Download Earth Time, Moon Phases and Eclipses

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
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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
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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
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The next phase is
the "almost full"
phase called a
gibbous moon.
K. Light
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Full Moon – “O”
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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
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After the full phase, the
moon begins to lose light
every night. It then
begins the waning phase.
K. Light
Third Quarter Moon
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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”
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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
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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
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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
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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
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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])
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For more information on the moon phases, see the website gallery:
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http://www.easttennesseewildflowers.com/gallery/view_album.php?set_albumName=moon
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