Starry Monday at Otterbein

Astronomy Lecture Series-every first Monday of the month-

January 3, 2005

Dr. Uwe Trittmann

Welcome to

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:– 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!– 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

• From: wunderground.com

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

Moon 12:11 AM EST 12:14 PM EST

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

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 andAuriga

with Plejades and the Double

Cluster

North-East

• Big Dipper points to the north pole

South-West

The Autumn

Constellations

• W of Cassiopeia

• Big Square of Pegasus

• Andromeda Galaxy

Andromeda Galaxy

• “PR” Foto

• Actual look

Due South

• The Winter Constellations– 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

1998

1997

1996

2000

1999

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 Einstein visits Mt Wilson Mt Palomar.

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