Looney Tunes

PTYS206-220 Feb 2008

Sizes and Distances

Diameter of Earth=12,756 km

Diameter of Moon=3476 km

Mass of Earth=6.0×1024 kg

Mass of Moon=7.4×1022 kg

Average Distance = 384,400 km

Scale Diagram

Phasesof theMoon

Figure from AstronomyToday by Chaisson andMcMillan

Moon Movie

Lunar Orbit

Apogee

Perigee

Lunar Orbit

Apogee = 406,720 km

Perigee = 356,375 km

Eccentricity = 0.05

Linguistics: apohelion - greatest distance fromsun (helios)

perihelion - smallest distance from

sun

apogee - greatest distance from Earth

perigee - smallest distance from Earth

Synchronous Rotation

Lunar Rotation and Orbital Motion• The moon orbits Earth once every

27.32 days. This is the siderealperiod

• The moon rotates on its axis withexactly the same period. This iscalled synchronous rotation. Themoon presents the same face tothe Earth at all times.

• Because the Earth is also rotating,it takes 29.53 days for the moonto return to the same location inthe sky. This is the synodicperiod.

• The moonʼs orbital period isgetting longer and its orbit largerby about 3 cm/year.

From Astronomy: from the Earth to the Universe byPasachoff

Eclipse Geometry

What does this photo tell you about thesize of the moon?

Remember to show solar eclipse movie

Geometry of Solar Eclipse

Remember to show lunar eclipse movie

Umbra is latin for “shadow”

Pen is a latin prefix that means almost, for examplepenultimate means next to ultimate

Penumbra means almost in shadow.

Linguistics

Why does the moon appear red duringa total eclipse?

Why can you see the moon at allduring a total eclipse?

Why don’t lunar eclipses happen everymonth?

Eclipses of the Moon: 2008 - 2015Date Eclipse Type Eclipse Duration Geographic Region of Eclipse Visibility2008 Feb 21 Total 03h26m 00h51m c Pacific, Americas, Europe, Africa2008 Aug 16 Partial 03h09m S. America, Europe, Africa, Asia, Aus.2009 Feb 09 Penumbral -0.083 - e Europe, Asia, Aus., Pacific, w N.A.2009 Jul 07 Penumbral -0.909 - Aus., Pacific, Americas2009 Aug 06 Penumbral -0.661 - Americas, Europe, Africa, w Asia2009 Dec 31 Partial 01h02m Europe, Africa, Asia, Aus.2010 Jun 26 Partial 02h44m e Asia, Aus., Pacific, w Americas2010 Dec 21 Total 03h29m 01h13m e Asia, Aus., Pacific, Americas, Europe2011 Jun 15 Total 03h40m 01h41m S.America, Europe, Africa, Asia, Aus.2011 Dec 10 Total 03h33m 00h52m Europe, e Africa, Asia, Aus., Pacific, N.A.2012 Jun 04 Partial 02h08m Asia, Aus., Pacific, Americas2012 Nov 28 Penumbral -0.184 - Europe, e Africa, Asia, Aus., Pacific, N.A.2013 Apr 25 Partial 00h32m Europe, Africa, Asia, Aus.2013 May 25 Penumbral -0.928 - Americas, Africa2013 Oct 18 Penumbral -0.266 - Americas, Europe, Africa, Asia2014 Apr 15 Total 03h35m 01h19m Aus., Pacific, Americas2014 Oct 08 Total 03h20m 01h00m Asia, Aus., Pacific, Americas2015 Apr 04 Total 03h30m 00h12m Asia, Aus., Pacific, Americas2015 Sep 28 Total 03h21m 01h13m e Pacific, Americas, Europe, Africa, w AsiaGeographic abreviations (used above): n = north, s = south, e = east, w = west, c = centrale