Launch our Interactive Phases of the Moon Tool!
Will moonlight interfere with nighttime observing when you plan to take vacation next summer? What was the Moon's exact phase on the day you were born? When's the next opportunity to photograph a young crescent Moon?
Sky & Telescope's interactive tool will show the Moon's phase for any date from 4000 BC to AD 8000.
How to Use the Phases of the Moon Tool
The tool will open with the current phase of the Moon, including a text description at the bottom.
To obtain the Moon's phase on any other date, select the month and day from the dropdown menus and type the year. Select AD or BC, then click Calculate.
Want to experiment? Try these examples, all of which were described in more detail in past articles from Sky & Telescope:
- Bobbing in a lifeboat in the predawn hours of April 15, 1912, Titanic survivor Lawrence Beesley described "the thinnest, palest of moons" rising over the ocean to the east. The previous evening, the Moon's absence from the sky had made it hard for lookouts to spot the iceberg that sank the ship. (S&T: October 1993, page 79)
- During World War II, Allied prisoners held at Stalag Luft III picked the "dark of the Moon" — March 24, 1944 — for their daring breakout to minimize the chance of being spotted by German guards. Their exploits are the subject of the classic 1963 movie The Great Escape. (S&T: April 1994, page 86)
- Thales of ancient Greece earned his reputation by successfully predicting the total solar eclipse of May 28, 585 BC. Our Moon Box does not show eclipses, but it does indicate that the Moon was exactly new on that date. (S&T: May 1994, page 36)
- At the start of the American Revolution, Paul Revere made his famous "midnight ride" on April 18, 1775, with bright moonlight to guide the way — a fact mentioned five times in the stirring poem of Henry Wadsworth Longfellow that begins, "Listen, my children, and you shall hear . . ." (S&T: April 1992, page 437)
- Discover which month will be the next to host a Blue Moon.
Note that our Phases of the Moon tool uses the Gregorian calendar after 1582 and the Julian calendar before that year.