Moon Barcelona, Catalonia, Spain

Lunar phases are the visible changes in the illuminated part of the Moon. They are only visual, because the Moon doesn't actually change. It's the way we see it from Earth that changes. The Moon's illumination shifts as it orbits the Earth, with the Sun lighting up different sides of the satellite over time. Because of this, the way we see the Moon constantly changes.

Lunar phases are related to the Moon's position in Earth's orbit. The mutual location of the Moon, the Earth, and the Sun is constantly changing. The sunlight illuminates different parts of the Moon, and the lunar terminator — the boundary between the lit and the dark areas — shifts. This is what makes the shape of the Moon appear different.

14.8 days after the new moon, the Moon is directly opposite the Sun. This is called a full moon. The Sun illuminates the Moon completely, and we can see the fully illuminated lunar disk from the Earth. It’s the opposite of the new moon and is the brightest phase in the lunar cycle.

Today in Barcelona, the Moon is in its Waning Gibbous phase. The Moon is 80.4% illuminated. Today the Moon will rise at 8:54 pm. The Moon will set at 12:14 pm.