A blood moon is the dramatic nickname for a total lunar eclipse, when Earth’s shadow completely covers the Moon and gives it a coppery red or reddish-brown glow. This phenomenon can only occur during a full moon, when the Sun, Earth, and Moon align perfectly in a straight line.
Unlike ordinary full moons, not every one turns into a blood moon. The reason lies in the Moon’s slightly tilted orbit, which usually prevents Earth’s shadow from covering it. Only when the alignment is precise does Earth block direct sunlight, filtering the light through its atmosphere.
Why does the Moon turn red?
During a total lunar eclipse, sunlight can’t reach the Moon directly. Instead, it passes through Earth’s atmosphere, which scatters shorter wavelengths like blue and green light. The longer red and orange wavelengths bend around Earth and illuminate the Moon’s surface, creating that striking “blood moon” effect.
According to space.com, this is the same natural scattering process that makes sunrises and sunsets appear red. Depending on atmospheric conditions- such as volcanic eruptions, wildfire smoke, dust, or pollution- the Moon can appear anywhere from bright copper to a deep, almost brick-red hue.
When is the next blood moon?
Mark your calendars: the next total lunar eclipse (blood moon) will occur on September 7, 2025. Skywatchers across Asia and Western Australia will have the best view, as the eclipse will be visible in its entirety. Parts of Europe, Africa, eastern Australia, and New Zealand will also catch glimpses of some phases. Unfortunately, this celestial event won’t be visible from the Americas.
How rare are Blood Moons?
According to NASA, Earth experiences two to four lunar eclipses every year, although not all of them are total. On average, any given location on Earth sees a total lunar eclipse about once every two to three years. Each eclipse can be observed from roughly half of Earth’s surface, depending on local night-time conditions.
