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105

Deep space radio signal reaches Earth after 8 billion years (www.earth.com)

submitted 3 weeks ago by [email protected] to c/[email protected]

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[–] [email protected] 17 points 3 weeks ago (3 children)

How do they date a radio transmission?

[–] [email protected] 11 points 3 weeks ago

It's tricky, since it's moving at the speed of light, but I still find an icebreaker followed up by an invitation to a low-stakes social engagement to be the best way to proceed /s

[–] [email protected] 17 points 3 weeks ago (1 children)

Triangulation. It arrives at different locations at different times. Enough points gives you direction and distance.

[–] [email protected] 3 points 3 weeks ago (1 children)

You can't use triangulation for anything over a few light-years, the angles are just too acute. And even then, you need to use the full width of Earth's orbit (i.e. repeat a measurement at different times of the year).

I think they just know what the frequency distribution normally is for a burst like this when it is emitted, and use the redshift of the measured frequencies to estimate the distance. Plus they correlate it with the apparent source based on direction (a certain galaxy, in this case, which helped confirm the distance estimate).

[–] [email protected] 1 points 3 weeks ago

The triangulation would mostly be for direction in this case, yeah. Unless we happened to have a radio telescope pointed at the right region of the sky at the time.

[–] [email protected] 23 points 3 weeks ago (1 children)

Reply and say "when did you send this"

[–] [email protected] 7 points 3 weeks ago

New satellite who dis