THE USM SOUTHWORTH PLANETARIUM 207-780-4249 www.usm.maine.edu/planet 70 Falmouth Street Portland, Maine 04103 43.6667° N 70.2667° W Altitude: 10 feet below sea level Founded January 1970 Julian date: 2458652.5 "We love the Universe . It's great!" THE DAILY ASTRONOMER Tuesday, June 18, 2019 More Moon Demytification Ask most scientists and they'll tell you, either lamentably or cheerfully, that no matter how long they labor or how ardently they strive, they'll never solve all the mysteries. Quite often, in fact, the answer to one question will prompt others: like the fearsome Hydra sprouting two heads out of each bloodied stump, just to wax poetic. Well, yesterday's moon demystification article has lead to other moon based questions and myths that we want to promptly address before moving on to other topics. *THE MOON REFLECTS MOST OF THE SUNLIGHT IT RECEIVES?* Status: MYTH The moon reflects about six percent of all incidental sunlight on average. Astronomers measure the ratio of a body's reflected to incidental sunlight with a value called "albedo." A body with an albedo of 0 absorbs all incoming light. A body with an albedo of 1 reflects all incoming light. The moon's albedo is 0.07. This number is an average as the darker parts of the moon such as the "maria," absorb more light that surrounding regions. *THE MOON IS THE LARGEST MOON IN THE SOLAR SYSTEM?* Status: MYTH...with qualifications In absolute terms, the moon ranks fifth in size of all the moons in the solar system. The moon's diameter is 3,475 kilometers. Jupiter's largest moon, Ganymede, with a diameter of 5,262 kilometers, is the solar system's biggest moon. However, in terms of size relative to orbiting body, the moon ranks second. Pluto's moon Charon is the largest moon in the solar system when measured relative to its parent body. A it is about 1/9th as massive as Pluto, Charon actually doesn't revolve around Pluto. Instead, Pluto and Charon revolve around a common barycenter. However, if one subscribes to the preposterous notion that Pluto isn't a planet, then, yes, when measured in relation to its parent body, Earth's moon is the solar system's largest. *PIECES OF THE MOON ARE SCATTERED ON EARTH?* Status: FACT Scientists know that Earth's surface contains innumerable pieces of the moon, more formally known as "lunar meteorites." When an asteroid strikes the moon, fragments of the moon will be propelled about the lunar terrain. As the moon's gravity is about one-sixth that of Earth, many of these pieces achieve escape velocity and fly away from the moon. Naturally, many of these dislodged pieces will crash onto the nearest large body to the moon, our planet Earth. Researchers are able to identify lunar meteorites by chemical analysis: they will match the composition of moon rocks that astronauts brought back to Earth on purpose. [image: image020.jpg] A* lunar meteorite *found in Antarctica in January 1989. *ALL THE MOON WALKERS HAVE DIED?* Status: MYTH Twelve astronauts walked on the moon's surface. Neil Armstrong, the first astronaut to set foot on the moon and Eugene Cernan, the last astronaut to walk on the moon, have both died. However, four other moon walkers still remain: Buzz Aldrin (Apollo 11) David Scott (Apollo 15) Charlie Duke (Apollo 16) and Harrison Schmidt (Apollo 17) *THE AMERICAN FLAG HAS BEEN BLEACHED WHITE?* Status: Almost certainly true The American flag was vibrantly colored with the red, white and blue when it was planted in the lunar soil. However, after the passage of so many years under the scorching Sun, the flag has most likely been bleached white. We know, ourselves, that clothes can and do fade here on Earth if they worn outside excessively. However, on the moon, the Sun is much harsher owing to the the lack of any protective atmosphere. Colors fade rapidly. *THE FOOTPRINTS LEFT BY THE ASTRONAUTS ARE STILL ON THE MOON'S SURFACE?* Status: FACT If we teleported to the moon right now, we'd see the astronauts' footprints pressed onto the lunar soil looking so fresh one would have thought the astronauts had just left them. The moon lacks Earth's erosion mechanisms of wind and water, so craters and other imprints will remain on the moon for quite a long time. In fact, the astronauts' footprint will only be wicked away by the tediously slow process of micrometeorite impacts. We estimate that the footprints, if left alone, will remain on the moon for at least the next 500,000 years!