Transcript Star Gazing

Star Gazing
• Star Gazing techniques and tips: how to
get the most out of looking up at the stars
(powerpoint and notes on class website)
• Show 2 flashcards/notecards to me.
• Email me if you haven’t yet stating, “I found the
class website.” Details in the notes from last
Tuesday, Jan. 13
• If you haven’t given me a code to use for your
grades on the class website, see Raquel.
Sky Software
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Starry Night College ($30)
SkyX
Stellarium (free)
Celestia (free)
Google Earth and Google Sky
https://www.google.com/sky/ (free)
Sky Phone Apps (all free)
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Google Sky Map
Phases of the Moon
Sunrise Sunset
ISS Detector (International Space Station)
NASA
Lots of other star apps out there
Positions on the sky - Direction
• How can you find N, S, E, or W?
– Compass
– Phone/GPS/Car
– Map
– North Star = Polaris
Positions on the sky - Altitude
• Horizon – intersection of Earth and sky
• Zenith – point in sky directly overhead
– 90 degrees
– Halfway: 45 degrees
• Fist Method: Extended fist is ~10 degrees
Exercise (Right angle in classroom)
Exercise (Height of building from ground)
Star Charts
• Print Sky Map if you missed lecture:
• http://skymaps.com/articles/n1409.html
• Finding N, S, E, W
• Orienting the star chart
– If you face N, hold N down on the chart,
closest to you.
From Star Chart to Sky
• Note where constellation is on map
(direction and altitude)
• Use fist method to find it in sky
• Examples
– Cygnus
– Polaris
– Mars
Star Hopping
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Ursa Major to Ursa Minor (Polaris)
Ursa Major: arc to Arturus (in Bootes)
Cassiopeia: left V eats Polaris
Cassiopeia: right V points to Andromeda
(only galaxy visible to the naked eye); then
Andromeda curves to Great Square of
Pegasus
• Deneb (NE) to Altair (southern tip of
Summer Triangle) points to bottom left of
The Teapot handle
Greek Letters on star charts
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Brightest stars in that constellation
Alpha ( α )
Beta ( β )
Gamma (γ )
Delta ( δ )
• Example: Deneb in Cygnus is Alpha Cygni
Why is the TIME on the
star chart?
• Earth’s Rotation…
– Displays different constellations throughout
the night
• In the northern hemisphere, the stars
appear to rotate around Polaris, the North
Celestial Pole.
Polaris, the north star, with all of the stars moving
around it. The star trails are from the Earth’s rotation.
http://apod.nasa.gov/apod/ap091128.html
Why is the DATE on the
star chart?
• Earth’s Revolution...
– Displays different constellations throughout
the year
Planisphere
- North on front
- South on back
For more
instructions about
how to use your
planisphere:
http://astronomy.s
ierracollege.edu/C
ourses/Astronomy
02/Planisphere.ht
m
• 12 Constellations of the Zodiac seen throughout the year
because of Earth’s revolution.
• The zodiacal constellations are located along the Sun’s path on
Earth (Ecliptic).
• The Ecliptic is also the plane of Earth’s path around the Sun.
http://lifeng.lamost.org/courses/astrotoday/CHAISSON/AT301/HTML/AT30103.HTM
Apparent Visual Magnitude
• Hipparchus
– 1 (first magnitude)
bright to eye
– 2 (second magnitude) fainter
– …6 (sixth magnitude) faintest to eye
– 1st magnitude is 100 times brighter than the
6th magnitude
– Originally based on Polaris (app. mag. = 2)
– Now extended to negative numbers
– Example: Sirius, brightest star in the sky has
magnitude -1.4
Dark Adaptation
In dark, eye pupil enlarges to let in more light.
In sun, pupil shrinks to keep out light.
Exercise with dim lights
Dark Adaptation
• When star gazing, eye pupil needs to open
up (~15 minutes)
• Eyes have cones and rods
(photoreceptors)
– Cones see color & adapt to darkness quickly
– Rods take 10-30 minutes to adapt to darkness
• It shuts down quickly in response to white
light but not to red light.
• Therefore use red flashlights.
Dark Adaptation
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4.
Show red covered flashlights
Turn lights off and use curtains
Show colors displayed around the room
Color differentiation disappears after 10
minutes (color is from cones)
5. About 15 minutes in, rods take over; no
color and now see light trails (sparklers);
laser demo
Dark Adaptation Blind Spot
• Little dipper & Polaris example
http://www.optics4kids.org/getattachment/13cb7b00-117a-4e69-9d5d-35ad7d949199/OpticalIllusions.aspx
(draw Little Dipper constellation on whiteboard)
Eye Blind Spot
• Cross-dot demo of blind spot (draw on paper)
http://www.optics4kids.org/getattachment/13cb7b00-117a-4e69-9d5d35ad7d949199/Optical-Illusions.aspx
Sunset Part 1 Observation
• Jan. 20 to Feb. 12 to complete
• Take a picture of the sunset with 30o open
region to the right of the sun (spring sunset).
Use fist method (arm outstretched) to
measure 30o (3 fist lengths) to the right/north
of sunset now.
• Specific directions on website for what you
need to write down.
• Turn in the picture with details listed in the
calendar sunset observation file.
• Part 2: Apr. 2 to Apr. 28 to complete the 2nd
picture in EXACT SAME SPOT
Homework
• See today’s notes
• http://mctcteach.org/astronomy/
• Show 2 flashcards/notecards to me.
• Email me if you haven’t yet stating, “I
found the class website.” Details in the
notes from last Tuesday, Jan. 13
• If you haven’t given me a code to use for
your grades on the class website, see me.