EARTH IN SPACE

DAY AND NIGHT The Earth completes one rotation on its axis every 24 hours. The rotation of the Earth on its axis is responsible for day and night. The Earth rotates counterclockwise. The counterclockwise rotation is what makes the sun appear to rise in the east and set in the west.

SEASONS The Earth completes one counterclockwise revolution around the sun every 365 ¼ days. The revolution of the Earth around the Sun, along with a tilt of 23.5 degrees on its axis, is responsible for seasons on Earth.

SEASONS Shadows are shortest in the summertime and longest in the wintertime. The appearance of the shorter shadows is due to the sun being more directly overhead in the summertime.

THE MOON The apparent shape of the Moon in our sky depends on how much of the Moon’s illuminated side is visible from Earth. As the moon orbits (revolves around) the Earth, it goes through a predictable cycle of changes called phases.

THE MOON The Moon’s cycle is divided into eight equal parts:

THE MOON During the waxing moon, the illuminated portion is continually growing bigger (right side is lit). During the waning moon, the illuminated portion is continually growing smaller (left side is lit).

ECLIPSES An eclipse can occur when the Sun, Earth, and Moon align perfectly A solar eclipse can occur only during a new moon. A lunar eclipse can occur only during a full moon

ECLIPSES SOLAR ECLIPSE: Occurs during a new moon, when the Moon comes between the Sun and Earth and casts a shadow on part of the Earth.

ECLIPSES LUNAR ECLIPSE: Occurs during a full moon, when the Earth comes between the Sun and Moon and casts a shadow on the Moon.

THE SUN AS AN ENERGY SOURCE Radiation is the direct transfer of energy by electromagnetic waves Solar radiation is energy from the Sun. It is a major source of energy on Earth. The farther away an energy source, the greater its energy output must be to produce the same effect as a closer source. Earth and its atmosphere absorb and reflect the Sun’s radiant energy; the absorbed energy heats the planet and its atmosphere.

SUNSPOTS AND SPACE WEATHER A sunspot is a region of the Sun’s surface that is relatively cooler and darker than its surroundings Sunspots vary in size, locations, and number Changes about the locations of sunspots reveal information about the rotation of the Sun on its axis Space weather is the result of solar disturbances such as sunspots, which affect people and equipment in space and on Earth.

THE MOON- IMPACT CRATERS Impact craters are bowl-shaped holes in solid, rocky surfaces that are formed when large meteoroids, asteroids, or comets smash into the surface of a terrestrial planet, asteroid, or moon. The character of an impact crater depends on the size of the impacting object and the speed which it strikes the surface Rays of ejected materials radiate outward from an impact crater in all directions Many craters on Earth have been eroded by wind and water and destroyed by tectonics and volcanism.

SURFACE GRAVITY Gravitation is the force that attracts objects to each other. Surface gravity holds us to the Earth’s surface. Surface gravity depends on the mass and radius of the planet. Mass is the amount of matter in an object. Weight is the measure of the force of gravity on an object. An object with more mass has a stronger gravitational force pulling on it and therefore weighs more.

GRAVITY AND ORBITAL MOTION Any two objects, from the largest galaxies to the smallest particles, attract each other with a force called gravity. Gravity keeps planets in orbit around the Sun and governs all motion in the solar system Most objects in the solar system are in regular and predictable motion Unbalanced forces, including gravity, can change the speed and/or direction of an object’s motion.

GRAVITY AND ORBITAL MOTION

GRAVITY AND TIDES Tides are the periodic rise and fall of the sea level and other bodies of water The gravitational attraction between Moon and Earth (and Sun and Earth) contributes to the formation of tides Normally two high and two low tides occur each day The time at which high and low tides occur changes by about 50 minutes each day due to the Moon’s orbit around Earth.

GRAVITY AND TIDES

ASTEROIDS, COMETS, AND METEOROIDS Asteroids are rocky and metallic (nickel/iron) objects that orbit the Sun, but are too small to be considered planets. The majority of asteroids move between Jupiter and Mars in an area known as the “asteroid belt.” There are over 200 asteroids that regularly cross the path of Earth. These “Earth crossers” are usually about 1 km in diameter.

ASTEROIDS, COMETS, AND METEOROIDS Comets are relatively small solar system bodies made of ice, rock, and dust; each is in an independent elliptical orbit around the sun, often outside of the solar system. Ancient Greek scientists referred to comets as “hairy stars.” A comet is made of three parts: head, tail, and core / nucleus.

ASTEROIDS, COMETS, AND METEOROIDS Meteoroids are space matter too small to be called asteroids or comets. (They do not orbit the sun.) Meteors are streaks of light produced when meteoroids are illuminated as they fall into the Earth’s atmosphere (shooting stars)

ASTEROIDS, COMETS, AND METEOROIDS Meteorites are the actual rock pieces that hit the surface of the Earth. Meteorites that hit the Earth’s surface are moving at about 45 miles per second (162,000 miles per hour). Estimates suggest that more than 20 million meteors enter the Earth’s atmosphere daily – most break down before they get to the surface.

ASTEROIDS, COMETS, AND METEOROIDS

INNER PLANETS

OUTER PLANETS