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contact Dr. Doyle at rdoyle@frostburg.edu
Frostburg State Planetarium
presents
Spring 2015 Sky Sights for
Middle School & Intermediates
by Dr. Bob Doyle
Next Edition: July 2015
Big Topics Treated
• Horizon, Finding directions, Sunrise/Sunset
• How Day Sky Works, Twilight AM & PM
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Moon basics, It’s Origin Why has varying shapes?
Bright points seen at night? Easy Spring Planets
Best Stars & Groups Seen on Spring Evenings
3 Built in Mini Quizzes with answers supplied
Spring ‘15 Moon Schedule & Star diagrams
Spring Talk Show Schedule & related info
Horizon & Directions
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When looking at sky, we may view ½ of universe!
Horizon surrounds us, the sky/ground boundary
At top of sky is zenith, 90 degrees from horizon
From North rightward, East, then South and West.
Sun rises in East, face sunrise, left is North
Midday shadow N (1pm in April, May & June)
Sun sets nearly in West, face sunset, right is North
Can use Big Dipper’s pointers to find N. Star
Sunrise & Sunsets?
• Earth’s daily rotation makes it look as if sun rises
each morning & sets each afternoon
• Time of sunrise, sunset varies thru year
• Earliest sunrise & latest sunset in late June
• Latest sunrise & earliest sunset in late Dec.
• Longest days when sun highest, farthest N
• Shortest days when sun lowest, farthest S
• Change in sunrise/sunset reduced closer to equator
• Change in sunrise/sunset increased near poles
Let’s review these ideas
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What point in sky is farthest from horizon?
Is it Celestial Pole? Zenith? Nadir?
Which direction recipe WON’T work?
S= Moss side of tree N = Shadow in mid day?
Place where biggest changes with seasons?
Polar Regions? Mid Latitudes? Equator?
Write down your answers for these questions.
Answers: Zenith, Mid day shadow, Polar regions
Interesting facts about day sky
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Noon sun 400,000 x brighter than full moon
Day Sky max. polarization 90 deg. from sun
Maximum sunlight energy in early summer
Sun peaks around 1 pm when Daylight time
Minimum sunlight energy in late Dec.
To find North, face where sun goes down
and extend your right arm out, points North.
Twilight or Dusk?
• When sun disappears from our view, the air
overhead is still ‘seeing’ sun and glowing.
• Sun 6 degr. below horizon, turn on lights
• Sun 18 degr. below horizon, sky darkest
• To see most stars, sun must be 12 degr. below hor.
• Arctic Circle cities no darkness in June & July
• Equatorial places have shortest twilights
• Our twilights last about 90 min. at dusk & dawn
What about Moon?
• Our moon is 2160 miles across, ¼ Earth’s width
• Moon ¼ as big as Earth; if Earth a regular globe
(1 ft.wide), moon is a tennis ball.
• If Earth-moon distance about 30 x Earth’s width.
• As Earth, Moon lit by sun with day & night halves
• As Moon orbits Earth, see varying part of day side
• After line up with sun, moon waxes (grows) 14 d
• After full moon, moon wanes (shrinks) 14 days
• Moon phase cycle 29.5 dy, approx. month length
Just a little bit more about Moon
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Moon rocks reveal moon matter from Earth!
Moon due to planets colliding, debris hurled
Moon formed from ring of orbiting debris
Early moon closer, much stronger tides
Moon slowly spiraling out, lengthen our day
Earth has 1st natural moon from sun, 6th
largest moon in solar system
Spring 2015 Moon Schedule
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Early April: Full moon 4/4, slow evening exit
Mid April: Evening crescent after 4/19
Late April : 1/2 full evening moon on 4/25
Early May: Full moon 5/3, slow evening exit
Mid May : Evening crescent after 5/21
Late May: ½ full evening moon on 5/25
Early June: Full moon 6/2, slow evening exit
Mid June: Evening crescent after 6/19
Late June: ½ full evening moon on 6/24
Another review of ideas..
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As you face sunset, what points North?
Back of Head? Right arm (out)? Left ear?
If Earth 1 ft. wide, how far away is moon?
Is it 10 feet? 30 feet? 100 feet? 300 feet?
How long does moon ‘grow’ or ‘shrink’?
Is it A week? A half month? A month?
Write down your answers to above 3 questions.
Answers: Right arm (out), 30 feet, A half month
Bright points we see at night?
• Even the nearest planets appear as * (points) as we
see them with our eyes; for even these objects far
away Venus at closest 100x farther than our moon
• To tell a planet from a star, all night stars twinkle
and planets usually shine steady.
• Also satellites (especially Space Station) shine
steadily as creep eastward across sky
• Night stars are distant suns, really, really far away
compared to our planet neighbors.
• If Earth penny size, moon 22” away, sun 730 ft.
away (6.3 ft. wide), nearest star is 37,000 mi.away
Easy Spring 2015 Planets
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Brilliant Venus is in the western twilight
Crescent Moon & Venus close 4/22, 5/21, 6/20
Bright planet Jupiter in southwest, Venus to right
Moon & Jupiter close on 4/25, 5/23, 6/21
Venus and Jupiter very close on 6/30 in W. dusk
Saturn creeps into evening sky, closest on 5/22
Mercury below Venus, late Apr. & early May
Spring Stars & Groups
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Evening: Big Dipper upside down, pointers to N.*
Same Dipper * point right to sickle of Leo
Arc of Dipper’s handle arc to golden “Arcturus”
Low in SE is Scorpius, it’s stars forming ‘J’
In SE is the Summer Triangle, peaked by * Vega
Bright golden star Capella seen briefly low in NW
Big Dipper & N. Star in Spring
Big Dipper
North Star
Southern sky in Spring ‘14
Arcturus
Sickle of Leo
Spica
Regulus
Let’s review once more…
• Planet NOT prominent in Even.Spring skies’15?
Venus? Mars? Jupiter? Saturn?
• When closest to us, neighbor planet is invisible?
• Is it Moon? Mars? Jupiter? Venus?
• Big Dipper’s handle arcs to what bright star?
• North Star Sirius Capella Arcturus
• Write down your answers
• Answers: Mars Venus Arcturus
Send any questions to….
• Bob Doyle email rdoyle@frostburg.edu