Each of the subjects below is expanded upon in the pages linked to.

Distances and Sizes

Humans have great trouble to imagine the enormous distances even in our own close neighbourhood of the Galaxy, let alone the universe.

About Eclipses of the Sun and Moon

Eclipses occur when the Moon gets between the Sun and the Earth (solar eclipse) or when the Earth gets between the Sun and the Moon (lunar eclipse).


Ancient Greeks realised that it is possible to make overlapping star charts using only circles and invented the astrolabe, a device that is simpler than you may think.