Physics 101 Astronomy Day 3 notes Motion of the Moon, phases of the Moon, and eclipses of the Moon and Sun

Motion of the Moon and Phases of the Moon The development of the current model of the solar system began with careful measurement of the movement of the Sun and the Moon. To understand this, let’s review the motion and the phases of the Moon, as we currently understand them. When we watch the Moon, it’s shape changes from one night to the next:

From the astronomy picture of the day web site ( link )

Earth and Moon, separately From Apollo 17 spacecraft From Earth

Earth and Moon, in one picture from the Galileo space probe as it traveled by the Earth on its way to Jupiter.

Lunar Phases

Lunar Eclipse

Lunar Eclipse

Solar Eclipse

Solar Eclipse over China

Solar Eclipse over Zambia sequence of photos superimposed to show the movement of the Sun

Solar Eclipse over Antarctica

Solar Eclipse – composite picture

Solar Eclipse – composite picture (cropped)

Solar Eclipse Types

Penumbra and Umbra

Classroom demonstration of umbra and penumbra Use a large shop light, to get a uniform spherical source of light. Then use a round (or even square) object and look at the shadow at various distances from source or screen. (the next screen is black, in order to get a dark room for the demonstration).

Shadow of Moon seen from Mir space station

Animation of Moon eclipsing the Sun, as seen from inside the umbra.

Animation of the view from the dark side of the Moon, looking down on the Earth during a solar eclipse.

Eclipse geometry is favorable when the Earth, Moon, and Sun are lined up. This happens when the intersection of the orbital planes passes through the Sun. See below.

Eclipse Tracks (also see Mr. Eclipse )

Web page at NASA devoted to this eclipse (link)

Example of a map of the eclipse path, showing the center line and boundaries of the region under the umbra (total) For the total eclipse of 29 March 2006

A useful website for eclipses is eclipsewise.com http://www.eclipsewise.com/oh/ec2017.html Scroll down the page to see eclipses for 2018. In 2018, there are three partial solar eclipses and two total lunar eclipses: 2018 Jan 31: Total Lunar Eclipse 2018 Feb 15: Partial Solar Eclipse 2018 Jul 13: Partial Solar Eclipse 2018 Jul 27: Total Lunar Eclipse 2018 Aug 11: Partial Solar Eclipse

Transits occur when a planet crosses between the Earth and the Sun, so we see a dark spot cross the Sun. This can only happen with Venus link or Mercury link. Occultations occur when the Moon blocks out (occults) a planet. Link

The Openstax book covers lunar phases and eclipses in Sections 4 The Openstax book covers lunar phases and eclipses in Sections 4.5 and 4.7. You should also read the chapter summary.