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Moon full of mysteries Astronomers shed some light on various lunar facts, myths
BY ELYSIA NEST Gazette Reporter

    Even after nearly fi ve decades of staring into the night sky, Steven Russo still considers the moon compelling and captivating.
    “What’s amazing is it’s the closest object to us and more studies have been done on the moon than any other object in the sky, with all of its phases and eclipses, yet it still remains one of the most complicated objects in our solar system,” said the Malta resident, who has managed the Suits-Bueche Planetarium at the Schenectady Museum Planetarium for almost five years.
    “It’s very misunderstood.”
    Here, Russo, along with a handful of other astronomers, attempt to answer questions about the moon’s behavior and appearance that have mystified people since ancient times.
BLUE MOON
    Everyone has heard the phrase “Once in a blue moon,” which nonastronomically speaking has come to mean a rare event.
    But when it comes to an actual blue moon, Marc Rouleau, director of The University of Texas at Arlington Planetarium, explained that because the moon’s cycle is slightly shorter than most calendar months — averaging 29.5 days — every once in a great while the Earth experiences two full moons in the same month. The second one is dubbed the “blue moon.’’
    Russo said the term dates from something penned in The Farmer’s Almanac during the mid 1930s.
    “Someone just wrote it, and the name stuck and then it disappeared and came back into use in the 1950s. Generally speaking, the media and astronomers call a second full moon in a month a blue moon, but scientifically that is not the case at all.”
    There is a literal blue moon that can sometimes be seen in the winter when sunlight and moonlight are dispersed in the upper atmosphere, illuminating the blue end of the spectrum as light is reflected from the moon.
    The moon can also take on a blue cast during a lunar eclipse, as Earth’s shadow falls upon the moon.
    According to folklore, during a blue moon, fish bite better, fertility is heightened and it’s a good time for gardening — but only for aboveground crops.
THE MOON ILLUSION
    The so-called “moon illusion” has befuddled society since early historical times.
    There is no doubt about it. The moon seems larger when it is near the horizon than when it is high in the sky. Some people judge it to be as much as twice as big.
    The same illusion is observed with any extended object in the sky, such as a constellation.
    Christian Aars, an assistant physics professor at Angelo State University in Texas, said this illusion occurs because the brain usually assumes you are upright when your eyes are open.
    “That leads it to assume that when your head is perpendicular to your neck, you are looking at something relatively nearby, totally earthbound scenery, and when it is parallel to your neck you are looking up into the sky,” he said.
    “If the object is earthbound, it is very important for your survival — as far as your brain is concerned — for you to figure out how far away it is and how big it is. Big things could be potential threats to your survival, and if it’s very close to you it’s also probably worth keeping track of, big or small, just in case it becomes a threat of some sort.” Your brain tells near from far, Aars explained, using what’s called parallax. “Your brain compares where objects are in the field of view of each of your eyes. If there’s a large shift in where the objects appear to be in the field of view of your right eye, compared to the left, your brain assumes the object is very close to you. The smaller that shift appears to be, the further away you think the object is.”
    The moon, Aars said, is actually very far away, and shows almost no apparent shift when your brain does the comparison. So your brain assumes it must be very far away. But if you are looking at it while your head is perpendicular to your neck, it must be “earthbound” — and any earthbound object that is that far away and yet still looks that big to you must be extremely large. So your brain feeds you a “feeling” that what you are looking at must be extra big.
    The net result?
    When the moon is on the horizon, your brain perceives it as being really big. When it’s high in the sky, your brain just shows you literally what you are seeing without any feeling of size. And since the moon really is pretty small in the sky, that’s exactly what you see. It looks small, Aars said.
    To counteract this unusual effect, Russo suggests the following exercise.
    “Bend over and stick your head between your legs while looking at the moon on the horizon. While dangling upside down, you’ll see it suddenly looks the same as it would if you were looking at it overhead,” he said.
