Transcript January 2005 - Otterbein University

Welcome to
Starry Monday at Otterbein
Astronomy Lecture Series
-every first Monday of the monthJanuary 3, 2005
Dr. Uwe Trittmann
Today’s Topics
• Telescopes
• The Night Sky in January
Feedback!
• Please write down suggestions/your interests on the
note pads provided
• If you would like to hear from us, please leave your
email / address
• To learn more about astronomy and physics at
Otterbein, please visit
– http://www.otterbein.edu/dept/PHYS/weitkamp.asp (Obs.)
– http://www.otterbein.edu/dept/PHYS/ (Physics Dept.)
Telescopes
• From Galileo to Hubble
Telescopes
• Light
collectors
• Two types:
– Reflectors
(Mirrors)
– Refractors
(Lenses)
Refraction
• Light travels at different speeds in vacuum, air,
and other substances
• When light hits the material at an angle, part of it
slows down while the rest continues at the original
speed – results in a change of direction
– Different colors bend different amounts – prism,
rainbow
Refraction
• Lenses use refraction to focus light to a
single spot
Reflection
• Light that hits a mirror is
reflected at the same
angle it was incident
from
• Proper design of a mirror
(the shape of a parabola)
can focus all rays
incident on the mirror to
a single place
Reflecting Telescopes
Exploring our Telescopes
• Typical Questions:
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What type of telescope is it?
How big is it, i.e. what is its biggest optical device?
What is its focal length?
What is the focal length of the eyepiece?
What is its magnification?
Try to focus on an object. Describe the image.
If the telescope is on a mount:
• How many axes does the mount have?
• Does it have a motor?
• What is the type of mount?
Magnification
• Magnification of a telescope is determined
by the ratio of the focal length of the main
optical device F and the focal length of the
eyepiece f:
•
magnification= F / f
• The longer F the more magnification
• The shorter f the more magnification
Newtonian Telescope
• Long tubes (approx. focal length)
• Open at front
• Eyepiece on side
Schmidt-Cassegrain Telescope (CAT)
• Very compact & easy to use
• Closed (Corrector plate)
• Resonably priced
Refractor
• Two lenses -> inverted image
• Long tube (approx. focal length of
objective)
• Usually pretty expensive
Binoculars
• Erect image -> good for terrestrial viewing
• Prisms needed to produce erect image
• Typical specs: 8x60, means magnifies 8x
and objective lens is 60 mm in diameter
A good starting point
• A pair of binoculars and a star map will
keep you busy for a long time – anywhere!
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constellations
Planets
Moon
Orion nebula
Andromeda Galaxy
star clusters
…
The Night Sky in January
• The sun is very low in the sky -> long nights!
• Winter constellations (Orion, Gemini,
Taurus,…) contain many bright stars and objects
• The Earth is closest to the sun!
• Saturn is in Opposition (i.e. at its brightest)
What’s up in the night sky?
The Celestial Sphere
• An imaginary sphere
surrounding the earth,
on which we picture the
stars attached
• Axis through earth’s
north and south pole
goes through celestial
north and south pole
• Earth’s equator
Celestial equator
What’s up for you?
Observer
Coordinates
• Horizon – the
plane you stand on
• Zenith – the point
right above you
• Meridian – the
line from North to
Zenith to south
…depends where you are!
• Your local sky –
your view depends on your location on earth
Look
North in
Westerville
Look
North on
Hawai’i
Sun and Moon
January 3, 2005
Sun Rise
Sun Set
Actual Time
7:54 AM EST
5:19 PM EST
Civil Twilight
7:24 AM EST
5:49 PM EST
Nautical Twilight
6:50 AM EST
6:23 PM EST
Astronomical Twilight
6:17 AM EST
6:56 PM EST
12:11 AM EST
12:14 PM EST
Moon
Length of Day: 9h 25m, tomorrow will be 0m 53s longer
Length Of Visible Light: 10h 26m
Moon Phase: Waning Gibbous, 49% of moon illuminated
• From: wunderground.com
Moon Phases
• Today (Waning gibbous, 49%)
• 1 / 10 (New Moon)
• 1 / 17 (First Quarter Moon)
• 1 / 25 (Full Moon)
• 2 / 2 (Last Quarter Moon)
Today
at
Noon
Sun at
meridian,
i.e.
exactly
south
At
Sunset
10 PM
Typical
observing
hour, early
January
no Moon
Saturn!
