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Welcome to. Starry Monday at Otterbein. Astronomy Lecture Series -every first Monday of the month- January 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
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Welcome to Starry Monday at Otterbein Astronomy Lecture Series -every first Monday of the month- January 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
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
Sun and Moon • 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
10 PM Typical observing hour, early January • no Moon • Saturn!
Zenith High in the sky: Perseus and Auriga 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 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 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