Solar System Objects

Understanding the Solar System

* Solar system - consists of the sun, planets, their moons, and a variety of smaller objects.

* The sun is at the center of the solar system, with other objects orbiting around it.

* The force of gravity holds the objects in their orbit around it.

Distances in the Solar System

* Astronomical unit (AU) - one AU is the average distance measured from the center of the sun to the center of Earth.

* The entire solar system extends more than 100,000 AU.

Comparing the Sun and Planets

* Sun - a gaseous body much larger than anything else in our solar system.

* The sun is a mid-sized star expected to burn for another 5 billion years.

* Planet - is round; orbits the sun; has cleared its orbit of other objects.

* 4 inner planets, closer to the sun, small, made mostly of rock and metal.

* 4 outer planets, farther from the sun, very large; made mostly of gas or liquid.

* Rotate - the time it takes for one day (spin).

Smaller Solar System Objects

* Dwarf planet - an object that orbits the sun, has enough gravity to be spherical, has not cleared its orbit (pluto).

* Moon - a natural satellite that orbits a planet.

* The force of gravity between a planet and its moon keeps the moon in its orbit.

* Asteroids - small, mostly rocky bodies, found in an area between the orbits of mars and jupiter.

* Meteoroids - chunks of rock or dust smaller than asteroids.

* Meteor - a streak of light made when a meteoroid's friction creates heat.

* Meteorite - a meteoroid that passes through the atmosphere and has hit Earth's surface.

* Comets - loose balls of ice and rock, have very long and narrow orbits.

* Develop tails as they orbit the sun.

Structure of the Sun

* No solid surface; completely gaseous.

* Its mass is hydrogen and helium.

* The hydrogen and helium are in the form of plasma, a fourth state of matter.

* Plasma - very hot fluid-like gas consisting of electrically charged particles.

The Sun's Interior

* Includes: 1-Convection Zone 2-Radiative Zone 3-The Core

The Sun's Atmosphere

* It extends far into space.

* Made of hydrogen and helium.

* 3 main layers: photosphere, chromosphere, and the corona.

* Photosphere - inner layer of the atmosphere.

* Chromosphere - middle layer.

* Corona - outer layer, looks like a white halo around the sun.

Features of the Sun

* The most visible features are called sunspots, prominences, and solar flares.

* Sunspots - dark areas on the sun's surface.

sunspots are Areas of plasma that are cooler than the plasma around them.

* Cooler plasma gives off less light.

* Changing positions of sunspots indicates that the sun rotates.

* Prominences - huge loops of plasma that are polarized.

* Solar flares - loops in sunspot regions connect, releasing large amounts of magnetic energy; this energy heats plasma millions of degrees causing it to erupt into space.

* Eruptions are called solar flares.

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