Not exactly the same, but https://en.wikipedia.org/wiki/Very-long-baseline_interferome... is a technique used in radio astronomy which uses two receivers a long way apart and a very accurate clock to approximate having a radio telescope the size of the distance between them. By putting one receiver on a satellite, measurements have been made with a separation of 300,000km.
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fictional question: how much detail would we see if we could somehow make a telescope with a 1 million km diameter
Not exactly the same, but https://en.wikipedia.org/wiki/Very-long-baseline_interferome... is a technique used in radio astronomy which uses two receivers a long way apart and a very accurate clock to approximate having a radio telescope the size of the distance between them. By putting one receiver on a satellite, measurements have been made with a separation of 300,000km.