ISRO's next mission to the Sun is Aditya-L1, (also here), which will be placed at the Sun-Earth Lagrangian point L-1.

Why it is not placed near L-4 or L-5, since these are stable equilibrium point whereas L-1 is unstable equilibrium? What is the advantage to placing Sun-observing satellites like Aditya near the L-1 point?

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    $\begingroup$ You might look at the distances involved. L4 and L5 are 1AU away from the Earth, whereas L1 is 100 times closer. Then think about trying to use your cell phone or WiFi to upload data, and having a choice between two seats, one being 100 times farther from the transmitter than the other. $\endgroup$
    – uhoh
    Jan 29, 2018 at 18:29
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    $\begingroup$ fyi there is also a Space Exploration Stack Exchange site. You can search there for questions about halo orbits. $\endgroup$
    – uhoh
    Jan 29, 2018 at 18:30
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    $\begingroup$ I find the Wiki list of objects at Lagrange points interesting. $\endgroup$
    – B--rian
    Jun 29, 2021 at 10:11


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