Upload
kiya-inglett
View
215
Download
2
Tags:
Embed Size (px)
Citation preview
SMALLEST LARGEST
UNIVERSE
TIME
SPACE
EVERYTHING
SOLAR SYSTEM STARS GALAXIES
MILKY WAY
PLANETS
OTHER CRAP
SUN
NORTH STAR
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?
A. LeoB. CancerC. GeminiD. TaurusE. Pisces
Thought Question
Which of the following describes when constellations are visible from San Diego (if it is dark enough and the clouds cooperate)?
A. You could observe any constellation tonight at midnight.
B. You could observe any constellation sometime during the night.
C. You could observe any constellation on some night during the next year.
D. Some constellations will never be visible from here.
Being a Good Astronomer
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…
ATMOSPHERE
Being a Good Astronomer
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
ATMOSPHEREHIGH ALTITUDELOW
ALTITUDE
Where in the Sky?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
SN
E
W
N
E
W
S
NORTH STAR
ZENITH
Being a Good Astronomer
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
ATMOSPHERE
Thought QuestionIn 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?
A. Left to right
B. Right to left
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
Celestial Coordinates
SOUTH CELESTIAL POLE
NORTH CELESTIAL POLE
CELESTIAL EQUATOR
DECLINATION LINES
SOUTH CELESTIAL POLE
NORTH CELESTIAL POLERIGHT
ASCENSION LINES
Celestial Coordinates
declination (DEC): like latitude on Earthnorth celestial pole: +90ºcelestial equator: 0ºsouth celestial pole: -90º
right ascension (RA): like longitude on Earth
BUT… counted in hrs, increases toward east
north celestial pole
The Sky from San DiegoMost stars rise in east half of sky,
and set in west half:
NORTH CELESTIAL POLE
LOOKING SOUTH
N
W
S
E
HORIZON
circumpolar: stars that don’t rise or set for a person
LOOKING NORTH
stars circle in 23h56m
Thought QuestionIf you watched the star pictured below from San Diego over
several hours, what would happen?A. Its altitude and direction wouldn’t change.B. Its altitude would change, but direction wouldn’t.C. Its direction would change, but altitude wouldn’t.D. Both its direction and altitude would change.
HORIZON
N
E
W
S
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?