INTRODUCTION

 

 

TO

 

 

ASTRONOMY

 

 

 

 

 

 

 

 

 

INSTRUCTOR: Dr. MAHMOUD KHALILI

 

 

 

 

 

 

TEXT BOOK: Astronomy

 

A Beginner Guide to the Universe, Second Edition:

 By

 Chaisson & Mc Millan

 

 

 

 


                1: Project                        10 Point

 

                2: Quiz                             20 Point

 

Grade     3: Midterm Exam           35 Point

 

                4: Final Exam                 35 Point

 

                5: Attendance                 10 Point

 


                      Total          110 Point

 

 

Final Letter Grade:

 

                 Point                      Grade

                85-110                        A

                75- 84                         B

                60- 74                         C

                50  59                         D

                Less 50                       F

 

 

 

 

 

 

 

 

 

 

 


                      1: Introduction

 

                      2: Biography of Person

 

   Project          3: Scientific Contribution

                              (Any Discovery, Invention, Development.   )

 

                      4: Conclusion

 

                      5: Reference

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


OBJECTIVE OF PROLOGUE

 

 

1: System of Measurement

 

2: Scientific Notation

 

3: Concept of the Celestial Sphere

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

System of Measurement

 


Quantity                SI*                  C g S                 British System

 


Length ( L )               meter ( m )     centimeter (cm)             foot ( ft )

 


Mass( M )          Kilogram ( Kg )         gram ( gr )             slug

 


time ( t )                     second                   second                   second

 


Weight ( W )         Newton ( N )          dyn                     pound ( Ib )

 


Area ( A )              square meter square centimeter     square foot

                                  ( m2 )                      ( cm2 )                ( ft2 )

 


Volume( V )           cubic meter        cubic centimeter          cubic foot

                                  (m3 )                       (cm3 )                     (ft3 )

 


Speed( v )                  ( m / s )               ( cm / s )             ( ft / s )

 


Acceleration(a)     ( m / s2 )                 ( cm / s2 )                   ( ft / s2 )

 


Force( F )              Newton(N)                dyn                 pound( Ib )

 

 

 


SI* : System International( Metric System)

 

Conversion Factors:

 

1 m = 100 cm                                       1 mile = 1.609 Km

1 m = 3.28 ft                                        1 mile = 5280 ft

1 Kilometer = 1000 meter                       1 ft = 0.3.5 m

1 Kg 1000 gr = 2.2 Ib                              1 Ib = 0.455 Kg = 455 gr

1 Angstrom ( A0 ) = 10-10 m                 1 ft = 12 inch

1 nanometer ( nm ) = 10-9 m                1 inch = 2.54 cm

1 micron ( µm ) = 10-6 m

 

 

 

 

 

 

 

SCIENTIFIC NOTATION:

 

 

                 0.1  =  1 x 10-1                                                  1  =  1 x 100

 

                0.01  =  1 x 10-2                                               10  =  1 x 101 

 

               0.001  =  1 x 10-3                                            100  =  1 x 102

 

             0.0001  =  1 x 10-4                                           1,000  =  1 x 103

 

           0.00001  =  1 x 10-5                                         1,0000  =  1 x 104

 

         0.000001  =  1 x 10-6                                    1,000,000  =  1 x 106

                                                                            (million)

            0.0231  =  2.31 x 10-2                          1,000,000,000  =  1 x 109

                                                                               (billion)

 

 0.00000936815  =  9.37 x 10-6                 1000,000,000,000  =  1 x 1012

                                                                            (trillion)

 

                                                                                    6400  =  6.40 x 103

 

                                                                            2453700  =  2.45 x 106

 

 

 

 

 

 

 

 

 

ASTRONOMY: The scientific study of the universe beyond the Earth, especially the observation, calculation, and theoretical interpretation of the positions, dimensions, distribution, motion, composition, and evolution of celestial bodies and phenomena.

UNIVERSE: The totality of all space, time, matter and energy.

EARTH: Earth is an ordinary rocky planet orbiting an average star called Sun, one star near the edge of huge collection of stars called the Milky Way Galaxy.

     The age of Earth is about five to six billion years ( 5 x109 years)

 

SPEED OF LIGHT : 300,000 kilometers per second

                                          ( 186,000 miles per second)

LIGHT YEAR: The distance light travels in a year, at the rate of 300,000 kilometers per second; one light-year is equivalent to 9.46 x 1012 kilometers or 5.88x1012 miles.(About 6 trillion miles).

CONSTELLATIONS. A human grouping of stars in the night sky into a recognizable patterns are called constellations, from Latin words meaning together and stars. Today 88 constellations are recognized by astronomers. Orion, Canis Minor, Canis Major, Capricorn, Libra are some of famous constellations.

In a clear night between sunset and sunrise, we can see about 3000 stars on sky.

 

CELESTIAL SPHERE: An imaginary sphere surrounding the Earth, to which all objects in the sky were once considered to be attached.

NORTH CELESTIAL POLE: The point where the Earth’s axis intersects the celestial sphere is known as the north celestial pole, and it is directly above the Earth’s North pole.

SOUTH CELESTIAL POLE: The point where the Earth’s axis intersects the southern celestial sphere is known as the south celestial pole, and it is directly above the Earth’s south pole.

CELESTIAL EQUATOR: The projection of the Earth’s equator onto the celestial sphere.

 

PARALLAX: The apparent motion of a relatively close object with respect to a more distant background as the location of the observer changes. The amount of parallax is inversely proportional to the object distance.

