Have you ever wondered why do you see a red Moon during a total lunar eclipse?
Well, here is the answer:
"Lunar eclipses occur when the Moon passes through the Earth’s shadow, however, for a total lunar eclipse to occur, the Moon and Earth have to be on the same orbital plane with the Sun — this is known as a syzygy.
During a total lunar eclipse, the Moon travels completely into the Earth’s shadow (umbra). Even though the Moon is immersed in the Earth’s shadow, indirect sunlight will still reach the Moon.
As sunlight passes through Earth’s atmosphere it gets absorbed and then radiated out (scattered). The atmosphere filters out most of the blue-colored light. What’s left over is the orange- and red-colored light. From the Moon’s perspective the Earth’s edge appears to glow bright orange or red. This red-colored light passes through our atmosphere without getting scattered, projecting indirect, reddish light onto the Moon."
"Not all total lunar eclipses are the same when it comes to color. Totality can appear anywhere from a dark brick color to a bright coppery red. This color can be quantified and described on what is known as the Danjon Scale, with 0 being a very dark eclipse with the Moon barely visible, to a 4, meaning a very bright eclipse."
Two lunar eclipses in 2003; their ratings on the Danjon Scale would be roughly 2 (left) and 4 (right). Via wikipedia.org.