Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
The Sun-Earth-Moon System Ms. Barry Earth and the Universe ▶ Earth is one of eight planets that orbit the Sun. ▶ The Sun is one of billions of stars that make up the Milky Way galaxy. ▶ The Milky Way is one of billions of galaxies in the universe. The Scale of the Solar System ▶ ▶ The Sun is 100x wider than Earth and 10x wider than the planet Jupiter. The Sun and Jupiter are the two largest objects in the solar system. Motions of the Earth ▶ Earth’s orbit is nearly round, or elliptical. ▶ The orbit of an object around another object is revolution. ▶ It takes Earth 365.25 days, or one year, to revolve around the Sun once. Measuring Distance ▶ An astronomical unit (AU) can be used to measure distances to objects in the solar system. ▶ An AU is the average distance between Earth and the Sun, approximately 150 million km. Day and Night ▶ ▶ ▶ ▶ ▶ Rotation is the spin of an object around its axis. Earth spins, or rotates, on its axis like a top. Earth’s rotation causes day and night. The side of Earth facing the Sun is in daylight. The side of Earth away from the Sun is in darkness. Earth makes one full rotation every 24 hours. The Moon ▶ Gravity holds the Moon in orbit around Earth. ▶ ¼ the size of the earth ▶ The Moon rotates on its axis, and revolves around Earth, orbiting Earth once every 27.3 days. ▶ Because the Moon revolves and rotates in the same amount of time, the same side of the Moon always faces Earth. The Phases of the Moon ▶ The Moon is visible because it reflects sunlight. ▶ The Moon completes a cycle of phases every 29.5 days. ▶ The moon’s axis is tilted, so it is not usually blocked by the earth Eclipses ▶ An eclipse is the movement of one solar system object into the shadow of another object. Solar Eclipse ▶ During a solar eclipse, a small part of Earth is in the Moon’s shadow. ▶ The Moon appears to completely or partially cover the Sun. ▶ This can only occur during a new moon Lunar Eclipse ▶ During a lunar eclipse, Earth’s shadow completely or partially covers the Moon. ▶ This can only happen during a full moon Earth’s Tilt and Seasons ▶ Seasons occur because Earth’s tilt does not change as Earth orbits the Sun. Summer and Winter ▶ When the northern hemisphere is tipped toward the sun, it experiences summer ▶ Sunlight is more intense ▶ When the northern hemisphere is tipped away from the sun, it experiences winter ▶ Sunlight is less intense Tides ▶ Tides are the rise and fall of the oceans caused by the gravitational force between Earth, Moon, and Sun. ▶ The Moon has more influence on tides than the Sun because it is closer to Earth than the Sun. Spring Tides ▶ ▶ ▶ Caused by the extra gravitational pull from the moon and sun when they are all in line High tides are higher than usual. Occur during full moon and new moon phases. Neap Tides ▶ The gravitational pull of the Moon is perpendicular to the gravitational pull of the Sun. ▶ High tides are lower than usual ▶ Occur during first and third quarter moons Equinox ▶ An equinox occurs when the sun is shining directly at the equator ▶ Occurs twice each year. These two days signify the beginning of spring and fall. Solstice • A solstice occurs when the Earth’s rotation axis is tilted directly toward or away from the Sun • North Pole is toward the Sun = summer in the northern hemisphere. • South Pole is toward the Sun = winter in the northern hemisphere.