A lunar eclipse occurs when the Moon passes directly behind Earth and into its shadow. This can occur only when the Sun, Earth, and Moon are exactly or very closely aligned (in syzygy), with Earth between the other two. A lunar eclipse can occur only on the night of a full moon.
The bones in your arm are a structure that first appeared in lobe fin fishes, such as the Eusthenopteron fish. let me know if you have any other questions :)
