1. Eclipses and
Lunar Phases
By the Lunar and Planetary Institute
For use in teacher workshops
http://solarsystem.nasa.gov/multimedia/gallery/Earth_Moon.jpg
2. Preliminary Topics
Before students can understand the
reason for phases, they need to
understand:
• The Moon orbits the Earth
Ecliptic plane
• The Moon orbit at an angle with respect to Moon’s orbital plane
the Earth’s orbit around the Sun
• The Moon doesn’t shine on its own; it reflects
sunlight
• The scale of the Moon and Earth’s sizes and
distance
Please go through Earth and Moon statistics
before trying to cover the reason for phases or
eclipses.
3. Phases:
Observing and Identifying
New (couple days)
Waxing Crescent (several days)
1st Quarter
Waxing Gibbous (several days)
Full
Waning Gibbous (several days)
3rd Quarter
Waning Crescent (several days)
New
http://www.lpi.usra.edu/education/skytellers/moon_phases/about.shtml
4. Phases--Causes
• The Sun shines on the Moon.
– When the sunlight reflects off the Moon’s
far side, we call it a New Moon
– When the sunlight reflects off on the
Moon’s near side, we call it a Full Moon
– Between New and Full, we see parts of the
daytime side of the Moon.
Golfball and Blacklight Activity
5. Please do NOT use this to teach phases;
use to test for comprehension
http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question3.html
7. Eclipses
• The Sun and Moon occasionally line
up so that we have an eclipse.
– These eclipses happen every year
– To see a solar eclipse, you need
to be on a particular part of the
Earth
9. Three types of Lunar Eclipses
• Penumbral lunar eclipse—the Moon only passes
through the penumbra of Earth’s shadow
• Partial lunar eclipse—part of the Moon passes
through the umbra of Earth’s shadow
• Total lunar eclipse—the entire Moon passes through
the umbra of Earth’s shadow
• Who on Earth will be able to see a lunar eclipse?
Anyone who can see the Moon (anyone who is on
the nighttime side of the Earth during the eclipse)
10. Images from Fred Espenak
http://www.mreclipse.com/LEphoto/LEgallery1/LEgallery1.html
11. Why is the Moon red during an eclipse?
• The Earth’s atmosphere filters some sunlight and
allows it to reach the Moon’s surface
• The blue light is removed—scattered down to make a
blue sky over those in daytime
• Remaining light is red or orange
• Some of this remaining light is bent or refracted so
that a small fraction of it reaches the Moon
• Exact appearance depends on dust and clouds in the
Earth’s atmosphere
13. Solar Eclipses
• When the Moon’s shadow covers part of the Earth
• Only happens at New Moon
• Three types: Annular, Partial, and Total
14. Total Solar Eclipse
• Observers in the “umbra” shadow see a total eclipse (safe to view the Sun); can
see the corona
• Those in “penumbra” see a partial eclipse—not safe to look directly at Sun
• Only lasts a few minutes
• Path of Totality about 10,000 miles long, only 100 miles wide
15. Photo of a Total Eclipse
http://sunearthday.nasa.gov/2006/multimedia/gal_008.php
16. Annular Solar Eclipse
• When the Moon is too far to completely cover the Sun—the umbra
doesn’t reach the Earth
• Sun appears as a donut around the Moon
17. Photos of an Annular Eclipse
http://sunearthday.nasa.gov/2006/multimedia/gal_010.php; photos taken by Fred Espenak
19. Tides
• The Moon’s gravity tugs on the Earth.
– It pulls the most on the part of Earth closest, which
raises the atmosphere, the oceans, and even the
rocks (a little)
– It pulls the least on the part of Earth that’s farthest,
which allows the oceans and atmosphere to be
further from the Moon (and higher)
– The Sun’s gravity does the same thing, but to a
lesser extent
Hinweis der Redaktion
This powerpoint compiled by the Education Staff at the Lunar and Planetary Institute www.lpi.usra.edu Image from http://solarsystem.nasa.gov/multimedia/gallery/Earth_Moon.jpg This picture of the Earth and Moon in a single frame, the first of its kind ever taken by a spacecraft, was recorded September 18, 1977, by NASAs Voyager 1 when it was 11.66 million km (7.25 million miles) from Earth. The moon is at the top of the picture and beyond the Earth as viewed by Voyager. In the picture are eastern Asia, the western Pacific Ocean and part of the Arctic. Voyager 1 was directly above Mt. Everest (on the night side of the planet at 25 degrees north latitude) when the picture was taken.
We highly recommend doing Earth and Moon statistics with workshop participants before doing this powerpoint, if you intend to discuss the reason for phases or eclipses.
Images from http://www.lpi.usra.edu/education/skytellers/moon_phases/about.shtml In some states, young elementary students may be required in their science standards to observe the changing patterns in the Moon’s appearance. Making observations part of the classroom assignments is a fundamental part of this; the students can bring in drawings of the Moon’s appearance on paper or on paper plates, and they can be placed on the wall over a period of 1-2 months. Students can also make phases out of Oreo cookies.
It is not appropriate for very young students to try to master the reason for phases; they often do not have the ability to imagine the three-dimensional nature of this. Many adults have fundamental misconceptions regarding the reason for the Moon’s phases. We conduct an activity with golfballs and blacklights in our workshop here, allowing participants to see “phases”.
From http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question3.html Full Moon rises as the Sun sets. The Full Moon is in mid-sky at Midnight. Full Moon sets as the Sun rises. Full Moon cannot be seen during the day.
Also from StarChild: http://starchild.gsfc.nasa.gov/docs/StarChild/questions/phases.html
Only after phases have been mastered should you try to teach the reason for eclipses; otherwise, students will often assume that the reason for the Moon’s phases is the Earth’s shadow. To understand why we have eclipses, we use the golfballs and blacklights, along with an embroidery hoop to model out the changing intersection of the Moon’s orbit with the ecliptic, as the Earth goes around the Sun.
http://www.mreclipse.com/Special/LEprimer.html Additional details are at http://en.wikipedia.org/wiki/Lunar_eclipse
Images from Fred Espanak and may be found at http://www.mreclipse.com/LEphoto/LEgallery1/LEgallery1.html
Information at http://sunearth.gsfc.nasa.gov/eclipse/lunar.html
Diagram from Fred Espenak, may be found along with lots of good information at http://www.mreclipse.com/Special/SEprimer.html
Diagram by Fred Espenak and more information may be found at www.MrEclipse.com
From http://sunearthday.nasa.gov/2006/multimedia/gal_008.php
Diagram from Fred Espenak, may be found along with information at http://www.mreclipse.com/Special/SEprimer.html
From http://sunearthday.nasa.gov/2006/multimedia/gal_010.php; photos taken by Fred Espenak
Information at http://sunearth.gsfc.nasa.gov/eclipse/solar.html
It's not a question of mass, but of energy! The tidal force exerted by the Moon on the Earth causes the oceans to bulge. The Earth rotates about its axis faster than the Moon revolves around the Earth, and this rapid rotation carries the tidal bulge of the oceans forward of the Moon in its orbit. So the tidal bulge on the Earth is always slightly ahead of the Moon's own position. This bulge is continuously tugging the Moon forward, increasing the Moon's total energy. Imagine a cowboy's lasso. As the cowboy spins the lasso faster and faster (increasing its total energy), the loop gets wider. The same thing essentially happens to the Moon. The tugging of the Earth's bulge lifts it into a wider orbit around the Earth.