Astronomy: Moon & Constellations

Table of Contents

• Teaching Tips: Phases of the Moon; Observing Constellations
• Noteworthy Scientist: Galileo Galilei (1564-1642)

Teaching Tip: Phases of the Moon

Unlike the sun, the moon does not give off its own light; instead it reflects the sun's light.  Because of the orbit of the moon, we don't always see the whole moon illuminated. How much of the moon we see depends on the phase it is in. Over the course of a month, you can observe all the different phases. A great way to teach your children about this is to observe the moon every few nights and discuss which phase it is in. If you have binoculars or a telescope, be sure to use them in your observation! During the month, what other changes do you notice? Does the moon always appear to have the same color and size? Your kids might enjoy keeping a journal with sketches and observations of each stage.

There are eight main phases in the moon's monthly cycle:

New Moon-the sun, moon, and earth are lined up, with the sun's light reflecting off the side of the moon facing it. To the earth on the other side of it, the moon appears to be very dark at this stage.

Waxing Crescent-the stage between the new moon and first quarter; a sliver of brightness is visible on the right. The dark part of the moon is still what is most visible to Earth at this point.

First Quarter-the moon is to the left of the earth and sun (moving counter-clockwise); the sun's rays shine on the half of the moon facing it, half of which is visible to Earth. Thus, it appears to be a "half moon," half bright and half dark.

Waxing Gibbous-the stage between the first quarter and full moon, when most of the bright side is visible.

Full-the sun, earth, and moon are lined up, with the side of the moon facing the earth illuminated.

Waning Gibbous-occurs after the full moon; the right edge appears to be dark or invisible. The moon is in the position opposite where it is during its waxing gibbous stage.

Last (Third) Quarter-the moon is to the right of the earth and sun; because the sun's light only falls on the side of the moon facing it, there also appears to be a "half moon" in this phase. The side that is bright is now opposite where it was during the first quarter, since the moon is on the other side of Earth.

Waning Crescent-occurs between the last quarter and the new moon; only a crescent of the bright side shows, on the left edge closest to the sun. The rest of the moon facing us is dark.

For younger children, you might want to demonstrate the moon's phases with a ball and flashlight in a dark room. See if you can determine how to arrange the ball (representing the moon), flashlight beam (sun), and a stationary audience (the earth) in the correct order to see the phases of the moon.

To quiz your knowledge of the moon's phases, visit http://starchild.gsfc.nasa.gov/docs/StarChild/solar_system_level2/moonlight.html

For an animation showing the moon's position relative to the sun and earth during each of its phases, visit http://www.sumanasinc.com/webcontent/anisamples/astronomy/moonphase.html

Teaching Tip: Observing Constellations

Observing the stars can be a fascinating and rewarding occupation. We have the opportunity to see the glory of God reflected in the heavens!

Some useful tools for your observations are a star chart, compass, and binoculars. If your star chart does not glow in the dark, you will probably need a flashlight, as well. If possible, cover the flashlight with red cellophane, since red light is not so distracting to your nighttime vision. To enhance your view of the stars, try getting as far away from bright lights as possible-if you live in the city, a park might make a good observation point.

Constellations change with the seasons because of the earth's rotation around the sun, so the stars that are visible to us vary from month to month. A good introduction to the study of the stars would be to observe the following constellations, which should be visible during November and early winter. You can download a good quality star chart at www.skymaps.com/downloads.html

Andromeda. "The Princess", "The Chained Maiden". The mythical Andromeda was an African princess, who was to be sacrificed to a sea monster in order to pacify the angry gods. She was rescued by Perseus and became his wife.

Cassiopeia."The Queen". The mythical character whom this constellation derives its name from was the mother of Andromeda. She aroused the anger of the gods by boasting of her beauty.

Pegasus. "The Winged Horse". The Pegasus supposedly sprang up from the blood of the many-headed Medusa, who was killed by Perseus.

Pisces. "The Fish". The ancient Babylonians, Greeks, and Persians all called this constellation by their name for "fish".

Pleiades. "The Seven Sisters", located in the constellation Taurus. Ancient Greek sailors would not set sail unless this cluster of stars was visible; if they could not see it, it meant bad weather was forthcoming.

Aquila. "The Eagle." This constellations figures in Greek, Hindi, Japanese, Korean, and Chinese mythology.

Ursa Minor (Little Dipper). The North Star (Polaris) is at the tip of the "handle".

Perseus. "The Hero". The mythical character Perseus was a Greek who rescued the Princess Andromeda from the sea monster, Cetus. This constellation is most clearly visible in December.

Orion. "The Hunter". This constellation was mentioned in The Odyssey. It is most visible in the winter (January).

Betelgeuse. A star in the Orion constellation. Its name, which comes from the Arabic for "house of twins", is pronounced like "BET-el-jooze".

Ursa Major (the Big Dipper). It probably is not highly visible during the fall or winter.

Noteworthy Scientist: Galileo Galilei (1564-1642)

The great Italian scientist and mathematician, Galileo Galilei, was born in 1564. In 1589 he taught mathematics to students in his hometown of Pisa and in 1591 he moved to Padua where he held a professorship in mathematics. His interests, though, extended to other branches of science, including mechanics, magnetism, and astronomy. Among his inventions are a hydrostatic pump, geometric compass, thermoscope, and an improved model of microscope.

However, the discoveries that Galileo is most known for are in the field of astronomy. He made his own telescope, with a higher magnification power than the other telescopes of the day. In 1610, Galileo published Sidereus Nuncius (Message from the stars), a work in which he set forth his observations on sunspots, the moon's physical geography, the phases of Venus, and his discovery of the moons of Jupiter. These discoveries supported the Copernican system of the universe: Copernicus had developed a heliocentric theory in which the sun was at the center of the universe, and the earth, planets, and stars were located in spheres around it. There were still some "bugs" to be worked out-for example, Copernicus and Galileo believed that the earth and other heavenly bodies orbited the sun in a prefect circle, rather than an ellipse-but it was the forerunner of the system that is held today.

In 1632 Galileo wrote his Dialogue concerning two great world systems, a fictitious dialogue between three men, discussing the merits and problems of the heliocentric Copernican and geocentric Ptolemaic view of the universe. The work was condemned by the Roman Catholic Church, who felt that Galileo was going too far by presenting the Copernican theory as fact. Not only the church, but also many of the scientists of the time, felt that the heliocentric theory of the universe was a faulty one. Galileo was placed under house arrest for the rest of his life. In 1636, he wrote a Dialogue on two new sciences, concerning the laws of motion. He is the first to have suggested that all bodies fall at the same rate if there is an absence of opposing force.

Website artwork, text and images Copyright © 2009 Home Training Tools, Ltd. All rights reserved.