Could astronauts find their bearings in the Universe after being transported 6 gigalightyears from Earth?
In my world, humanity reaches their new home among the stars by way of a portal that pops into the solar system one day. This portal instantaneously transports those who enter to a place that is located a jaw-dropping 6 gigalightyears (six billion lightyears) from Earth.
But the astronauts traveling there don't know that. Would it even be possible for them to determine how far they had been transported? And in what direction?
I would imagine that they'd look for known galaxies, or perhaps look at the cosmic microwave background for clues. But those things might appear radically different, considering the astronauts have been transported over a billion years into the past (or is it the future? Wormholes confuse me).
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As long as the astronaut has a map of the sky from Earth where stellar bodies are grouped by distance (like on onion peels), then geometry suggests that there must be at least one point, or more likely a ring in the alien sky that looks rather similar, if not identical to a ring of equal size from the Earth sky. Get the distance of the celestial bodies in the ring and you have the half distance from Earth (3bn light years in this example).
AN algorithm to find rings with certain characteristics in the sky has been used to study and identify echoes in the background radiation if I remember correctly.
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