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Earth Time, Moon Phases and Eclipses All graphics, photos and text copyright 2007 Kris H. Light http://easttennesseewildflowers.com/ Revolution: 1 Year = 365.4 days It takes the Earth 365.4 days, or one year, to revolve around the Sun. Every 4 years a leap year adds an extra day. The Earth has seasons because the north/south axis points toward or away from the sun as the year progresses. Winter has the shortest days, summer has the longest. On the first day of spring and fall, the “equinox”, day and night is equal, 12 hours of daylight and 12 hours of darkness. To remember the Phases of the moon – think of “D-O-C” The moon looks different each night because it revolves around the Earth. Since the moon does not make its own light (it reflects light from the sun), we see different phases. A lunar cycle takes 28 days (or 1 “moonth”). On the first day the moon can’t be seen from Earth. This is the new moon. During the next 14 days more light is seen each night, the moon is in the “waxing” phase. The tiny sliver of a waxing crescent looks like the outside of a “D”. On the 7th night, one-half of the moon can be seen, it is the 1st Quarter. The phases just before and after the full moon are called the gibbous phases. On the 14th night the entire disc of the moon can be seen in the full moon, it then looks like the Letter “O”. From here on out the moon will be losing light each night and it begins the phases of the waning Gibbous, the 3rd Quarter, and the waning crescent “C” . On the 28th day it can’t be seen in the new moon phase and the “moonth” is complete. Sun The Moon is in the waxing crescent phase in this photograph. The moon rises an hour later each day, so during some phases in the 28-day lunar monthly cycle (which I call a "moonth"), it can be seen early in the afternoon. An easy way to tell where the moon is in the cycle is to think of "D-O-C". At the beginning of the 28day "moonth" there is a New Moon, which is between the sun and the Earth and it can't be seen. Each day as the moon continues its' revolution (orbit) around the earth, a little more light is added, this is called a waxing moon. The first sign of the moon is the crescent moon, with a tiny sliver of light visible on the right. Waxing Crescent Moon – “D” K. Light First Quarter K. Light On around the 7th day of the "moonth" the moon is 1/4th into the revolution and half of the moon is visible, called the first quarter. The light is visible from the right side, like the edge of a "D". By the way, this is the best time to view the moon through a telescope or binoculars, it is up early enough in the evening and the craters are easy to see on the edge. Waxing Gibbous The next phase is the "almost full" phase called a gibbous moon. K. Light Full Moon – “O” K. Light On day 14 the moon is full, it then looks like an "O". The full moon reflects the light from the sun back toward the earth, it doesn't make its' own light. The moon rotates so slowly that only one side can be seen from the earth. We have never seen the back side of the moon except from an orbiting spacecraft. The gray areas seen here are called mare (mah-ray), meaning “sea” in Latin. They are lava beds from ancient eruptions. The surface of the moon is covered in craters made by meteorites. Since the moon has no atmosphere or weather, the surface does not change unless it has been struck by foreign objects (or spacecraft from Earth!). Waning Gibbous After the full phase, the moon begins to lose light every night. It then begins the waning phase. K. Light Third Quarter Moon K. Light By day 21, it is in the 3rd quarter phase and half of the moon is visible from the left side. It can be seen very late at night and into the early morning. Waning Crescent – “C” By day 25, it is in the waning crescent phase and a sliver of the moon is visible from the left side. It can be seen very late at night and into the early morning. The faint ring next to the bright part of the moon in this picture is called gegenschein, it is light reflected to the moon from the Earth. K. Light New Moon At the beginning and end of the “moonth” the moon is between the earth and sun and it can’t be seen from earth. The light shines on the “back side” of the moon. A Solar Eclipse occurs only during a New Moon Moon’s shadow If the moon is in the correct plane between the earth and sun it will block the light of the sun, causing an eclipse.The Moon’s shadow zooms around the earth at 1000 miles per hour as the Earth rotates! During “totality” the sun is completely blocked and people will see the stars for a short time. Never look at the sun during an eclipse! During a solar eclipse the moon blocks the sun Moon A Lunar Eclipse takes place only during a Full Moon When the full moon is in the correct plane, the earth blocks the sunlight and throws its shadow on the the moon causing a lunar eclipse. During a lunar eclipse the moon looks reddish because some of the Sun’s light bends around the earth. It is OK to look at a lunar eclipse because you are not looking at the sun. Map of the Moon The “seas” and “oceans” on the Moon do not contain water, they are large flat areas where lava flows occurred millions of years ago. The Sea of Tranquility is the location of the first manned Moon landing in 1969. Comet 17P / Holmes In October 2007, Comet Holmes put on a spectacular show by suddenly becoming much brighter over 3 days. A nucleus of the comet is a “dirty snowball” made of water ice, dry ice, dust and rock. It gives off gases, dust, and ions. This part is called the coma which is lit by the sun; comets do not make their own light. Comets orbit the sun like a planet, but usually with an oblong path out of the plane of the planets. Coma Algol – Nucleus a binary star in Perseus Comet Holmes K. Light The 8 Planets in our Solar System Pluto was designated a “dwarf planet” in August 2006 due to its small size and elliptical orbit. Follow-up Questions 1. What does the earth do when it revolves? 2. What does the earth do when it rotates? 3. Does the sun move through the solar system? 4. Why do we have seasons? 5. How many days is a “moonth”? 6. What is the moon doing if it is waxing? 7. Does the moon rise at the same time each day? 8. How much of the moon is visible during the 1st and 3rd Quarter phases? 9. What is a gibbous moon? 10. Where is the moon in relation to the earth and sun when it is full? 11. What are the mare on the moon? 12. Why can we see only one side of the moon? 13. Does the moon make its own light? 14. What is gegenschein? 15. How much of the moon is visible during a New Moon? 16. During what phase of the moon does a solar eclipse occur? 17. During what phase of the moon does a lunar eclipse occur? End of Presentation http://EastTennesseeWildflowers.com Kris Light ([email protected]) Photos for Purchase You can help support this site by purchasing my prints! For unique gifts or decorations for your home, office or cabin, check out the photos at: www.printroom.com/pro/klight Printroom will print and ship the orders to the customer. For more information on the moon phases, see the website gallery: http://www.easttennesseewildflowers.com/gallery/view_album.php?set_albumName=moon