Earth and Moon Movements

The Solar System

• The solar system revolves around the sun.
• The sun is surrounded by planets that may have moons orbiting them.
• Our solar system includes Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto is considered a dwarf planet.
• Planets have different numbers of moons. Gas giants have the most.
• Astronomy is the study of the universe beyond Earth.
• Ancient civilizations studied the movements of the sun and the moon.

Earth's Movement in Space

• Earth rotates or spins on its axis causing night and day. The side facing the sun experiences day, while the side away experiences night.
• Earth completes a rotation every 24 hours.
• Earth's axis is tilted, causing seasons. The part tilted towards the sun is in summer; the part tilted away is in winter.
• Earth revolves around the sun. A year is defined by the time it takes Earth to make a complete revolution: $365.25$ days.
• The path Earth follows in its revolution is called its orbit, which is shaped like an ellipse.

Moon's Movement

• The moon rotates on its axis once every $27.3$ Earth days.
• The Moon revolves around the Earth in about $27.3$ Earth days.
• The same side of the moon always faces Earth.
• The phases of the moon are caused by the relative positions of the moon, Earth, and Sun.
• The moon reflects light from the sun, and half of the moon is always lit by the sun.

Phases of the Moon (Lunar Cycle)

• The lunar cycle begins with the new moon, which is not visible.
• Waxing Crescent: About one quarter of the moon is visible.
• First Quarter: Half of the moon is visible.
• Waxing Gibbous: Three quarters of the moon is visible.
• Full Moon: The entire surface of the moon is reflecting sunlight.
• Waning Gibbous: The part of the moon we observe decreases.
• Third Quarter: Mirror image of the first quarter.
• Waning Crescent: A sliver on the left side of an otherwise dark moon.

Eclipses

• An eclipse occurs when the moon's shadow covers part of the earth or when the earth's shadow covers part of the moon.
• Solar Eclipse: A new moon blocks the view of the sun.
  • A total solar eclipse occurs when the moon completely covers the sun's disk.
• Lunar Eclipse: The Earth is directly between the moon and the sun.
  • A total lunar eclipse occurs when the Earth's shadow completely covers the moon, causing it to look red.
  • A partial lunar eclipse occurs when only a portion of the moon enters Earth's shadow.

Tides

• Earth's tides are caused by the gravity of the moon and the sun.
• High tides occur in areas with more pull from either the sun or the moon.
• Low tides occur in areas with less pull from the sun or the moon.
• Spring Tides: During full and new moons, the sun, Earth, and moon are almost in perfect alignment, creating very high tides.
• Neap Tides: During the first and third quarter phases of the moon, the sun and the moon are at right angles, creating lower high tides and higher low tides.