If you use Earth, you can use atmospheric lensing (rather than gravitational) to get a focal point inside the Earth–Moon system: https://www.scientificamerican.

If you use Earth, you can use atmospheric lensing (rather than gravitational) to get a focal point inside the Earth–Moon system: https://www.scientificamerican.com/article/earth-could-be-a-lens-for-a-revolutionary-space-telescope/ https://www.scientificamerican.com/article/earth-could-be-a-...