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by willis936 1612 days ago
Earth's umbra doesn't reach L2.

https://en.wikipedia.org/wiki/Umbra,_penumbra_and_antumbra

https://astronomy.stackexchange.com/questions/13585/does-ear...

2 comments

I did some research here to understand this better: https://webb.nasa.gov/content/about/orbit.html

> This [L2] orbit (which takes Webb about 6 months to complete once) keeps the telescope out of the shadows of both the Earth and Moon.

>What is special about this orbit is that it lets the telescope stay in line with the Earth as it moves around the Sun.

and

> Webb's position out at L2 also makes it easy for us to talk to it. Since it will always be at the same location relative to Earth-in the midnight sky about 1.5 million km away - we can have continuous communications with it as the Earth rotates through the Deep Space Network (DSN)

Ah, that stack exchange comment is super interesting.

"If Earth would be 9% larger in diameter, but with the same mass, its umbra would end almost exactly at L2."