would have expected the rainbow images to appear at (2) due to parallax and the motion of the satellite. If the satellite was stationary and the plane moving, then we would expect to see them at (4).

Using Google Earth’s measuring tools the distance from (1) to (2) is about 40 m. The distance from (2) to (3) is about 70 m.

This is enough information such that if we knew which satellite took the image, and how long it pauses between the monochrome and colour images, we could work out the approximate altitude and velocity of the plane. Alternatively, if we knew the altitude and velocity of the plane, we could, work out which satellites could have taken the image.

One useful fact is that all the possible satellites have very similar velocities which we can approximate at 7.5 km/s.

Wikipedia suggests that a typical plane cruises at 878–926 km/h at an altitude of around 12km and that a much higher altitude is not possible.

So, if we start by guessing the planes altitude at 12 km, its velocity at 900 km/h then we get the satellite altitude at about 550 km. Now we look through this list to try and find a matching satellite from DigitalGlobe – keeping in mind the image was captured in 2012 so satellites launched after that date must be excluded. Our best guess is that the image was probably captured by a satellite in a slightly lower orbit such as World-View-1 at an altitude of 496 Km and to make our calculations match up, the plane was probably at a slightly lower altitude of 11 km above sea level. (The ground at this location is 1.3 km above sea level.)

The time between the the monochrome and colour images is about 0.27 seconds.

If any of our readers knows of a reference with satellite orbit data in tabular form for a wide variety of imaging satellites please let us know in the comments.

We also came across this image:

The images of the plane appear to have been sheared and offset slightly in a horizontal direction, but the image of the ground does not seem to have been affected. We don’t know how this happened. Do our readers have any suggestions? One of the images in our earlier post on the ‘rainbow effect’ also includes an plane which seems to have a double tail which may be a related effect.

To find the above planes in Google Earth download this KML file.

We found the above planes using the Google Earth Community aircraft in flight list.

Filed Under: Site News Tagged With: rainbow effect

Google Earth ‘Rainbow Planes’ Inspire Art

January 22, 2016

Fast moving objects, such as aircraft, when seen in satellite imagery often show ghosting or a ‘rainbow effect’. This is caused by the way satellite cameras work taking several photos in succession using different wavelengths of light. The separate images are later combined to produce the full colour images we see in Google Earth. If anything moved between shots then we see an image for each of the three primary colours in slightly different locations and usually a fourth, slightly higher resolution image, in grey-scale. To see examples of this see this post we wrote on the subject.

This effect has inspired artist James Bridle, who has created two different artworks based on the rainbow effect. We came across this article about his second one.

You can read more about it on the artist’s blog here. Also check out his other artwork here as many of them are mapping or satellite imagery related.


Rainbow Plane 002 in Kiev, Ukraine, by James Bridle.


We were able to track it down in Google Earth imagery, but it is only barely visible and the rainbow effect is not visible at all.

We also tracked down most of the locations of another series of his called ‘Drone Shadow’ but only found one in Google Earth imagery and it is also only barely visible. To see the locations in Google Earth download this KML file.

Filed Under: Site News Tagged With: art, James Bridle, rainbow effect

Planes in flight and the rainbow effect

March 11, 2015

Ever since Google Earth was first released, users have been spotting aircraft in flight in the imagery.

When an aircraft is captured in flight in Google Earth it is not uncommon for it to have a second ghostly image next to it, or in some cases a rainbow effect. This is caused by the way satellite cameras are designed. Satellites have multiple cameras for capturing imagery in different wavelengths of light. A common setup is to have a high resolution monochrome camera and then a separate camera that takes photos with various colour filters in quick succession. The multiple images are then combined to form what you see in Google Earth. However, if there is a fast moving object in the scene such as an aircraft, it will have moved between exposures and the ghosting or rainbow effects can be seen, depending on what type of camera the satellite is using. In addition to the aircraft’s movement, the satellite itself is moving and due to parallax the aircraft will appear to have moved in relation to the ground. This often results in the multiple images being offset from the direction the aircraft is travelling in.


The satellite took images in quick succession with blue, green then red colour filters, and finally a higher resolution image in monochrome.


In this image, the satellite took the high resolution monochrome image first, and then red, green and blue colour filters. We don’t know how the double image of the aircraft tail happened.


This image shows an aircraft and its shadow both exhibiting ghosting.

Satellites are also capable of taking images in spectral ranges far outside the visible range such as in the infrared. These images have a variety of uses including mineral exploration, environmental monitoring, agriculture and military. Digital Globe’s World View 3 that was launched last year and whose imagery we recently looked at shows on its datasheet that it is capable of capturing a variety of bands in the infra-red range.

Google Earth Hacks has a couple of collections of aircraft in flight: civilian aircraft and military aircraft. Do our readers know of any more comprehensive collections?

To find the aircraft featured in this post, download this KML file.

Filed Under: Google Earth Tips Tagged With: aircraft in flight, rainbow effect



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