In a lunar eclipse, the Moon often passes through two regions of Earth's shadow: an outer penumbra, where direct sunlight is dimmed, and an inner umbra, where indirect and much dimmer sunlight refracted by Earth's atmosphere shines on the Moon, leaving a reddish color. The Danjon scale illustrates the range of colors and brightness the Moon can take on during a total lunar eclipse. It is also a useful tool to visual observers in characterizing the appearance of an eclipse.
The evaluation of an L value is best done with the naked eye, binoculars, or a small telescope near the time of mid. Why does the Moon turn red, orange, or gold during a total lunar eclipse? It's generally for the same reasons the Sun turns red when it rises or sets. We explore why the lunar surface turns a beautiful reddish color to become a "blood moon" during the totality phase of a total lunar eclipse.
During a total lunar eclipse, the Earth casts a shadow on the Moon while some sunlight, scattered by our atmosphere, still manages to illuminate the lunar surface. There was an opportunity Thursday night to catch the March 2025 "Blood Moon," a phenomenon that colors the full moon in shades of red, orange and yellow during a total lunar eclipse. In a lunar eclipse, the sun, Earth and moon line up, with the Earth in the middle.
Image via NASA. Bottom line: Coming up the total lunar eclipse of September 7, 2025. What is a lunar eclipse and why do they happen? Discover the science of lunar eclipses and view pictures of the rusty-red 'blood Moon'.
During a total lunar eclipse, the Moon can turn a deep red, creating a beautiful, somewhat ethereal sight. This red color comes from sunlight passing through Earth's atmosphere and reaching the Moon. Lunar eclipses are sometimes called "Blood Moons" because of this phenomenon.
How can I observe the eclipse? You don't need any special equipment to observe a lunar eclipse, although binoculars or a telescope will enhance the view and the red color. A dark environment away from bright lights makes for the best viewing conditions.