Astronomy 105 ä Student Information Sheet ä Class Syllabus ä Lab Syllabus ä Course Supplies ä...
-
Upload
samuel-dixon -
Category
Documents
-
view
224 -
download
2
Transcript of Astronomy 105 ä Student Information Sheet ä Class Syllabus ä Lab Syllabus ä Course Supplies ä...
Astronomy 105Astronomy 105 Student Information SheetStudent Information Sheet Class SyllabusClass Syllabus Lab SyllabusLab Syllabus Course SuppliesCourse Supplies
TextTextLab ManualLab ManualScantron 882-ESScantron 882-ESFlashlight with red filterFlashlight with red filter
In Search of E.T.'s Breath
This is AstronomyThis is Astronomy
……not astrologynot astrology..
A Sense of ScaleA Sense of Scale
The Earth- 13,000km=13x10The Earth- 13,000km=13x1033km (8080 miles) Solar System- 6,000,000,000km=6x10Solar System- 6,000,000,000km=6x1099km km
(4 x 10(4 x 1099 miles) miles) The Milky Way Galaxy-10The Milky Way Galaxy-101818km(6x10km(6x101818 miles) miles) Local Group of Galaxies-10Local Group of Galaxies-102121km(6x10km(6x102121miles)miles) Universe-bigger than we can imagine.Universe-bigger than we can imagine.
The Earth
The Sun
A Typical Galaxy
1 light year = 10,000,000,000,000 km 6,000,000,000,000 miles (10 trillion km) (6 trillion miles)
QuestionsQuestions
How many stars can one see on a clear How many stars can one see on a clear night”night”
Approximately 3000.Approximately 3000. What is the closest star to Earth?What is the closest star to Earth? The sunThe sun On what horizon do stars rise? Set?On what horizon do stars rise? Set? Rise from eastRise from east - Set in the west- Set in the west
The UniverseThe Universe the totality of all space, time, matter and energythe totality of all space, time, matter and energy
AstronomyAstronomy the study of the universethe study of the universe
Light YearLight Year the distance traveled by a beam of light in one the distance traveled by a beam of light in one
yearyear
The Sky CalendarThe Sky Calendar
The sky is a master calendar.The sky is a master calendar. DayDay
the time for one Earth rotation.the time for one Earth rotation. YearYear
the time for one Earth orbit around the Sunthe time for one Earth orbit around the Sun MonthMonth
the approximate time for the Moon to orbit the the approximate time for the Moon to orbit the EarthEarth
Solar DayThe time from one noon to the next. This is our 24 hr day.
Sidereal DayA day measured by the slight shift of the stars positions from one evening to the next. This is roughly 23h, 56min. the Solar Day is approximately 4min. longer than the sidereal day.
Solar Day and Sidereal Day
The Difference Between a Solar Day and a Sidereal Day.
Synodic Month and Sidereal Month
The time it takes the moon to complete one revolution around the Earth. (27.3 solar days)
Synodic (Lunar) MonthThe time it takes the moon to complete one full cycle of phases, from one new moon to the next new moon) (29.5 solar days)
Sidereal Month
Sidereal Month and Synodic Month
Tropical Year and Sidereal Year
Tropical YearThe time interval from one vernal equinox to the next. (365.242 mean solar days)
Sidereal YearThe time required for the Earth to complete one orbit around the Sun, relative to the stars.
(365.256 mean solar days – about 20 minutes longer than a tropical year.)
The tropical year is the year our calendars measure.
Vernal Equinox
360o = 24h
Or 15o/h
Note:
altitudealtitude - the angle of a star above the horizon - the angle of a star above the horizon
The The North StarNorth Star, Polaris, is not the brightest star , Polaris, is not the brightest star in the sky but remains in a fixed position in the in the sky but remains in a fixed position in the sky. (near the North Celestial Pole)sky. (near the North Celestial Pole)
The angle of Polaris above your horizon is the The angle of Polaris above your horizon is the same as your same as your latitudelatitude in degrees. in degrees.
QuestionsQuestions
Ans: 31Ans: 31oo 45 45’’ 35.3 35.3’’’’= 31.7598= 31.7598oo
Where are you if Polaris is directly overhead?Where are you if Polaris is directly overhead?
Where are you if Polaris is on your horizon?Where are you if Polaris is on your horizon?
What is the altitude of Polaris in Nacogdoches?What is the altitude of Polaris in Nacogdoches?