Zenith
High in the
sky:
Perseus and
Auriga
with Plejades and
the Double
Cluster
NorthEast
Big Dipper
points to the
north pole
SouthWest
The Autumn
Constellations
• W of Cassiopeia
• Big Square of
Pegasus
• Andromeda
Galaxy
Andromeda
Galaxy
• “PR” Foto
• Actual look
Due
South
The Winter
Constellations
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Orion
Taurus
Canis Major
Gemini
Canis Minor
Saturn
• Day of opposition: January 13, 2005
• Distance at opposition:
8.094 A.U. or 748 million miles
• Apparent diameter: 20” or 1/90 that of the moon
• Actual diameter: 120,000 km or 10 Earths
Changing Ring Opening
2000
1999
1998
1997
1996
Titan – Saturn’s largest moon
• STRANGE TITAN: Get ready
for two of the strangest hours
in the history of space
exploration. That's how long it
will take the European Space
Agency's Huygens probe to
parachute to the surface of
Saturn's largest moon Titan
on January 14th. Huygens will
sample Titan's atmosphere,
photograph its bizarre terrain,
listen for alien sounds and,
possibly, splash down in a
liquid methane sea.
Comet Machholz
• Comet Machholz (C/2004
Q2) is approaching Earth
and gliding through the
constellation Taurus.
• It's easy to find. Go outside
and look south between 9
and 10 PM. To the unaided
eye, it looks like a faint and
fuzzy green star.
• Through a small telescope,
you can see the comet's
two tails.
Mark your Calendars!
• Next Starry Monday at Otterbein: February 7, 2005, 7 pm
(this is a Monday
• Web pages:
– http://www.otterbein.edu/dept/PHYS/weitkamp.asp (Obs.)
– http://www.otterbein.edu/dept/PHYS/ (Physics Dept.)
)
Famous Telescopes - Galileo
• Galileo’s first telescope was 3x magnifying
• his last one 32 x
Famous Telescopes -Newton
• First Reflector ever
• Built around 1670
• After this: gargantuan
Telescopes!
Famous Telescopes - Hevelius
Rooftop observatory of Johannes Hevelius (1670)
Famous Telescopes - Hevelius
60 inch ^
140 inch 
Famous Telescopes - Herschel
Herschel detected Uranus (1781)
Famous Telescopes – Lord Ross
• 72 inch Reflector
• built during potato famine in Ireland
• Largest Telescope until Mt Wilson
(1917)
Famous Telescopes – Yerkes
• Largest Refractor
Telescope ever
• 40 inch lens
• Built 1897
Famous Telescopes – Mt Palomar
• 5 Meter Telescope – Huge and heavy mirror
• On Mt. Palomar in California
Famous
Telescopes –
Hubble Space
Telescope
• In orbit around earth
• No limitations due
to earth’s
atmosphere
• Brilliant pictures
Famous Telescopes – Arecibo Radio
Telescope
• Located in
Puerto Rico
• 300m
diameter
• Receives
Radio waves
• Built 1963
• SETI
Famous People
Hubble in prime focus of
Mt Palomar.
Einstein visits Mt Wilson
Hubble detected the Expansion of the Universe
 Proof of Einstein’s General Relativity Theory
Largest Earth-Based Telescopes
• Keck I and II,
Mauna Kea,
Hawai’i
– 36  1.8 m
hexagonal mirrors;
equivalent to 10 m
– Above most of
atmosphere
(almost 14,000 ft
ASL)
– Operating since
1993
Visiting Mauna Kea