Earth

1
Earths Moon
2
Moon Factoids

• A blue moon is when more than one full moon
  occurs in the same calendar month.

• The moon undergoes synchronous rotation and
  revolution (i.e. the periods of rotation and
  revolution are identical), so one side of the
  moon always faces the Earth.

• The harvest moon involves the rising of the
  full moon in late September and early October.
  Due to the angular tilt of the moons orbital
  plane with that of the Earth, the bright moon
  appears to rise at about the same time in the
  early evening when the moon is full at the time
  of the autumnal equinox.

3
Motion of the Moon

• Moons Revolution
• One month
• Moons Rotation
• One month
• We ALWAYS see the same side of the moon.

4
Lunar Phases
5
Shadows and Eclipses
Sun
Penumbra Umbra
Earth

• An eclipse occurs when the Earth or the moon
  temporarily blocks the sunlight reaching the
  other.
• Eclipses can only occur when the sun, moon and
  Earth are perfectly lined up.

6
Eclipse of the Moon (Lunar Eclipse)
Occurs when the Earths shadow falls on the moon.
Earths Orbit Moons Orbit
Occurs during the Full Moon is also at the line
of nodes of its orbit with respect to the
ecliptic
A lunar eclipse lasts for many hours and can be
seen by anyone on the nighttime side of the Earth.
7
Eclipse of the Sun (Solar Eclipse)
Occurs when the moon moves directly between the
sun and the Earth and casts a shadow on part of
the Earth
Earths Orbit Moons Orbit
Occurs during the New Phase.
A solar eclipse lasts for only for a few minutes
and can only be seen from very restricted
locations on the Earths surface.
8
Example of a Solar Eclipse Path
See Richard Monks webpage on eclipses www.willia
ms.edu/ astronomy/IAU_eclipses/
9
Total Solar Eclipse of 21 June 2001 from Zimbabwe
See Richard Monks webpage on eclipses www.willia
ms.edu/ astronomy/IAU_eclipses/
Baileys Beads
Solar Corona
Diamond Ring
10
Lunar and Solar Eclipses
Solar Eclipses 7 Feb 2008
(annular) Australia Antarctica
1 Aug 2008 (total) Europe and Asia
26 Jan 2009 (annular) South Pacific
21 Jul 2009 (total) Asia Western
Pacific
Lunar Eclipses 21 Feb 2008
(total) U.S. 16 Aug 2008 (partial) not
U.S. 9 Feb 2009 (penumbral) not U.S. 7
Jul 2009 (penumbral) Western U.S. 5 Aug 2009
(penumbral) not U.S. 31 Dec 2009 (partial)
not U.S.
11
Origin of the Moon
12
Origin of the Moon

• The idea in a nutshell
• At the time Earth formed 4.5 billion years ago,
  other smaller planetary bodies were also growing.
  One of these hit earth late in Earth's growth
  process, blowing out rocky debris. A fraction of
  that debris went into orbit around the Earth and
  aggregated into the moon.

13
The Moons Interior
14
The Tides
4. On the far side, the Earth is effectively
pulled Moonward away from the water, yielding
another high tide.
3. The water on the near side of the Moon is
pulled away from Earth, raising a high tide.
Earth
Moon
2. The presence of the Moon produces a
gravitational attraction on the Earth whose
strength varies inversely with distance from the
Moon.
1. Imagine a perfectly spherical Earth uniformly
flooded by an ocean.