
Hubble Space Telescope (HST) and Earth p.1
Instructor Prof. Vasken Hagopian Office 517 Keen (Physics) Building Office hours; Tu, Th 2:00 – 3:15 PM. Textbook: Astronomy; A Beginner’s Guide to the Universe, Fifth Edition by Chaisson and McMillan. Pub. Pearson – Prentice Hall. All class material is on the WEB at www.physics.fsu.edu/courses/ast1002H AST1002H Sections 4 and 5
The grade will based on three tests, each 20%, research report 15%, class participation and occaisional quizzes 10% and final exam 25%. If you do miss a test for a valid reason, it must be made up by an oral exam arranged promptly with your instructor. If you miss the final exam, again for a valid reason, you will receive a grade of I (Incomplete), only, if your total score at that time is e greater than 50 percentage points out of the total possible 75 percentage points. Otherwise your grade will be an F Grade
90 – 100 A 88 – 89 A- 86 – 87 B+ 80 – 85 B 78 – 79 B- 76 – 77 C+ 70 – 75 C 68 – 69 C- 66 – 67 D+ 60 - 65 D Below 60 F. Grade Scale
Speed of lightc = 300,000 km/sec = 3 × 108 m/s. Visible light, radio waves, ultraviolet, infrared, microwave, x-ray as well as gamma rays all travel at the speed of light. These are called the Electromagnetic (EM) Spectrum. All have the same speed c. Astronomical Unit (AU) = 1.5 ×1011 m = 1.5 ×108 km is the distance between the Sun and Earth. Light year (ly) = about 1 ×1016 m = 1 ×1013 km is the distance light travels in on year! Observation of an object one million light years away, means we are observing when the light left the object a million years ago, i.e. looking back in time. 1 ly = (365.25 days/year)×(24 hr/day)×(60 min/hr)×(60 sec/min)×(3 × 108 m/s) = 1 × 1016 m = 1 × 1013 km . Nearest star Proxima Century is about 4.2 ly distance from us. Our galaxy has about 1 ×1011stars and is average in size. We can only see about 6,000 stars with the naked eye. Has a massive 3 × 106Solar mass black hole in the center. Units of Distance
Age of universe about 14 billion years 1.4 × 1010 years Fig 1-1, p. 2
Solar System: About 40 AU in size. Sun: Over 99% of mass Planets 8 or 9! Moons, Asteroids, Comets Meteors, dwarf planets, etc. SUN Planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto(?). Fig 1-14, p.11
The sky is divided into 88 constellations. The brightest star in a constellation is α, next is β, then γ, etc The constellation pattern is as seen by us, as it ignores distance from us. Fig 1-7, p.6
Orion Constellation Bright red star is Betelgeuse
Cygnus Lyra Aquila Fig 1-10, p.7
Closest Star is Proxima Century 4.2 ly Away. p.13
Cone Nebula ground telescope Fig 1-3a, p.4
Cone nebula by HST Fig 1-3b, p.4
Crab nebula Fig 1-6a, p.6
Milky way and comet Haley Fig 1-13, p.13
Aries Taurus Gemini Cancer Leo Virgo Libra Scorpion Sagittarius Capricorn Aquarius Pisces Zodiac 12 constellations through which the Sun, Moon planets pass Fig 1-17, p. 18
Earth’s Orbital Motion 12 constellations Sun moves through during the year are called the zodiac; path is ecliptic
Coordinate Systems Constellations:A rough coordinate system of the Celestial Sphere. There are 88 constellations. Altitude: Angle above the horizon. Horizon -- 0º. Zenith: Straight up, -- 90º. Azimuth: Angle around the horizon. North = 0º; East = 90º; South = 180º; West = 270º. Latitude: Degrees north or south of the equator. North pole = +90º; Equator = 0º; South Pole = -90º. Tallahassee latitude = +30º. Longitude: The great circles that passes through the North Pole and South Pole. Measured in degrees from the circle that passes through Greenwich, England. Tallahassee longitude = 84ºW. Declination: The latitude fixed in the stars (Celestial latitude). North Pole = 90º; Celestial Equator = 0º; South Pole = -90º. Right Ascension:The longitude fixed in the stars. Units used are hours, minutes and seconds. The sky rotates one-hour unit per clock hour. 1 hour = 15º. Right ascension 0 hour is defined by the location of the Sun at Vernal equinox – about March 21, when the Sun is on the equator. Meridian: Imaginary line from North Pole to zenith to South Pole.
Celestial sphere Fig. 4-22, p.69
International time zones. Fig. 4-29, p.73
Zero degree longitude in Greenwich England Fig. 4-28, p.72
Earth’s Orbital Motion • Daily cycle, noon to noon, isdiurnal motion (Synodic)– solar day 24 hours. • Stars aren’t in quite the same place 24 hours later, though, due to Earth’s revolution around Sun; when they are, onesidereal dayhas passed. • Siderial day is 23 hr 56 min.
First day of Spring ~ March 21. Vernal equinox. Sun is on the equator. First day of Summer ~ June 22. Summer Solstice. Sun farthest north. First day of Fall ~ Sept 22. Autumnal equinox. Sun is on the equator. First day of Winter ~ Dec 22. Winter Solstice. Sun farthest south. Dates are approximate (~) due to leap years. Seasons
North star Polaris Fig. 4-20, p.68
Orbits of planets and Moon All revolutions in the same direction.
Today Polaris Vega in 12,000 years Precession – period about 26,000 years Fig. 4-21, p.68
Precession: rotation of Earth’s axis itself; makes one complete circle in about 26,000 years
The Moon p.13
Moon phases Fig. 4-2b, p.56
Moon sidereal period is 27.3 days. Moon synodic period (i.e. full Moon to full Moon is 29.5 days. Each day the Moon rises 50 min later. Fig. 4-5, p.57
Eclipses Fig. 4-7, p.58
The angular size of the Sun and Moon are about ½º. One arc sec angle is a dime at 2.5 km (1.5 mi). Fig. 4-10, p.60
Lunar eclipse, phase of Moon Full Fig. 4-9, p.59
Solar eclipse with diamond-ring effect Fig. 4-11, p.61
Total solar eclipse, phase of Moon New Fig. 4-12, p.61
Moon orbit is tipped 5º with respect to ecliptic Fig. 4-6a, p.58
E.3 Motion of the Moon Eclipse tracks, 2000 - 2020
Angular Measure • full circle contains 360° (degrees) • each degree contains 60′ (arc-minutes) • each arc-minute contains 60′′ (arc-seconds) • angular size of an object depends on actual size and distance away
E.4 The Measurement of Distance Triangulation: measure baseline and angles, can calculate distance
E.4 The Measurement of Distance Parallax: similar to triangulation, but look at apparent motion of object against distant background from two vantage points