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opposite the sun, and leads to cycles of ocean tides and animal behavior. Its proximity fueled a space race and recognized the achievement of landing humans on another terrestrial object in our solar system. The moon is a truly remarkable aspect of our daily lives, whether we realize it or not.
Featured Resource Figure 2. Depiction of the moon’s orbit inclined relative to the Earth’s orbital
plane. Imagining the dotted line to circle around the Earth (into and out of the page) demonstrates that the nodes of possible eclipse would be found in front of the Earth as it circles out of the page and behind the Earth as it circles back into the page in this plane. Because this Earth-moon system together orbits
around the sun, there would be times when the sun would be facing into the page instead of from the left, allowing for eclipses to occur.
Additionally, when the orbital intersection occurs also plays a part in where the shadow is specifically cast upon the planet.
The last total solar eclipse to occur in the United States happened in February of 1979 and the next one is expected in April of 2024 (with a partial solar eclipse in 2023) (Debebe, n.d.b). There have been partial solar eclipses in the past couple of decades; to name a few examples, partial or annular solar eclipses were seen from some places in the continental United
Unsurprisingly, the featured resource this time is the National Aeronautics and Space Administration’s (NASA’s) moon website, where visitors may delve deeper into our collec- tive knowledge about, and historical exploration of, our nearest celestial neighbor:
https://www.nasa.gov/moon
References
Bell II, E. (2017, March 21). Luna 10. Retrieved from https://
nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1966-027A
Canup, R.M. (2012). Forming a moon with an Earth-like composition via a giant impact. Science, 338(6110), p. 1052- 1055.
Debebe, A. (n.d.a). What happens more often, solar or lunar eclipses? Retrieved from
https://eclipse2017.nasa.gov/what- happens-more-often-solar-or-lunar-eclipses
Debebe, A. (n.d.b). When was the last solar eclipse seen…? Retrieved from
https://eclipse2017.nasa.gov/when-was-last- solar-eclipse-seen-contiguous-united-states-and-when-will- next-one-happen
Hoang, C. (2017, August 20). 10 things: Aug 21 eclipse! Retrieved from
https://solarsystem.nasa.gov/ news/2017/08/20/10-things-aug-21-eclipse
Planetary Science Institute. (2017). Origin of the moon. Retrieved from
http://www.psi.edu/epo/moon/moon.html
Figure 3. Diagram of the shadows cast upon the Earth or moon during the types of eclipses.
States in October 2014, May 2012, and 2005 (Young, 2013). What makes the August 2017 solar eclipse special is that it passed from the west coast of the United States to the east, providing most places in the country a view of at least a partial solar eclipse; the next to do so, just as the last, will be about 100 years distant.
When the moon intersects the plane of the Earth’s orbit during the full moon phase, a lunar eclipse occurs, so-named because the moon is darkened by passing into the shadow of the Earth. Since the width of Earth’s shadow in space at the orbital distance of the moon is much larger than the moon’s shadow falling upon the Earth during a solar eclipse, the duration of the totality – the time the entire sun or moon is totally darkened – is much longer (an hour versus a few minutes). The larger shadow size also means that about half the planet sees a lunar eclipse when it happens, rather than just select portions. About 3 lunar eclipses occur every year. During the totality of a lunar eclipse the moon turns a dark red color, instead of black or invisible, because some sunlight is bent around the Earth through the atmosphere – depleted in blue wavelengths due to scattering, leaving just oranges and reds – and cast upon the moon.
Summation
The moon is an important companion to the Earth, inter- cepting potential impactors before they reach Earth, and sta- bilizing our planet’s axial tilt, moderating our seasonality and climate. Its presence provides, at times, a nightlight to shine
40 TPG •
Oct.Nov.Dec 2017
Pogge, R.W. (2008, January 21). Lecture 8: Phases of the moon – why are they different? Retrieved from http://www.
astronomy.ohio-state.edu/~pogge/Ast161/Unit2/
phases.html
Spudis, P.D. (2003). Chapter 10: The moon. In Beatty, J.K., Petersen, C.C., & Chaikin, A. (Eds.) (1999). The new solar system (4th ed.). Cambridge, MA: Sky Publishing Corporation.
Wood, C.A. (1999). The modern moon. Cambridge, MA: Sky Publishing Corporation.
Young, A. (2013, December 9). Solar eclipses 2011-2020. Retrieved from
https://eclipse.gsfc.nasa.gov/SEdecade/ SEdecade2011.html
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