Download
introduction to the night sky n.
Skip this Video
Loading SlideShow in 5 Seconds..
Introduction to the Night Sky PowerPoint Presentation
Download Presentation
Introduction to the Night Sky

Introduction to the Night Sky

66 Vues Download Presentation
Télécharger la présentation

Introduction to the Night Sky

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Ohio University - Lancaster Campus slide 1 of 21Spring 2009 PSC 100 Introduction to the Night Sky The Orion NebulaCredit: NASA, ESA, STScI The Eagle Nebula RegionCredit: NOAO/AURA/NSF

  2. Ohio University - Lancaster Campus slide 2 of 21Spring 2009 PSC 100 This evening, we are going to investigate: • sky landmarks and the celestial sphere • coordinate systems • how to use a planisphere • how to use a constellation chart

  3. Ohio University - Lancaster Campus slide 3 of 21Spring 2009 PSC 100 The sky looks like a bowl overhead. • This is the celestial sphere. • Landmarks are the horizon and the zenith (point directly over your head.)

  4. Ohio University - Lancaster Campus slide 4 of 21Spring 2009 PSC 100 Credit: astronomynotes.com

  5. Ohio University - Lancaster Campus slide 5 of 21Spring 2009 PSC 100 • We use the compass points (cardinal points) for direction. • Starting at 0o north and turning clockwise, the angle around the horizon is the azimuth. • East is 90o, South 180o, West 270o • The angle above the horizon is the altitude. • What is the altitude of the zenith?

  6. Ohio University - Lancaster Campus slide 6 of 21Spring 2009 PSC 100 • An imaginary line runs from due north, overhead through the zenith, to due south. • It splits the sky into an eastern (a.m.) half, and a western (p.m.) half. • What do “a.m.” and “p.m.” stand for? • What time is it, when the sun is directly on the meridian?

  7. Ohio University - Lancaster Campus slide 7 of 21Spring 2009 PSC 100 • This first coordinate system (altitude-azimuth or alt-az for short) is the most familiar, but the least functional. Why? • A couple other sky landmarks… • The sky seems to turn about a point in the sky near the north star. • The north celestial pole.

  8. Ohio University - Lancaster Campus slide 8 of 21Spring 2009 PSC 100 • The altitude of the north celestial pole is the same as your latitude above the equator. • What is the altitude of the north celestial pole here in Lancaster?

  9. Ohio University - Lancaster Campus slide 9 of 21Spring 2009 PSC 100

  10. Ohio University - Lancaster Campus slide 10 of 21 Spring 2009 PSC 100 • We can also project the earth’s equator into the sky - the celestial equator. • If the north celestial pole is 40o above the horizon here in Lancaster, what is the altitude of the celestial equator above the southern horizon? • Stars rise and set at this same angle with the horizon.

  11. Ohio University - Lancaster Campus slide 11 of 21 Spring 2009 PSC 100 • Where do you think you’d be on the earth’s surface if… • the north celestial pole is at the zenith? • the north celestial pole is on the horizon and the celestial equator runs across the zenith?

  12. Ohio University - Lancaster Campus slide 12 of 21 Spring 2009 PSC 100 • We now have a more useful coordinate system… • based on earth’s longitude (angle around earth’s equator, rather than the horizon) • based on earth’s latitude (angle up or down from the equator, rather than the horizon) • only one problem. What is it?

  13. Ohio University - Lancaster Campus slide 13 of 21 Spring 2009 PSC 100 • Solution? Let the longitude rotate along with the sky. • Instead of placing 0o longitude above Greenwich, England, we choose to place it at a fixed point in the sky - the point of the spring equinox in the constellation Pegasus.

  14. Ohio University - Lancaster Campus slide 14 of 21 Spring 2009 PSC 100 • To avoid confusion, we call celestial longitude right ascension. • Rather than give RA in degrees, we divide it into 24 hours (with each hour divided into 60 minutes and minutes into 60 seconds.) • Why would we do this?

  15. Ohio University - Lancaster Campus slide 15 of 21Spring 2009 PSC 100 • Celestial latitude is called declination. • We do measure this angle in degrees, minutes, and seconds, of arc. • What is the declination of the north celestial pole? The south celestial pole? The celestial equator?

  16. Ohio University - Lancaster Campus slide 16 of 21 Spring 2009 PSC 100 • Do the sun and planets move through the sky along the celestial equator?

  17. Ohio University - Lancaster Campus slide 17 of 21 Spring 2009 PSC 100 Credit: astronomynotes.com

  18. Ohio University - Lancaster Campus slide 18 of 21 Spring 2009 PSC 100 • The path of the sun and planets through the sky is the ecliptic. • The ecliptic is really the earth’s orbit projected into space. • The ecliptic intersects the celestial equator at the points of the spring and fall equinoxes. • What is the angle between the celestial equator and the ecliptic? Why?

  19. Ohio University - Lancaster Campus slide 19 of 21 Spring 2009 PSC 100 • You may know the ecliptic, and the constellations along it, better as the zodiac. • How many zodiac constellations are there? • Capricornus, Aquarius, Pisces (Fall) • Aries, Taurus, Gemini (Winter) • Cancer, Leo, Virgo (Spring) • Libra, Scorpius, Sagittarius (Summer) • and…Ophiuchus? (Summer also)

  20. Ohio University - Lancaster Campus slide 20 of 21 Spring 2009 PSC 100 Credit: www.lpi.usra.edu

  21. Ohio University - Lancaster Campus slide 21 of 21Spring 2009 PSC 100 • Next, we’re going to investigate 2 tools that will be useful in learning your way around the night sky • a star wheel or planisphere • a constellation chart

  22. Credit: freegeographytools.com