THE EARTH IN SPACE

ESRT p. 15:
    "Luminosity and Temperature of Stars"

    "Solar System Data"

The Sun and the planets that revolve around it are the major bodies in the solar system.  Other members include comets, moons, and asteroids.  Earth's orbit is nearly circular. The shape of Earth, the other planets, and stars is nearly spherical. (ILS1.1c )

Most objects in the solar system are in regular and predictable motion. (PS1.1a)
 

        These motions explain such phenomena as the day, year, seasons, phases of the Moon, eclipses, and
         tides. 
 

        Gravity influences the motions of celestial objects.  The force of gravity between two objects in the
        Universe depends on their masses and the distance between them.

Gravity is the force that keeps planets in orbit around the Sun, and the Moon in orbit around the Earth. (ILS1.1d )

Most planets in the solar system have a regular and predictable motion.  These motions explain such phenomena as a day, a year, phase of the Moon, eclipses, tides, meteor showers, and comets. (ILS1.1d )

Nine planets move around the Sun in nearly circular orbits. (PS1.1b )

        The orbit of each planet is an ellipse with the Sun located at one of the foci.

        Earth is orbited by one Moon and many artificial satellites.

The apparent motions of the Sun, Moon, planets, and stars across the sky can be explained by Earth's rotation and revolution.  Earth's rotation causes the length of one day to be approximately 24 hours.  This rotation also causes the Sun and Moon to appear to rise along the eastern horizon and to set along the western horizon.  Earth's revolution around the Sun defines the length of the year as 365 1/4 days. (ILS1.1h )

The Sun's apparent path through the sky varies with latitude and season. (PS1.1h )

The tilt of Earth's axis of rotation and the revolution of Earth around the Sun cause seasons on Earth.  The length of daylight varies depending on latitude and season. (ILS1.1i )

The latitude/longitude coordinate system and our system of time are based on celestial observations. (ILS1.1f )

Earth’s coordinate system of latitude and longitude, with the equator and the prime meridian as reference lines, is based upon Earth's rotation and our observation of the Sun and stars. (PS1.1c )

Earth rotates on an imaginary axis at a rate of 15 degrees per hour.  To people on Earth, this turning of the planet makes it seem as though the Sun, Moon, and stars are moving around Earth once a day.  Rotation provides a basis for our system of local time. Meridians of longitude are the basis for time zones. (PS1.1d )

The Foucault pendulum and the Coriolis effect provide evidence of Earth's rotation. (PS1.1e )

Earth’s changing position with regard to the Sun and Moon has noticeable effects. (PS1.1f )

        Earth revolves around the Sun with its rotational axis tilted at 23.5 degrees to a line 
        perpendicular to the plane of its orbit, with the North Pole aligned with Polaris.

       During Earth's one-year period of revolution, the tilt of its axis results in changes in the 
       angle of incidence of the Sun's rays at a given latitude. These changes cause  variations
       in the heating of the surface.  This produces seasonal variation in weather.

Seasonal changes in the apparent positions of constellations provide evidence of Earth's revolution. (PS1.1g )

Approximately 70% of Earth's surface is covered by a relatively thin layer of water which responds to the gravitational attraction of the Moon and Sun with a daily cycle of high and low tides.(PS1.1i )

Earth systems have internal and external sources of energy, both of which create heat. (PS2.1a )

The Sun is a major source of energy for Earth. Other sources of energy include nuclear and geothermal. (ILS4.1a)

Insolation (incoming solar radiation) heats Earth's surface and atmosphere unequally due to variations in: intensity, characteristics of surface materials, and duration. (PS2.2a )

 
The transfer of heat energy within the atmosphere, hydrosphere, and surface occurs as a result of radiation, convection, and conduction. (PS2.2b)

    Heating of Earth's surface and atmosphere by the Sun drives convection with the atmosphere and oceans.

Earth’s Sun is an average-sized star.  The Sun is more than a million times greater in volume than Earth. (ILS1.1a )

Other stars are like the Sun but are so far away that they look like points of light.  Distances between stars are vast compared to distances within our solar system. (ILS1.1b )

Moons are seen by reflected light. Our Moon orbits Earth, while Earth orbits the Sun. The Moon's phases as observed from Earth are the result of seeing different portions of the lighted area of the Moon's surface. The phases repeat in a cyclic pattern in about one month. (ILS1.1g )

The Universe is vast and estimated to be over 10 billion years old.  The current theory is that the Universe was created from an explosion called the Big Bang. Evidence for this theory includes:

cosmic background radiation

a red-shift (Doppler effect) in light from very distant galaxies (PS1.2a )

Stars form when gravity causes clouds of molecules to contract until nuclear fusion of light elements into heavier elements occurs.  Fusion releases great amounts of energy over millions of years. (PS1.2b )
        The stars differ from each other in size, temperature, and age.
        Our Sun is a medium-sized star within a spiral galaxy known as the Milky Way.
        Our galaxy contains billions of stars, and the Universe contains billions of galaxies.

Our solar system formed about 5 billion years ago from a giant cloud of gas and debris.  Gravity caused Earth and the other planets to become layered according to density differences in their materials. (PS1.2c)
        The characteristics of the planets of the solar system are affected by each planet's location in
        relationships to the Sun.
 

  Terrestrial planets are small, rocky, and dense.  The Jovian planets are large, gaseous, and of low density.

Asteroids, comets, and meteors are components of our solar system. (PS1.2d )
         Impact events have been correlated with mass extinction and global climate change.
         Impact craters can be identified in Earth's crust.

Earth’s early atmosphere formed as a result of the outgassing of water vapor, carbon dioxide, nitrogen, and lesser amounts of other gases from its interior. (PS1.2e )

Earth’s oceans formed as a result of precipitation over millions of years.  The presence of an early ocean is indicated by sedimentary rocks of marine origin dating back about 4 billion years. (PS1.2f )

Earth has continuously been recycling water since the outgassing of water early in its history. This constant recirculation of water at and near Earth's surface is described as the hydrologic (water) cycle. (PS1.2g )

The evolution of life caused dramatic changes in the composition of earth's atmosphere.  Free oxygen did not form in the atmosphere until oxygen-producing organisms evolved. (PS1.2h )