The Sun's (S) shadow cones ( umbras ) of the Moon (M) and the
Earth (E) are revolving, relatively.. When the Moon's umbra sweeps
the Earth's surface, it is solar eclipse. If the Earth's shadow sweeps
the surface of the Moon, it is lunar eclipse. These do not happen in
every New Moon and Full Moon. They happen, when the
∠
E
M
S
, during New Moon, and the
∠
M
E
S
. during Full
Moon, are very near
180
o
, for near-perfect alignment.
