Astronomy Study of objects in space such as the Sun, stars, planets, comets, gas, & galaxies. *Also, the Earth’s place in the universe. Universe = everything that exists

Astrology is NOT science !!! Disclaimer: Astrology is NOT science !!! There is currently no evidence that star positions affect human behavior or your future. Go ahead & read your horoscope but remember that it is just entertainment!

Geo-centric Helio-centric Earth-centered view of universe Sun-centered view of solar system C. Ptolomy 90-168 N. Copernicus 1473-1543 modern view of the solar system: “the Sun” is a star planets orbit the Sun

Galaxies = groups of billions of stars there are more than 100 billion galaxies they all have different shapes Spiral Elliptical Irregular

Universe Galaxies Cosmic Size Solar systems Stars Star clusters & Constellations Solar systems Stars Planets, moons Asteroids, meteors, meteorites, comets The “Big Dipper” constellation is a pattern made of 7 stars watch this! Powers of Ten Video

Apple in the Dark Imagine you are sitting at a table with a red apple in front of you. Your friend turns off all the lights. It is totally dark in the room. There are no windows in the room or crack around the door. No light can enter the room. Write the statement you believe best describes how you would see the apple in the dark & explain your answer in a short paragraph. You will not see the red apple, regardless of how long you are in the room. You will see the red apple after your eyes have had time to adjust to the darkness. You will see the apple after your eyes have had time to adjust to the darkness, but you will not see the red color. You will only see the shadow of the apple after your eyes have had time to adjust to the darkness. You will see only a faint outline of the apple after your eyes have had time to adjust to the darkness.

Light: Electromagnetic spectrum & Doppler Shift spectrum on: p. 484 & 678 Light: Electromagnetic spectrum & Doppler Shift

Spectrum: light separated into component wavelengths Learning from Light What is white light? What is a prism? Is there light we can’t see? What is ROY G. BIV? Spectrum: light separated into component wavelengths spectrum on: p. 484 & 678

Electromagnetic Energy energy that travels in waves spectrum on: p. 484 & 678

Draw your wave: Gamma Rays 1 cm X – Rays 2 cm Ultraviolet 3 cm Visible Light 4 cm Infrared 5 cm Microwaves 6 cm Radio Waves 7 cm spectrum on: p. 484 & 678

The Electromagnetic Spectrum

Earth’s Seasons = caused by the tilted axis (23.5o) Equinox = equal hours of daylight & darkness Solstice = longest day & shortest day Fall Sep. 21 SUN Dec. 21 Jun. 21 (shortest day) (longest day) Mar. 21 Spring

How we “see” the universe: this is a RADIO TELESCOPE we use this information to study galaxies

Types of spectra Sunlight, light bulbs Sunlight that has traveled through our atmosphere Hot gas

Doppler Effect wavelength changes if an object is moving toward or away from you pitch gets higher Whitney Houston !!! BASS !!! pitch gets lower

Doppler shifts from stars Doppler Effect Song by Astrocapella

The Expanding Universe 1929 – Edwin Hubble found that the universe is expanding Estimated distances, relative brightness, Doppler red shifts

Hubble’s Law: galaxies are moving away from us (red-shift) at a speed that is proportional to their distance the more distant the galaxy, the greater the velocity (moving away at faster speeds)

Big Bang Theory At one time, the universe was a hot, super dense ball smaller than an atom. About 13.7 billion years ago, a rapid expansion occurred sending material in all directions. This was the beginning of the universe. Eventually, matter cooled & condensed into galaxies, stars, & planets.

Support for the Big Bang Theory Red shifts Cosmic background radiation (CBR) Signals coming from every direction in space. Radio, microwave, infrared, & X-rays. Believed to be created by the big bang expansion. Video

Cosmic Background Radiation (CBR) The hypothesis that the universe has always been expanding (since the “Big Bang”) predicted (1948) that radiation produced from the first moment of expansion would permeate the universe. In 1965 this radiation was discovered In 2003 astronomers studying the CBR determined the universe is 13.7 billion years old

Incandescence: glowing from heat Blue = hottest Red=coolest

A cloud of space dust or gas. Nebula A cloud of space dust or gas.

Nebular Hypothesis cloud of mostly hydrogen & helium A. nebula A. B. Started rotating & collapsing toward center because of gravity forming an accretion disk , also the Sun forms C. rocky & metallic materials form as nebula cools D. collisions of particles created asteroid-sized objects (protoplanets or planetesmals) E. Sun = most dense object, nuclear fusion Rock / Terrestrial planets = more dense, heavy material, closer orbit Gas / Jovian planets = least dense, lighter material, farther orbit B. accretion disk C. cooling D. protoplanets E. solar system

Earth’s Motions Rotation Revolution spinning of Earth from west to east on an axis results in day / night Earth makes one rotation in 24 hours Revolution Earth moves around the sun every 365¼ days

Earth’s Motions Precession The change in direction of the northern axis North star is different Nutation Slight wobble, or change, in Earth’s axis from 23.5° Very slow movement due to the gravity of the moon

Earth’s Motions Winter – closest to the sun Summer – farthest from the sun

Lunar Eclipses Occurs during full moon phases Do not see the moon because the Earth blocks light Sun, Earth, moon in a line

Solar Eclipses Occurs when sun is blocked by the moon Sun, moon, Earth If the moon is partially blocking the sun, a partial solar eclipse will occur

Equatorial Bulge The Earth is not completely round There is a bulge at the equator because of rotation Video Link

Kepler’s Laws 1st Law: orbital paths are ellipses (ovals) Sun is at one focal point Animation of Laws

Kepler’s Laws 2nd Law: a planet sweeps out equal areas in equal times

Kepler’s Laws 3rd Law: T2 = d3 T= time of orbit d = distance (avg) from the sun

Barycenter The point between two objects where they balance each other The actual center of our solar system The sun orbits around this point Barycenter Video Music :)

Energy Nuclear Fission Nuclear Fusion The splitting of an atom to create energy Produced in nuclear reactors The fusion of two atoms to create energy Happens within stars

Cosmic Speed Limit Speed of light = 300,000 km/s Light-year = the distance light travels in one year (9,500,000,000,000 km) The 2nd nearest star is 4.3 light years away (Alpha Centauri = triple-star system)