Chapter 1 Orbits

Earth and the Moon in Space The Earth and the moon create a system together. They revolve, or travel in a closed path, around the sun. We call Earth’s path an orbit.

Earth and the Moon in Space Earth’s orbit is an ellipse.

Earth’s Rotation Earth also rotates, or spins on its axis. The axis is an imaginary line passing through the center of Earth’s north and south poles.

Earth’s Rotation

The Moon’s Revolution The moon revolves around the Earth in an ellipse-shaped orbit because of gravity. Remember: The universal law of gravitation: all objects in the universe are attracted to all other objects in the universe.

The Moon’s Rotation The moon also rotates along its axis. It takes 27.3 days for the moon to complete one rotation on its axis.

The Moon’s Rotation The same side of the moon always faces Earth because it takes as long to orbit the Earth as it does for it to rotate on its axis.

The Moon’s “Light” The moon does not give off light; it reflects sunlight from its surface. As its position in the sky changes, we see different phases of the moon.

Chapter 1 The Seasons

The Seasons We split the year into four seasons: winter, spring, summer, and fall.

The Seasons As the Earth orbits the sun, the amount of sunlight shining on each place changes slightly. This causes the seasons.

Earth’s Tilt

Earth’s Tilt The Earth is tilted at 23.5 degrees. For half the year, the North is pointed more toward the sun, creating longer days with more sunlight. During this time, the Southern hemisphere has shorter days with less sunlight.

Earth’s Tilt The seasons are opposite on the Northern and Southern hemispheres. During the summer, the sunlight shines more directly on the surface of Earth, creating higher temps.

Earth’s Tilt During the winter, the sun hits Earth’s surface at an angle, creating less heat.

The Length of the Day In the Northern hemisphere, June 21st is the longest day and December 21st is the shortest day. March 21st (spring equinox) and September 21st (autumn equinox) have an equal amount of day and night.

Chapter 1 The Moon’s Features

The Moon’s Surface The surface formed from hot, molten rock that turned into a rocky crust when it cooled. The moon’s has three main features.

Highlands Areas of crust that are higher than the surrounding area; almost like a mountain.

Craters The moon has several large and small craters. Tycho is 54 miles across.

Maria “Maria” means “sea” Dark, flat areas made of hardened lava – basalt rocks. The largest mare is 775 miles across.

Earth and Moon Both rocky and dense. Both have craters, but the moon has more because meteorites burn as they enter Earth’s atmosphere.

Earth vs. Moon The moon has no atmosphere and no liquid water, but frozen water has recently been found. No erosion can occur by wind or water.

Chapter 1 The Moon’s Phases

The Phases There are 8 phases of the moon that we see throughout its 27.3 day cycle.

1. The New Moon The moon is between the Earth and the sun. It cannot be seen due to its position.

2. Waxing Crescent The moon is between the Earth and the sun. It cannot be seen due to its position.

3. First Quarter The moon is one quarter of the way around Earth. Looks like a half circle. One week into cycle.

4. Waxing Gibbous More of the sun’s light is reflecting off of the Earth’s surface.

5. Full Moon About two weeks into cycle, we see the entire sunlit part of the moon.

6. Waning Gibbous The moon is getting slightly “smaller” (less sun light is reflecting).

7. Last Quarter About three weeks into cycle. The moon is three-fourths of the way around Earth.

8. Waning Crescent The moon’s sunlit part is about to disappear. The moon’s cycle is almost complete.

The Moon’s Phases

Solar and Lunar Eclipses Chapter 1 Solar and Lunar Eclipses

What is an eclipse? Eclipse: when one object passes through the shadow of another. Eclipses can occur during a new moon or a full moon when the sun, the Earth, and the moon all line up.

Solar eclipses Occurs when Earth passes through a new moon’s shadow. The moon completely covers the sun. Only the sun’s outer atmosphere is visible.