Ans: North PoleAns: North Pole
Ans: EquatorAns: Equator
Longitude: -94 39 40.5 = -94.6613
Our Latitude
View from the EquatorView from the Equator
View from the North PoleView from the North Pole
Circumpolar StarsCircumpolar Stars
ConstellationsConstellations
ConstellationsConstellations are recognizable patterns of are recognizable patterns of stars in the sky. (Based on stories and stars in the sky. (Based on stories and named in honor of them)named in honor of them)
There are 88 constellations. (e.g. Orion) There are 88 constellations. (e.g. Orion)
The 12 constellations along the ecliptic on The 12 constellations along the ecliptic on your star chart are called the your star chart are called the Zodiac Zodiac ConstellationsConstellations..
AsterismsAsterisms
AsterismAsterism is a recognizable pattern of stars is a recognizable pattern of stars that is not one of the 88 constellations.that is not one of the 88 constellations.
For Example: The Big DipperFor Example: The Big Dipper
Asterisms developed as navigational tools for early seafarers.
Asterisms can include parts of constellations (subsets), or can include two or more constellations (supersets).
SeasonsSeasons
The path of our Sun across the celestial sphere The path of our Sun across the celestial sphere is called the is called the eclipticecliptic. It is inclined 23½° with . It is inclined 23½° with respect to the respect to the celestial equatorcelestial equator..
What causes seasons on Earth?What causes seasons on Earth?
Answer: The tilt of the Earth's rotational axis.Answer: The tilt of the Earth's rotational axis.
Inclined Pole causes SeasonsInclined Pole causes Seasons
Ecliptic
Horizon CalendarHorizon Calendar
June(Summer Solstice)
March & September(Equinoxes)
December(Winter Solstice)
Longest day in Northern
Hemisphere
Shortest Day in Southern Hemisphere.
Shortest day in
Northern Hemisphere
Longest Day in Southern Hemisphere.
Day and Night are equal duration.
Motions of the Sun and StarsMotions of the Sun and StarsMotions of the Sun and StarsMotions of the Sun and Stars
Daily MotionDaily MotionThe rising and setting of the stars is The rising and setting of the stars is
caused by the caused by the Earth’s rotationEarth’s rotation about its about its axis.axis.
Annual MotionAnnual MotionThe The Earth’s orbitEarth’s orbit around the Sun causes around the Sun causes
different stars to be visible at different different stars to be visible at different times during the year.times during the year.
PrecessionPrecession
PrecessionPrecession is the slow wobble of the is the slow wobble of the Earth’s axis due to the influence of the Earth’s axis due to the influence of the Moon.Moon.
Precession – The Earth wobbles like a spinning top!Precession – The Earth wobbles like a spinning top!
The Lunar PhasesThe Lunar PhasesThe Lunar PhasesThe Lunar Phases
As the moon orbits the Earth, the moon goes As the moon orbits the Earth, the moon goes through through phases phases. Since the name of our moon is . Since the name of our moon is Luna, these are called Luna, these are called Lunar PhasesLunar Phases..
Eclipses
Why Don’t We Have a Lunar Eclipse Every Month?
Ans: The orbit of the moon is also tilted!!
Eclipses
A A solar eclipsesolar eclipse occurs when the Moon occurs when the Moon passes between the sun and the earth.passes between the sun and the earth.
A A lunar eclipselunar eclipse occurs when the Moon occurs when the Moon passes behind the Earth's shadow.passes behind the Earth's shadow.
Note: The shape of the Earth was Note: The shape of the Earth was determined by observing the shape of this determined by observing the shape of this shadow.shadow.
New MoonFull Moon
1st Quarter
3rd Quarter
Triangulation
Triangulation
A triangle of fixed baseline is narrower the farther away the object.
BASELINE
Measuring a Star’s DistanceMeasuring a Star’s DistanceMeasuring a Star’s DistanceMeasuring a Star’s Distance
ParallaxParallax - the apparent change in the - the apparent change in the position of a star due to the motion of the position of a star due to the motion of the EarthEarth
Nearby objects exhibit more parallax than Nearby objects exhibit more parallax than remote ones.remote ones.
Stellar ParallaxStellar Parallax
Sun
January
June
Nearby Star
Parallax
Distance ~ 1/Parallax angle
Parallax
Angle
End of Section...End of Section...