HARVEST MOON
    The harvest moon is the closest full moon to the autumnal equinox, typically around Sept. 23 of each year. “Sometimes, it occurs in October,” Rouleau said. “It is known as this because the full moon is up in the sky slightly longer and is often very bright.”
    Historically, this type of moon allowed farmers to harvest their fields late into the night, said John Chumack, with The Chumack Observatories at the University of Dayton Research Institute in Ohio.
THE TIDE
    Thousands of years ago, civilizations became aware the tides of the ocean and the positions of the moon were related, but it wasn’t until Isaac Newton published his theory of gravitation in 1687 that the connection was explained.
    The moon’s gravitational pull is greatest on water on the part of Earth facing the moon, and this makes the water bulge toward the moon, causing a high tide.
    Because Earth and the moon rotate around the sun, Russo said, there is an added modifying factor.
    When the sun and moon are aligned, there are exceptionally strong gravitational forces, causing very high and very low tides, called spring tides, though they have nothing to do with the season. When the sun and moon are not aligned, the gravitational forces cancel each other out, and the tides are not as dramatically high and low. Those are called neap tides.
    Tides vary from day to day. As Earth, moon and sun orbit, their positions constantly shift, causing slightly different gravitational effects. This causes the tides to occur at slightly different times.
MAN IN THE MOON
    Some ancient people look up and see a rabbit. Others see a toad. But most moon-watchers agree that during certain phases, the moon’s surface resembles a man’s face. That resemblance has spawned myths in many cultures, all based on the man who lives on the moon.
    The dark markings on the moon actually come from large basins on the surface that were created when other space objects — meteors and asteroids — crashed into the moon billions of years ago. The “eyes” of the face even have names; the right eye is the Imbrue basin, and the left eye is the Serenitatis basin. The rest of the features aren’t quite as clearly “drawn,” such as a nose and mouth, but most people would agree that the moon appears to be watching us.
FAR SIDE OF THE MOON
    People often refer to the “dark side” of the moon, but there is no such thing. The sun shines on all sides. However, there is a “far side” of the moon that is never seen from Earth. Over the eons, the gravitational forces of Earth have slowed down the moon’s rotation about its axis until the rotational period exactly matches the revolution period about Earth. Therefore, we are always faced with the same side.
JUST A PHASE
    As the moon circles Earth, the shape of the moon seems to change; this is because different amounts of the illuminated part of the moon are facing us. The shape varies from a full moon — when Earth is between the sun and the moon — to a new moon when the moon is between the sun and Earth.
    The moon has four major phases in a month: new moon, first quarter, full moon, last quarter. Those phases are further broken down into waxing crescent, waxing gibbous, waning crescent and waning gibbous, based on how much of the lighted surface is visible.
    FULL MOON
    Astronomically speaking, a full moon occurs for about one minute, when the moon and the sun are on opposite sides of Earth. The reason this instant is so short is that all three bodies are in constant motion.
    However, astronomers consider the full moon to occur over a full day and even more loosely, over three days,
    The night before a full moon and night after full moon look the same to the untrained eye, Russo said.
LUNACY
    The word lunatic comes from luna, Latin for moon.
    It has long been believed that a full moon triggers more suicides than usual, contributes to an increase in crime and even sends women into labor.
    In fiction and film, the werewolf needed the light of the full moon to come to life.
    Modern-day scientists contend the myth that the moon creates strange events arises from ancient times when there were few cities and the countryside was extremely dark on moonless nights.
    The full moon provided enough light for people to attend festivals and other gatherings at night, and this was when they were most susceptible to thieves, pickpockets and robbers.
    Russo said numerous studies have been done to see if there are any such correlations between full moons and crime or other “crazy” behavior, and there has yet to be any connection established.
RING AROUND MOON
    This phenomenon, according to Russo, is usually because of high-altitude, thin cirrus clouds. Those clouds contain water vapor that sometimes freezes into ice crystals, causing the moonlight to diffract through the crystals creating a halo around the moon.
    “A little halo usually means nothing,” he said. “But if there is a wide halo, 99 percent of the time we will have some kind of precipitation within the next 36 hours,” he said.