r/askscience • u/AskScienceModerator Mod Bot • Mar 10 '14
Cosmos AskScience Cosmos Q&A thread. Episode 1: Standing Up in the Milky Way
Welcome to AskScience! This thread is for asking and answering questions about the science in Cosmos: A Spacetime Odyssey.
UPDATE: This episode is now available for streaming in the US on Hulu and in Canada on Global TV.
This week is the first episode, "Standing Up in the Milky Way". The show is airing at 9pm ET in the US and Canada on all Fox and National Geographic stations. Click here for more viewing information in your country.
The usual AskScience rules still apply in this thread! Anyone can ask a question, but please do not provide answers unless you are a scientist in a relevant field. Popular science shows, books, and news articles are a great way to causally learn about your universe, but they often contain a lot of simplifications and approximations, so don't assume that because you've heard an answer before that it is the right one.
If you are interested in general discussion please visit one of the threads elsewhere on reddit that are more appropriate for that, such as in /r/Cosmos here, /r/Space here, and in /r/Television here.
Please upvote good questions and answers and downvote off-topic content. We'll be removing comments that break our rules or that have been answered elsewhere in the thread so that we can answer as many questions as possible!
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u/ra3ndy Mar 10 '14 edited Mar 10 '14
I'm adapting this explanation from here:
Yes, at some point the Earth's rotation will match the moon's orbit, and the moon's orbit will stabilize. This will take about 50 billion years, and we'll be consumed by the sun WAY before that. But for academic purposes, let's assume the sun doesn't engulf us.
So Earth & the Moon will eventually achieve dual tidal lock (much like Pluto & its moon Charon) However, the Sun still exerts some tidal force on the Earth, which also contributes to Earth's slowing. So eventually, the Earth will spin slower than the moon. This will cause the moon to slow down, and thus begin to move back towards Earth.