Eclipses Created by the Lunar and Planetary Institute and Mrs. Moore. This powerpoint compiled by the Education Staff at the Lunar and Planetary Institute www.lpi.usra.edu http Sept. 2009, triple eclipse on Jupiter, near-infrared telescope on Hubble s://www.space.com/16024-venus-transit-2012-skywatchers-rejoice.html Created by the Lunar and Planetary Institute and Mrs. Moore.

Preliminary Ideas: The Moon orbits the Earth in 27.3 days. The Moon orbits at an angle (roughly 5⁰) with respect to the Earth’s orbit around the Sun. The moon is not in the same orbital plane as the Earth. 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.

Preliminary Ideas The Moon & Earth do not produce their own light. We see phases of the Moon from Earth. The Moon is smaller than Earth. 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.

Moon Size Earth radius = 6378.1 km Moon radius = 1737.4 km ~1/4 size of Earth ~1/6 of Earth’s gravity Earth’s radius = 6378 kilometers or 3963 miles Moon’s radius = 1738 kilometers or 1080 miles Earth image from http://grin.hq.nasa.gov/IMAGES/SMALL/GPN-2000-001444.jpg http://grin.hq.nasa.gov/IMAGES/SMALL/GPN-2000-001444.jpg

1. Earth and Moon to Scale If Earth were a basketball, then the Moon would be a tennis ball ……….. 23.5 feet away. From http://visibleearth.nasa.gov/view_rec.php?id=1624 This image conveys the distance between Earth and Moon. You can demonstrate a scale model to your audience by providing one of your participants with a tennis ball (Moon) and one with a basketball (Earth).  Ask the audience to determine how far apart the two balls should be about 24 feet. Original Caption Released with Image: 2001 Mars Odyssey's Thermal Emission Imaging System (THEMIS) took this portrait of the Earth and its companion Moon, using the infrared camera, one of two cameras in the instrument. It was taken at a distance of 3,563,735 kilometer s (more than 2 million miles) on April 19, 2001 as the 2001 Mars Odyssey spacecraft left the Earth. From this distance and perspective the camera was able to acquire an image that directly shows the true distance from the Earth to the Moon. The Earth's diameter is about 12,750 km, and the distance from the Earth to the Moon is about 385,000 km, corresponding to 30 Earth diameters. The dark region seen on Earth in the infrared temperature image is the cold south pole, with a temperature of minus 50 degrees Celsius (minus 58 degrees Fahrenheit). The small bright region above it is warm Australia. This image was acquired using the 9.1 µm infrared filter, one of nine filters that the instrument will use to map the mineral composition and temperature of the martian surface. From this great distance, each picture element (pixel) in the image corresponds to a region 900 by 900 kilometers or greater in size or about size of the state of Texas. Once Odyssey reaches Mars orbit each infrared pixel will cover a region only 100 by 100 meters on the surface, about the size of a major league baseball field. http://visibleearth.nasa.gov/view_rec.php?id=1624

2. Causes of Moon Phases The Sun shines on the Moon all of the time. Only the side facing the sun receives sunlight. From Earth’s perspective, the amount of moon we see lit up changes as the Moon orbits around Earth. 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 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. http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question3.html

Also from StarChild: http://starchild. gsfc. nasa starchild.gsfc.nasa.gov/docs/StarChild/questions/phases.html

3. What is an Eclipse? An eclipse occurs when one astronomical body such as a moon or planet moves into the shadow of another astronomical body. Eclipses involve shadows. 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.

4. Shadows Shadows are formed when light is obstructed (or blocked). The light may be totally obstructed thereby forming a dark shadow known as an Umbra. Or it may be partially obstructed thereby forming an outer gray shadow known as a Penumbra. Penumbra (gray) Umbra (black)

Umbra/Penumbra demo

5. Lunar Eclipses When the Earth’s shadow covers the Moon, we have a lunar eclipse. http://www.mreclipse.com/Special/LEprimer.html Additional details are at http://en.wikipedia.org/wiki/Lunar_eclipse

Lunar eclipse shadows – label on your diagram: Umbra Penumbra

A. Three types of Lunar Eclipses 1) Penumbral lunar eclipse—the Moon only passes through the penumbra of Earth’s shadow.

Three types of Lunar Eclipses 2) Partial lunar eclipse—part of the Moon passes through the umbra of Earth’s shadow.

