.. post:: 2021-05-04
   :tags: AE4874 I, astronomy, random
   :author: Geoffrey

An Impermanent Perspective
==========================

Saw this video in class today, it really inspired me!

.. raw:: html

    <div>
        <div style="position:relative;padding-top:56.25%;">
            <iframe src="https://www.youtube.com/embed/3f_21N3wcX8" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen
             style="position:absolute;top:0;left:0;width:100%;height:100%;">
            </iframe>
        </div>
    </div>


I found an extract that summarises the phenomena nicely:

    In lunar astronomy, libration is the wagging or wavering of the Moon perceived
    by Earth-bound observers and caused by changes in their perspective. It permits
    an observer to see slightly different hemispheres of the surface at different
    times. It is similar in both cause and effect to the changes in the Moon's
    apparent size due to changes in distance. It is caused by three mechanisms
    detailed below, two of which cause a relatively tiny physical libration via
    tidal forces exerted by the Earth. Such true librations are known as well for
    other moons with locked rotation. [`source`_]

.. _`source`: https://en.wikipedia.org/wiki/Libration