Since everything is moving relative to each other (The Earth rotates around it's only varying axis, around the Sun and in the galaxy etc) it is hard to define a pure inertial system - or coordinate system for positioning if you like. Hence we call upon Einstein! :-)
PlanetBye is a blog run by Bente Lilja Bye aka Stellare. PlanetBye covers mainly scientific topics but also completely random topics like art, social media, personal ramblings etc. The posts on this blog are generally short with links to further reading and sources of information. Clicking on images is encouraged.