Starry Monday at Otterbein

1. Welcome to Starry Monday at Otterbein Astronomy Lecture Series -every first Monday of the month- October 6, 2008 Dr. Uwe Trittmann

2. Today’s Topics • Practical Astronomy –Star maps and such • The Night Sky in October

3. 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.)

4. 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

5. 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

6. …depends where you are! • Your local sky – your view depends on your location on earth

7. Look North in Westerville

8. Look North on Hawai’i

9. SkyGazer • A computer program that simulates the vision of the sky during day and night Things to observe: • Position on Earth: observe how the view of sky changes as you move E,W, N,S • Note the distribution of sunlight on Earth! • Rotation is around Polaris which is not in zenith

10. Star Maps • … are a 2D rendering of a 3D situation  They can’t be perfect! • You are looking at the inside of a sphere • East and West are reversed

11. On the Web • http://www.stargazing.net/David/constel/skymaps/novlines.html • http://www.google.com/sky/ • http://www.kidscosmos.org/kid-stuff/star-maps.html

12. Star Maps 40º 90º Celestial North Pole – everything turns around this point Zenith – the point right above you & the middle of the map

13. Daily Rising and Setting • Due to the rotation of the Earth around its axis • Period of rotation: 1 siderial day= 23h56m4.1s • 1 solar day (Noon to Noon) =24h • Stars rotate around the North Star – Polaris

14. That’s what you’d actually see! Confusing?

15. Experts’ view • Learn to identify crucial constellations • Find your way around the night sky

16. Hands On! • Dial in the night sky as we will see it NOW! • Advance time • Advance date

17. How bright are Stars? -The Magnitude Scale • The magnitude is a measure of the apparent brightness • Logarithmic scale • Notation: 1m.4 (smaller brighter) • Originally six groupings • 1st magnitude the brightest • 6th magnitude the dimmest • The absolute magnitude is the apparent magnitude a star would have at a distance of 33 ly: 2M.8

18. When can I see a star/constellation? • When the Sun is not in the constellation! • As Earth moves around the Sun, the Sun seems to move around the ecliptic: from Aries to Taurus, Gemini, etc. • As the Earth rotates, stars rise in the East • Wait a while and “your” star will rise • Bummer: if you have to wait too long, the Sun will rise, too, and outshine your star.

19. Sun’s Apparent Path As Earth moves around the Sun, the Sun appears “in front” of the constellations of the ecliptic (Zodiac)

20. 3D view Vernal equinox:Ecliptic intersects with celestial equator

21. When can I see the Moon? • Depends on its position relative to Sun, i.e. its phase • New Moon: same as Sun • Full Moon: opposite of Sun

22. When can I see the Planets? • The move slowly around the ecliptic • Look up in which constellation they appear • Identify them as “the extra star”

23. Motion of Sun, Moon and other Planets • All major bodies in the Solar System move around ecliptic • Slow drift (from W to E) against the background of stars

24. Night Sky of the Season • As a crude way of finding visible constellations, one divides them into Summer, Autumn, Winter and Spring constellations • Some constellations are ALWAYS visible – the circumpolar ones that are close enough to the celestial pole

25. The Night Sky in October • The sun is past autumn equinox -> longer nights! • Autumn constellations are coming up: Cassiopeia, Pegasus, Perseus, Andromeda, Pisces  lots of open star clusters! • Jupiter is visible all night

26. Moon Phases • Today (Waning Gibbous, 70%) • 10 / 7 (First Quarter Moon) • 10/ 14 (Full Moon) • 10 / 21 (Last Quarter Moon) • 10 / 28 (New Moon)

27. Today at Noon • Sun at meridian, i.e. exactly south

28. 10 PM Typical observing hour, early October • Uranus • Neptune Moon Jupiter

29. South-West High in the sky: The summer triangle

30. Due North • Big Dipper points to the north pole

31. High up – the Autumn Constellations • W of Cassiopeia • Big Square of Pegasus • Andromeda Galaxy

32. Andromeda Galaxy • “PR” Foto • Actual look

33. East Perseus and Auriga with Plejades and the Double Cluster

34. Greek Mytho-logy in the Sky

35. South -2006 • Planets • Uranus • Neptune • Zodiac: • Capricorn • Aquarius

36. South –2007 • Planets • Uranus • Neptune • Zodiac: • Capricorn • Aquarius

37. South –2008 • Planets • Uranus • Neptune • Zodiac: • Capricorn • Aquarius

38. Mark your Calendars! • Next Starry Monday: November 3, 2008, 7 pm (this is a Monday ) • Observing at Prairie Oaks Metro Park: • Friday, October 3, 7:45 pm • Friday, January 30, 7:00 pm • Web pages: • http://www.otterbein.edu/dept/PHYS/weitkamp.asp (Obs.) • http://www.otterbein.edu/dept/PHYS/ (Physics Dept.)

39. Mark your Calendars II • Physics Coffee is every Wednesday, 3:30 pm • Open to the public, everyone welcome! • Location: across the hall, Science 256 • Free coffee, cookies, etc.

40. Solar vs Siderial Day • Earth rotates in 23h56m • also rotates around sun  needs 4 min. to “catch up” • Consequence: stars rise 4 minutes earlier each night • after 1/2 year completely different sky at night!