Solar eclipses

Lunar eclipses Occurs when the full moon passes through the Earth’s shadow. The Earth blocks the sun’s light. Makes the moon appear to be red.

Lunar eclipses

Solar vs. Lunar Solar New moon Sun – moon – Earth Moon has light around it. Lunar Full moon Sun – Earth – moon Moon appears to be red.

Eclipses Only 7 eclipses (2 lunar and 5 solar) happen throughout the year. Most of these are only partial eclipses.

Exploring Space Technology and Time

Exploring the Solar System Thousands of years ago, people could only make observations using their eyes. They could see the phases of the moon and the moon’s larger features, but they did not have the technology to research further.

The Telescope invented about 400 years ago Allowed people to see objects in space in greater detail an instrument that magnifies (makes larger) distant objects.

The Telescope First used by an Italian scientist named Galileo. He saw the moon and its features much more clearly. he observed Venus and moons orbiting Jupiter.

The Telescope Sir Isaac Newton used a much better telescope about 50 years later to observe other objects in space. It used two mirrors and one lens. https://www.youtube.com/watch?v=EGtriSso6r0

The Telescope In 1936, the first radio telescope was built, detecting radio waves from outer space.

Satellites Modern space exploration began in 1957 with the launching of Sputnik I, an artificial satellite. satellite: any natural body or artificial object that orbits another object. Sputnik carried instruments to measure the density and temperature of Earth’s upper atmosphere.

Astronauts in Space 1961: first Americans in space 1969: the US landed the first person on the moon. Project Apollo landed 12 humans on the moon to set up experiments to get samples of rock from the moon.

Space Probes space probe: robot vehicle used to explore deep space. Voyager space probes have sent back pictures of the outer planets and is still traveling through space. Viking I and Viking II landed on Mars

Chapter 2 The Sun’s Energy

The Sun “Earth’s star” center of the solar system huge ball of very hot gases – hydrogen and helium source of almost all energy on Earth – for plants, animals, and wind.

The Sun’s Energy comes from the fusing, or combining, of small particles to form larger ones. the core of the sun has such high temps that, combined with pressure, hydrogen atoms smash into each other to form helium. This is called fusion and it releases light and heat.

The Sun’s Energy travels in waves. some waves are visible light. infrared waves = heat ultraviolet waves = tan/burn skin radio waves and X-rays

Exploring the Sun 1.4 km across 100 times the size of the Earth Closer to Earth than other stars Has several layers that blend together.

Exploring the Sun the layer in the middle is the core. It is the smallest part, but contains the most mass. Mass: the amount of matter in an object.

Exploring the Sun as energy moves out, it passes through the radiation zone. This zone is heated from the core. From there it moves to the convection zone, where convection moves energy to the sun’s surface.

Exploring the Sun

Exploring the Sun the surface is called the photosphere – “sphere of light” made of hot, bright areas called granules. Sunspots are dark areas on the surface. They are cooler than the rest of the sun. Solar flare: brief burst of energy from the surface – UV rays, radio waves, X-Rays.

Exploring the Sun The corona is the sun’s atmosphere – extends 1 million km from the surface. It is only visible during an eclipse. Streams of small particles, called solar wind, travel from the corona to the rest of the solar system. Can cause magnetic storms if they reach Earth.

Exploring the Sun

How Stars are Classified Chapter 2 How Stars are Classified

Star Magnitude How bright a star looks depends on: magnitude (brightness) and distance from Earth. If two stars have the same brightness, the one closer to Earth would seem brighter. Its apparent magnitude (how bright it seems) is less than its absolute magnitude (how bright it really is).

Types of Stars The color of a star is a clue to its surface temperature. Blue stars are the hottest, red stars are the coolest.

Types of Stars scientists use a chart that compares size, magnitude, temperature, and color. On this chart there is a main sequence: a band that runs from top left to bottom right of the chart that includes most stars. About 95% of stars.