Astronomy Astronomy the study of the planets, stars, galaxies, and all other objects in space. Horsehead Nebula

Motions of the Earth and Moon Globe – three dimensional model of Earth Earth’s axis is an imaginary line that runs from its North Pole, through its center, to its South Pole. Rotation – each complete counter-clockwise spin around the axis takes about 24 hours (a day) Revolution – Earth moving around the sun (a year) 365 days, 5 hours, 48 minutes, and 46 seconds

Earth is tilted at an angle of about 23.5º Earth’s tilt and revolution around the sun produces seasons. Solstices = when Earth is most tilted toward the sun Equinoxes = when Earth is not tilted toward the sun

Moon Phases – different shapes that the moon appears to have. The moon goes through 8 phases as it revolves around Earth once every 27.3 days.

Solar Eclipse = moon casts a shadow on Earth

Lunar Eclipse = Earth casts a shadow on the moon

Tides = changes in ocean water levels that take place in a regular pattern. (pull of gravity between moon and Earth. Tides usually change four times each day.

Solar System Objects Solar System – includes the sun and all objects in space that are affected by the sun’s gravity.

Sun -a medium size star -loses energy by emitting light

Terrestrial planets – four inner planets having rocky surfaces Mercury, Venus, Earth, and Mars

Gas giants – four outer planets that have surfaces made of a kind of slush that forms their gaseous atmospheres. Jupiter, Saturn, Uranus, Neptune

Gas giants are larger than the terrestrial planets. Scale model of sizes of planets

Moon = a natural satellite Satellite = object that stays in an orbit around a planet

Asteroid – large irregularly shaped rocks Comet – mixture of frozen gases and tiny particles of dust (tail points away from sun) Solar wind – particles from the sun Meteor – streak of light formed by a space rock burning up as it plunges into Earth’s atmosphere asteroid Comet Hale-Bopp Meteor Crater, Arizona