“Stars die and reborn… They get so hot that the nuclei of the atoms fuse together deep within them to make the oxygen we breathe, the carbon in our muscles, the calcium in our bones, the iron in our blood… The cosmos is also within us. You, me, everyone. We are made of star stuff.” Neil DeGrasse Tyson

Astronomy is the study of the universe and the objects in it. The universe is all the matter and energy that exists everywhere. The universe includes: ä All stars and constellations, galaxies ä ä Meteorites and meteors ä Planets, moons and satellites ä ä Supernovas, pulsars and quasars ä Asteroids ä Plasma (free moving electrons and ions)

Star Constellations We see stars in the sky. ä ä A constellation is a group of stars that forms a shape or pattern. ä ä Constellations are used for calendars, keeping time, finding one’s direction on land and at sea. ä ä These stars appear to move from East to West across the celestial sphere. ä ä The stars appear to move across the sky in one night, but this is just an illusion due to Earth’s ROTATION.

Rotation The apparent daily motion of celestial objects is due to Earth’s rotation. Rotation is the turning of an object on its axis. Celestial objects are not actually moving from east to west across the sky, rather the earth is rotating under them.

Rotations

Revolution Revolution Revolution is the movement of one celestial object around another. The path along which an object travels during a revolution is called an orbit.

Earth’s revolution around the Sun makes the seasons. Earth’s revolution around the Sun makes the seasons.

Stars and Planets ä ä The solar system is made up of the Sun, and all the objects that travel around it. ä ä The planets are NONLUMINOUS - we see them because light reflects off them (they don’t glow). ä ä The sun and stars glow - they are called LUMINOUS

Observing Stars and Planets ä ä We can see Mercury, Venus, Mars, Jupiter, and Saturn without binoculars ä ä The brightest star we can see is Sirius. ä ä Our nearest star is the Sun.

The Difference between Planets and Stars ä ä Planets - o o Are near – in our solar system (also many now found around other stars) o o Are smaller than stars o o Reflect light from the sun o o Are usually cool or cold o o Are usually made of rocks or gases o o Have a steady light o o Wander slowly through constellations

The Difference between Planets and Stars (continued) ä ä Stars o o Are very far away, past our solar system o o Are larger than planets o o Give off their OWN light o o Are very hot o o Are made of high temperature gases o o Appear to twinkle o o Move as part of a constellation