Three types of Lunar Eclipses 3) Total lunar eclipse—entire Moon passes through the umbra of Earth’s shadow.

Lunar eclipse shadows

4) Who on Earth will be able to see a lunar eclipse of any type? Anyone who can see the Moon; sky conditions must be clear.

5) When is the next lunar eclipse? 2016 Mar 23 11:48:21 Penumbral - Asia, Aus., Pacific, w Americas 2016 Sep 16 18:55:27 Europe, Africa, Asia, Aus., w Pacific 2017 Feb 11 00:45:03 Americas, Europe, Africa, Asia 2017 Aug 07 18:21:38 Partial 01h55m Europe, Africa, Asia, Aus. 2018 Jan 31 13:31:00 Total 03h23m 01h16m Asia, Aus., Pacific, w N.America 2018 Jul 27 20:22:54 03h55m 01h43m S.America, Europe, Africa, Asia, Aus. 2019 Jan 21 05:13:27 03h17m 01h02m c Pacific, Americas, Europe, Africa Information at http://sunearth.gsfc.nasa.gov/eclipse/lunar.html

Images from Fred Espanak and may be found at http://www.mreclipse.com/LEphoto/LEgallery1/LEgallery1.html Images from Fred Espenak http://www.mreclipse.com/LEphoto/LEgallery1/LEgallery1.html

B. Why is the Moon red during a total lunar 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 Earth’s atmosphere.

www.weatherwisemagazine.org

NASA lunar eclipse summary

6. Solar Eclipses When the Moon moves in front of the Sun and Moon’s shadow covers part of Earth. Only happens at New Moon phase. Three types: Annular, Partial, and Total. Diagram from Fred Espenak, may be found along with lots of good information at http://www.mreclipse.com/Special/SEprimer.html

Solar eclipse shadows – label on your diagram

1) Annular Solar Eclipse When the Moon is too far away to completely cover the Sun—the umbra doesn’t reach the Earth. Sun appears as a donut or ring around the Moon. Diagram from Fred Espenak, may be found along with information at http://www.mreclipse.com/Special/SEprimer.html

Photos of an Annular Eclipse From http://sunearthday.nasa.gov/2006/multimedia/gal_010.php; photos taken by Fred Espenak http://sunearthday.nasa.gov/2006/multimedia/gal_010.php; photos taken by Fred Espenak

2) Partial Solar Eclipse Observers see only part of the sun covered. They are in the penumbral shadow. Not safe to look at sun! Diagram by Fred Espenak and more information may be found at www.MrEclipse.com

3) Total Solar Eclipse Observers in the umbra shadow see a total eclipse (safe to view the Sun); can see the sun’s corona. Only lasts a few minutes. Path of Totality about 10,000 miles long, only 100 miles wide. Diagram by Fred Espenak and more information may be found at www.MrEclipse.com

Path of Totality

Solar eclipse shadows

Total Eclipse From http://sunearthday.nasa.gov/2006/multimedia/gal_008.php http://sunearthday.nasa.gov/2006/multimedia/gal_008.php

4) Next Solar Eclipse in the USA: April 8, 2024 (Will be partial for Tucson, AZ)

5) Why doesn’t everyone in the USA see the solar eclipse?

Solar Eclipse from Space

Eclipse Tracks People at North and South poles only see partial solar eclipses.

NASA lunar eclipse summary

7. Tides While both the Moon and the Sun influence the ocean tides, the Moon plays the biggest role because it is so much closer to our planet than the Sun. Gravitational forces pull the water in the oceans upwards making the oceans bulge, which creates high tide in the areas of Earth facing the Moon and on the opposite side. At the same time, in the remaining areas of the planet, the ocean water drains away to fill these bulges, creating low tides. p.2 ended here. 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.

Tides and the Moon

Tidal pull animation <iframe width="420" height="315" src="https://www.youtube.com/embed/l37ofe9haMU" frameborder="0" allowfullscreen></iframe>

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