* 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.
* 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.
* 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).
* 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.
* 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.
* Includes: 1-Convection Zone 2-Radiative Zone 3-The Core
* 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.
* 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.
* 4.6 billion years ago, our solar system was formed from a cloud of hydrogen, helium, rock, ice, and other materials.
* Gravity began to pull together materials in a cloud.
* A rotating disk of gas, ice, and dust formed the cloud material was drawn toward the central mass.
* The disc became more dense, pressures increased, so then the center grew hot.
* Temperatures/pressure became so high that hydrogen atoms combined to form helium.
* This process is called nuclear fusion.
* The inner planets weak gravity + hot environment gave them dry, rocky bodies that were unable to hold on to light gases (hydrogen and helium).
* Far from the sun, ice combined with rocks and metal for a cooler environment.
* The outer planets were massive and gravity exerted a strong pull on hydrogen and helium.
Revolution- time to complete one orbit around the sun
planetesimals help the formation of the solar system by colliding and forming larger objects
the inner planets are rocky due to how close they are to the sun’s heat and radiation
scientists estimate the solar system’s age by measuring the distances of planets
the atmosphere is made up of 3 layers of plasma
the sun’s core is mostly made of plasma continuing hydrogen and helium
sudden magnetic energy release can cause a solar flare