SMALLEST LARGEST UNIVERSE SOLAR SYSTEM STARS GALAXIES MILKY WAY TIME SPACE EVERYTHING SOLAR SYSTEM STARS GALAXIES PLANETS MILKY WAY SUN NORTH STAR OTHER CRAP

Thought Question: If you could see stars during the day, this is what the sky would look like at noon on a given day. The Sun is near the stars of the constellation Gemini. Near which constellation would you expect the Sun to be located at sunset? Leo Cancer Gemini Taurus Pisces Answer: FIRST DAY EXAMPLE QUESTION – 3 (10% correct; 90% after discussion)

Thought Question Which of the following describes when constellations are visible from San Diego (if it is dark enough and the clouds cooperate)? You could observe any constellation tonight at midnight. You could observe any constellation sometime during the night. You could observe any constellation on some night during the next year. Some constellations will never be visible from here. answer: D (80%) starter question for first lecture to test that they read?

CONSTELLATIONS: for orienting ourselves in the sky: NORTH STAR Astronomers have difficult problem – no laboratory … find in sky How many think they know which is the North Star? Constellations will have same pattern over your lifetime BUT whole sky moves around

Being a Good Astronomer ATMOSPHERE Complications in finding things: Earth is a sphere (people in different places see different stars) Earth rotates (stars continually move across sky) Earth orbits the Sun (stars don’t appear in same place from month to month) Some of our targets are moving too…

Being a Good Astronomer ATMOSPHERE HIGH ALTITUDE LOW ALTITUDE High in the sky is best because… the more atmosphere you have to look through: the more light is blocked the more the colors are affected EXPLAIN!! (as class intro); atmosphere is the enemy (though air is delicious to breathe); transparency demonstration?

Where in the Sky? To describe position in sky, need two coordinates: ZENITH To describe position in sky, need two coordinates: Altitude (ALT): angle above horizon 0º: horizon 90º: zenith Direction (DIR): angle clockwise from N measured around horizon 0º: N 180º: S 90º: E 270º: W NORTH STAR E N S W NORTH STAR BOARD DRAWING to label altitude, direction; give students time to take notes fist for a 10º increment talk about instruments for observing mini-projects E S N W

Being a Good Astronomer ATMOSPHERE Best telescopes usually scheduled months in advance: must be able to predict when an object will be up light from Sun, Moon should not interfere

Stars Move? leave as a mystery for now…

Thought Question In the past, several TV shows (NBC Nightly News, The Daily Show) had opening graphics which showed the Earth spinning the wrong way. If you were watching Earth from a stationary position out in space (as shown below), what direction does it spin? Left to right Right to left answer: A (80%)

Celestial Sphere Stars appear to move as if attached to a sphere rotating around Earth Celestial poles: above Earth’s N and S poles Celestial equator: directly above Earth’s equator

Earth Surface Coordinates NORTH POLE 90º N EQUATOR 0º blackboard drawing? SOUTH POLE 90º S

Celestial Coordinates NORTH CELESTIAL POLE NORTH CELESTIAL POLE RIGHT ASCENSION LINES CELESTIAL EQUATOR Earth lat., long. change slowly due to plate movements; star RA, DEC change very slowly due to motions DECLINATION LINES SOUTH CELESTIAL POLE SOUTH CELESTIAL POLE

Celestial Coordinates north celestial pole declination (DEC): like latitude on Earth north celestial pole: +90º celestial equator: 0º south celestial pole: -90º right ascension (RA): like longitude on Earth BUT… counted in hrs, increases toward east Earth lat., long. change slowly due to plate movements; star RA, DEC change very slowly due to motions http://astro.unl.edu/naap/motion2/animations/ce_hc.html

The Sky from San Diego circumpolar: stars that don’t rise or set for a person Most stars rise in east half of sky, and set in west half: LOOKING NORTH LOOKING SOUTH NORTH CELESTIAL POLE www.neave.com/planetarium/ http://astro.unl.edu/naap/motion2/animations/ce_hc.html - USE THIS ONE!! Starry night movies don’t show up too well  stars circle in 23h56m E S N W HORIZON

Thought Question If you watched the star pictured below from San Diego over several hours, what would happen? Its altitude and direction wouldn’t change. Its altitude would change, but direction wouldn’t. Its direction would change, but altitude wouldn’t. Both its direction and altitude would change. answer: D (20%) E N S W HORIZON

Using a Telescope A telescope pointing at one ALT and DIR doesn’t move BUT a star’s ALT and DIR both change during night Is there a better way? example: radar tracking of planes; artillery,spotlights are on alt-az mounts video links are to Starry Night movies