<story><title>Gravitational attraction of stars and cows</title><url>https://www.johndcook.com/blog/2018/03/28/cow-astrology/</url></story><parent_chain></parent_chain><comment><author>nerfhammer</author><text>Next question, what is the smallest object whose gravitational field could reliably be measured by the accelerometer in your phone? We know that it can measure the field of the Earth at more or less sea level, how much less heavy&amp;#x2F;further away could something get for your phone to feel it?&lt;p&gt;my attempt:&lt;p&gt;&lt;pre&gt;&lt;code&gt;  diameter of earth = 12742 km
  sea level = distance from earth = 12742&amp;#x2F;2
  weight of empire state building = 331000000 kg
  resolution of BMA280 in the iPhone 6: 1&amp;#x2F;4096 g
  mass of earth = 5.972e+24 kg
  gravity of earth = 1 g
  km to m = 1000x

  (12742&amp;#x2F;2. * sqrt(331000000 &amp;#x2F; (5.972e+24 &amp;#x2F; 4096.))) * 1000

  = 3 meters
&lt;/code&gt;&lt;/pre&gt;
So your phone should be able to register 1 bit of resolution when the empire state building is 3 meters away or less, otherwise it would be too far away to detect. Of course the empire state building would need to be compressed into a single point but that&amp;#x27;s a minor practical concern.</text></comment>
<story><title>Gravitational attraction of stars and cows</title><url>https://www.johndcook.com/blog/2018/03/28/cow-astrology/</url></story><parent_chain></parent_chain><comment><author>CobrastanJorji</author><text>I wondered whether &amp;quot;17 miles&amp;quot; is a good estimate for how far I am from a cow, and now I&amp;#x27;m trying to do a sort of Fermi problem in my head and realizing I&amp;#x27;m out of practice for bad job interviews.</text></comment>