 

                                                                              A

 


                                                                        a

 

AH = Distance to the object

 

BC = Base ( Diameter of Object)

a = Angular Diameter

 

 

                                                      B                    H                    C

 

 


               Diameter of object                   Angular Diameter( In degree)

               2 p x Distance                                                360

 

 

 

                                                                            BC                    Base

 PARALLAX (a Radian ) = tg ( a Degree ) =   ---------    =   --------------

                                                                            AB                  Distance

 

CONVERSION BETWEEN DEGREE AND RADIAN

 

 

 


              D                 R                                                    360 Degree

                         =                                                               or

            360               2 p                                                    2 p Radian

 

             Where  p = 3.14

              1o  = 60’ =  3600’’               1’ = 60’’

 

 

 

 

 

 

 

OBJECTIVE OF CHAPTER ONE

 

 

1: Account for the apparent motions of the Sun, Moon, and stars in terms of the actual motions of Earth and the Moon.

2: How the relative motions of Earth, the Sun, and the Moon lead to eclipses.

3: how the observed motions of the planets led to our modern view of a Sun-centered solar system.

4: Contributions of Galileo and Kepler to the development of our understanding of the solar system.

5: Kepler's laws of planetary motion.

6: Newton's laws of motion and his law of universal gravitation.

 

 

 

 

 

 

SOLAR DAY: The time from one sunrise to the next is called a solar day.

SIDEREAL DAY: The time between successive rising of any given star is called a Sidereal day. Because of Earth’s revolution around the sun, the solar day is a 3.9 minutes longer than the Sidereal Day.

ECLIPTIC : The Sun’s yearly path around the celestial sphere or, equivalently, the plane of Earth's orbit around the Sun is called the ecliptic.

ZODIAC: The twelve constellations lying along the ecliptic are collectively called the zodiac

SEASONS : Because Earth’s axis is inclined to the ecliptic plane (23.5o ) we experience seasons, depending on which hemisphere ( northern or southern ) happened to be ‘tipped” toward the Sun.

 

 

 

 

 

 

 

THE SUN AND THE SEASONS

People have always watched the sun for signs of the passing seasons. Those living in the Northern Hemisphere learned early that the noon sun is highest in the sky about June 22 and lowest about December 22. These positions are called the solstices.

SUMMER SOLSTICE: The Sun is the highest in the sky, and the length of the day is greatest.

WINTER SOLSTICE: The Sun is the lowest in the sky, and the length of the day is shortest.

VERNAL EQUINOXES: The date on which the sun crosses the celestial equator moving northward, occurring on or near March 21.

AUTUMNAL EQUINOXES: The date on which the sun crosses the celestial equator moving southward, occurring on or near September 22.

 

 

 

APPARENT CHANGES OF SUN’S POSITION:

   Two facts account for the apparent changes in the sun's position. First, the Earth revolves around the sun once during the year while rotating daily on its own axis. Second, the Earth's axis is tilted about 23 1/2 degrees from the vertical. Thus in June the Northern Hemisphere is tipped slightly toward the sun, and the Southern Hemisphere slightly away from the sun. In December the opposite is true. In March and September both hemispheres are equally exposed to the sun.

TROPICAL YEAR: The time interval between one vernal equinoxes and the next is one tropical year .

SIDEREAL YEAR: The time required for the same zodiac constellations to reappear at the same location in the sky, as viewed from a given point on Earth, is one sidereal year.

 

 

 

 

 

PRECESSION: The slow change in the direction of the axis of a spinning object, caused by some external force.

 

EARTH PRECESSION: In addition to its rotation about its axis and its revolution around the Sun, Earth undergoes a motion called precession , where the influence of the Moon causes Earth's axis to wobble slightly. As a result, the particular constellations that happen to be visible on any given night change slowly over the course of many years.

 

 

 

 

 

 

 

 

 

 

 

 

NOTE: It takes 365 days the Earth orbits once the sun, and 24 hours to orbit around its axis.

 

 

 

Day                           Angle

 

365                            360

 

  1                                 x = 360/365 = 0.9860 

 

 

Hours                  Angle

 

24                          360                    24 x 0.986

 

Y                         0.986     

 

 

               24 x 0.986

  Y = -------------------- =  0.0657 h = 3.94 minutes

                   360

 

 

 

 

 

THE MOTION OF THE MOON

 

The Moon our nearest neighbor in space. It emits no light of its own. It shines by reflected sunlight.

 

LUNAR PHASE: The appearance of the Moon at different points along its orbit is called LUNAR PHASE.

 

FULL MOON: At full Moon the entire illuminated side can be seen.

 

QUARTER MOON: At quarter Moon only the half  illuminated side can be seen.

 

NEW MOON: At new Moon illuminated side points away Earth, and the Moon is invisible from Earth.

 

 

 

 

 

SYNODIC MONTH: Time required for the Moon to complete a full cycle of its phases is called synodic month.( 29.5 days)

 

SIDEREAL MONTH: Time required for the Moon to complete one trip around the celestial sphere is called sidereal month.( 27.3 days)

 

ASTRONOMICAL ALIGNMENTS

ECLIPSE: . The eclipse is named for the object that is being eclipsed, or obscured. eclipse have long been a source of mystery and spectacle. These events were viewed with fear and dread in the past and, even today, still thrill.

LUNAR ECLIPSE: A celestial event during which the Moon passes through the shadow of the Earth, temporarily darkening its surface. The eclipse may be total, if the entire Moon is temporarily darkened, or partial, if only a portion of the Moon’s surface is affected.

 

 

 

 

SOLAR ECLIPSE: A celestial event during which the Moon passes directly between the Earth and the Sun, temporarily blocking the Sun’s light.