A constellation of radar satellites in LEO orbit is being used to monitor the open ocean. The system collects two SAR images of the same area separated by a few hours in time. In the first image, the ocean appears dark, but in the second it appears brighter. What is the most likely cause of this difference? A. An oil spill occurred between the images, making the water more smooth. B. The wind speed increased between the images, causing waves to form on the ocean surface. C. The first image was collected at an oblique angle, while the second was taken looking straight down (a nadir view). D. The collection geometry changed between images resulting in a Doppler shift of the signal intensity.
Stellar evolution
We may see thousands of stars in the dark sky. Our universe consists of billions of stars. Stars may appear tiny to us but they are huge balls of gasses. Sun is a star of average size. Some stars are even a thousand times larger than the sun. The stars do not exist forever they have a certain lifetime. The life span of the sun is about 10 billion years. The star undergoes various changes during its lifetime, this process is called stellar evolution. The structure of the sun-like star is shown below.
Red Shift
It is an astronomical phenomenon. In this phenomenon, increase in wavelength with corresponding decrease in photon energy and frequency of radiation of light. It is the displacement of spectrum of any kind of astronomical object to the longer wavelengths (red) side.
A constellation of radar satellites in LEO orbit is being used to monitor the open ocean. The system collects two SAR images of the same area separated by a few hours in time. In the first image, the ocean appears dark, but in the second it appears brighter. What is the most likely cause of this difference?
A. An oil spill occurred between the images, making the water more smooth.
B. The wind speed increased between the images, causing waves to form on the ocean surface.
C. The first image was collected at an oblique angle, while the second was taken looking straight down (a nadir view).
D. The collection geometry changed between images resulting in a Doppler shift of the signal intensity.
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