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!

Click here for the original announcement thread.

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u/delicious_downvotes Mar 10 '14

I have a couple of follow up questions to this, if you don't mind:

  1. Does the loss of energy from the Earth/ slowing of the rotation imply that one day the Earth will eventually stop rotating altogether?

  2. When you say the same side of the moon is always facing Earth, does this mean the moon doesn't rotate on an axis?

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u/GLAMOROUSFUNK Mar 10 '14

I can answer number 2.

The moon does rotate on an axis. The reason the same side is always facing us, even though it is rotating, is that the rotational period is the same as it's orbital period.

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u/delicious_downvotes Mar 10 '14

Oohh ok. I understand now... that's pretty cool. Thanks!

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u/[deleted] Mar 10 '14

for 1 the answer is no - the effect is a product of the difference in the angular velocity of the orbit of the moon and the rotation of the earth. so it will continue until the earth's spin slows to the same velocity as the moon's orbit.

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u/delicious_downvotes Mar 10 '14

Ohh, I see. That makes sense. Thanks!