The shadow that Aristotle saw was caused by a lunar eclipse. At that time the sun, earth, and the moon nearly straight alignment caused the Earth's shadow to be reflected on the moon. This shadow is what ultimately led Aristotle to believe that the Earth was a sphere. This should not be confused with a solar eclipse which is similar but instead the sun, moon, and earth align in that order which causes the moon to completely block the sun to anyone on earth.
A peplomer is a glycoprotein spike on a viral capsid or viral envelope. These protrusions will only bind to certain receptors on the host cell; they are essential for both host specificity and viral infectivity.
