Astronomy

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Allen Versfeld's picture

Are we really headed for a collision with Andromeda?

The Andromeda Galaxy.  Image credit: NASA/JPL/California Institute of TechnologyDear Urban Astronomer

I recently read that the andromeda system is our closest neighbour. Apparently, our galaxy is on a crash course with the andromeda system. They make it sound like its going to happen in the next few decades. I was just curious how much bigger is andromeda? How close is it to us? And how close are we to impact. Thanks in advance,

Drew

Dear Drew

First thing first, we are indeed on a collision course with the Andromeda Galaxy, but we've got rather more than just a few decades to get our affairs in order, so I wouldn't worry too much just yet.<--break->

Allen Versfeld's picture

Will the Blood Moon harm my unborn baby?

Blood MoonDear Urban Astronomer

I am pregnant, and am worried that all these Blood Moons are harming my baby. I have asked around in my community, but everybody has their own scary story about what will happen to my baby if I go outdoors during the blood moon. Please let me know what precautions I must take.

Yours,

Hypothetical Reader

 

 

Okay so nobody actually mailed this question to me.  But at the time of writing, my wife is pregnant and spends a lot of time online in pregnancy forums and facebook groups and she sees people asking it all the time, which seems odd since neither my wife nor I had ever heard of such fears.  So what's it all about?

Allen Versfeld's picture

Do all planets spin in the same direction?

This very detailed enhanced-colour image from ESO’s Very Large Telescope shows the dramatic effects of very young stars on the dust and gas from which they were born in the star-forming region NGC 6729.  Credit: ESO/Sergey StepanenkoDear Urban Astronomer

Do all planets spin the same way, or are there some planets where the sun rises in their equivalent of West? Does it depend on the particular solar system? What about the stars in a galaxy -- do they all spin in the same direction? Do all galaxies spin the same way, or do they even spin at all?

Regards

Amanda Dominy (extracted from facebook conversation)

Dear Amanda

First, the short answer: All rotations and revolutions in a planetary system are in the same direction, except for when they aren't.  These motions are not necessarily in the same direction between neighbouring stars, even stars born from the same gas cloud.  The stars themselves do move through a galaxy in the same direction in a roughly circular orbit, except for when they don't.

So that's all cleared up then.  But just in case you're still in the dark, here's a more detailed answer:

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