The Sun and Moon

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Motion and Phases of the Moon
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3rd quarter
sunrise
noon
midnight
sunset
new
full

• Moons phase position in sky
• ? Time

1st quarter
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http//www.csulb.edu/gpickett/ps112_ems.html
http//www.astro.psu.edu/users/kluhman/a5/Lunar_Na
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Phases of the Moon
The Moon reflects light from the Sun, so its
phase tells you the relative position of the
Sun. You can therefore tell time from the Moon!
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Phases of the Moon
Full Moon occurs when the Moon is opposite in the
sky from the Sun. This is called
opposition. New Moon occurs when the Moon is in
the same direction as the Sun, i.e., in
conjunction.
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Solar Eclipses
Sun
planet
moon
Depending on the relative sizes and distances of
the Sun and a moon, you might see an eclipse like
this
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Solar Eclipses
Sun
planet
moon
Or you might see an eclipse like this
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Solar Eclipses
Sun
planet
moon
In our case, the Sun is 400 times larger than the
Moon, and coincidentally is also 400 times
further away, so they happen to have the same
size on the sky
http//www.astro.psu.edu/users/kluhman/a5/Eclipses
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Solar Eclipses
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Solar Eclipses
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Total Solar Eclipse
You only get to see this outer atmosphere
(corona) of the Sun if the Suns entire body is
blocked out.
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Solar Eclipses
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Partial Solar Eclipse
If youre on the edge of an eclipse path and only
a slice of the Sun is blocked out, its called a
partial eclipse. These are not very exciting,
since the uneclipsed part of the Sun is still
extremely bright.
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The Moons orbit is not a perfect circle, so its
distance from the Earth varies by a small amount,
and so does its size on the sky
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Annular Eclipses
Because the Moons orbit about the earth is not
perfectly circular, it is sometimes too far away
to block out the whole Sun, even when perfectly
aligned. When this happens, you get an annular
eclipse. It is rarer than a total solar eclipse.
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Shadows of the Earth and Moon
The Moons orbital plane is tilted by 5.2 from
the ecliptic plane. Hence, ½ the time, the Moon
is slightly north of the ecliptic (and ½ the
time, it is south of the ecliptic). The shadow
of one body very rarely falls on the other.
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Shadows of the Earth and Moon
The Moons orbital plane is tilted by 5.2 from
the ecliptic plane. Hence, ½ the time, the Moon
is slightly north of the ecliptic (and ½ the
time, it is south of the ecliptic). The shadow
of one body very rarely falls on the other.
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Lunar Eclipses
If the Moon crosses the ecliptic plane while
exactly opposite the Sun, it will fall in the
earths shadow. This is a lunar eclipse. It can
be seen from anywhere on the half of the Earth
facing the Moon.
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Frequency of Eclipses

• Under the most favorable conditions, the diameter
  of the shadow of a solar eclipse is 269 km at the
  Earths surface.
• At the equator, the shadow moves at 1730 km/hr.
• Totality can last as long as 7½ minutes.
• A total solar eclipse occurs about once every 18
  months somewhere in the world.
• At any given location, a total solar eclipse
  occurs once every 360 years.
• The next total solar eclipse in the U.S. is on
  Aug. 21 2017
• Lunar eclipses happen about twice each year. They
  are more common than solar eclipses because the
  earth is larger than the Moon and casts a larger
  shadow.

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Solar Eclipse Paths through 2020
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Columbus and the Lunar Eclipse

• In 1503, on his 4th voyage to the New World,
  Christopher Columbus and the crew of the Capitana
  were stranded in Santa Gloria Bay on the island
  of Jamaica.
• The natives refused to trade food and supplies
  for trinkets after Columbus became arrogant and
  overbearing.
• Columbus consulted Johannes Mullers Calendarium
  and saw that a total lunar eclipse would be
  visible on Feb. 29, 1504.

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• Columbus arranged an evening meeting with the
  natives and announced that his god would show his
  displeasure by taking away the moon.

• When the moon began to disappear, the frightened
  natives pleaded for Columbus to intervene.
• He retired to his cabin, and returned just before
  the end of the eclipse and announced that his god
  would restore the moon if they would supply
  Columbus and his crew.
• The natives supplied them with food until
  Columbus and his crew were rescued in June 1504.