# Land in Focus – Basics of Remote Sensing

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# Discussion

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• # Temporal Resolution

Posted by on September 30, 2021 at 3:18 pm
4 Members · 8 Replies
• 8 Replies
• ### Helena van Mierlo

Member
June 29, 2023 at 8:18 pm

Regardless of my other feedback: I absolutely love this course. It’s the best course I have ever seen in the remote sensing domain.

• ### Helena van Mierlo

Member
June 29, 2023 at 8:17 pm

Quiz questions 1 and 2 are incorrect:

1: SPOT has a temporal resolution of 1 day (SPOT 6 and 7 together) while Landsat has much lower temporal resolution (16 days divided by 2)

2: See my other remarks about satellites going slower as they move further from Earth.

• ### Helena van Mierlo

Member
June 29, 2023 at 7:55 pm

You might want to change the sentence:

‘With higher flight altitudes, satellites can travel more quickly around the Earth. While this is related to less spatial resolution, the temporal resolution is increased.’ with:

‘With higher flight altitudes, satellites will travel slower and at a specific altitude it will be as slow as the actual rotational velocity as the Earth itself (geostationary satellite), resulting in a static positioning of the satellite above a specific area on Earth. As the satellite does not move away from the area, multiple observations can be made of the same area within a very short time. The drawback of such satellite orbits is that they only cover a limited area of the Earth.’

• ### Helena van Mierlo

Member
June 29, 2023 at 8:12 pm

Additional explanation: the further away a satellite is from Earth, the slower its velocity, and therefore the longer it takes to make a full orbit around the Earth to come back to the same point above Earth, and therefore the lower its temporal resolution. However, if you go even further away, at some point, the velocity wrt the area below, becomes zero, so the satellite never makes a full orbit around Earth, it just stands still wrt to the area below. At that point, it actually can have a high temporal resolution, because it can take images as often as it wants, of the same area.

• ### Helena van Mierlo

Member
June 29, 2023 at 7:48 pm

You might want to change the sentence: ‘With higher flight altitudes, satellites can travel more quickly around the Earth.’ with: ‘With higher flight altitudes, satellites can travel slower and approach the same rotational velocity as the Earth itself, making the satellite appear static above a specific location on Earth’

• ### Azeem Khalid

Member
October 7, 2023 at 7:03 pm

endorsed

• ### Helena van Mierlo

Member
June 29, 2023 at 8:06 pm