I. Solar Eclipses

Moon passes exactly between Earth and sun:

• as moon orbits, shadow sweeps over Earth (Fig. 3-9)
• from Earth, watch moon slowly cover sun (Fig. 3-11)
• when in penumbra, see partial solar eclipse (http://antwrp.gsfc.nasa.gov/apod/ap001221.html)
• if in umbra, see total eclipse (http://www.mreclipse.com/SEphoto/SEpix.html)
• solar eclipse simulation: http://sunearth.gsfc.nasa.gov/eclipse/SEanimate/SE2001/SE2005Apr08H.GIF

What do you see during totality? (Fig. 3-12)

Why do people become eclipse chasers?

• Text describing eclipse (http://www.MrEclipse.com/Totality/TotalityCh01.html)

What if moon's shadow does not reach Earth?

• annular solar eclipse (Fig.3-13)
• Photo (http://antwrp.gsfc.nasa.gov/apod/ap980824.html)

When do Eclipses Occur? (Fig. 3-15,16,17)

Shouldn't eclipses occur at same month every year?

• eclipse season's shift (Fig. 3-18)

Eclipse predictions (http://sunearth.gsfc.nasa.gov/eclipse/SEcat/SEdecade2041.html)

• both time and place (Fig. 3-19)

Notes on eclipse expeditions from Mr. Eclipse, including filter glasses.

II. Angles, Distance and Size

• Physical size (in inches, miles, km,...) = s
• Angular size (in degrees, arcmin, or arcsec) = A
• Distance (in inches, miles, km,...) = d

What was relation b/w angular size & distance?

• graph looks like y = 1/x,
• that is, ang diam = 1/distance.

How does physical size factor in?

• from a fixed distance,
• double physical size makes double angular size.

• A = angular size of object (in arcsec!)
• d = distance from you to object
• s = physical size (in same units as d!)
• Examples ... Bring your calculator! <<<<<<<<<------

• Secs. 2-4 (pp. 21-25) and 4-1 (pp. 51-60).