Transcript PHYS 3380 - Astronomy - The University of Texas at Dallas

PHYS 3380 - Astronomy
PHYS 3380 - Astronomy
Dr. Phillip Anderson
PHYS 3380 - Astronomy
PHYS 3380 - Astronomy
Fall 2016
– INSTRUCTOR:
– Dr. Phillip C. Anderson 972-883-2875 — Room PHYS 1.912
(and WSTC1.720)
email: [email protected]
– TEACHING ASSISTANT:
– Tianle Guo
– [email protected]
– OFFICE HOURS:
– Dr. Anderson: MW 12:00 PM – 2:00 PM and by appointment
– Mr Guo: M 10:00 AM – 12:00 PM, PHYS 1.102, Table 17
PHYS 3380 - Astronomy
Fall 2016
TEXT:
– Foundations of Astronomy, Seeds, 12th Edition
See me if you have an older edition
– Slides will be available on web at www.utdallas.edu/~pca015000
GRADING:
– Exams (3)
2 Exams (Oct 5, Nov 9) @ 20% each
= 40%
Final Exam (TBD)
= 30%
– Homework
= 20%
Homework will be assigned weekly and will
be due a week later. Late homework will not be accepted. It is
considered late after 3:45 PM seven days after assigned unless
otherwise specified. .
– Projects
= 10%
– Attendance will be taken every class period and will be used to decide
whether to raise or lower grades on the cusp.
PHYS 3380 - Astronomy
Follow the links to each class’s notes(at www.utdallas.edu/~pca015000)
They will be available at least the day before the class.
Any movies in the notes will be separated out and put in a separate
directory. They can be played with Quicktime or may be html animations
that can be run through your web browser.
The exams will only cover material discussed in class. It would behoove
you to read the relevant material in the book before/after class as it may
provide a different perspective on the material that will help you understand
it better than the lecture and class notes alone. Note that some of the
material covered in the lecture will not be in the text - it is very important to
attend class.
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Project 1
1. Find a location from where you can observe either the sunrise or sunset. Note
some landmarks, such as trees or light poles, etc. Make a sketch of the location and
on the sketch plot the position on the horizon that the sun either rises or sets
(morning or evening). Record the date and the time when you first see the sun rise
or last see it set. Do this about once per week consistent with weather conditions.
You MUST have at least 3 months of observations.
2. Write a three to four page paper on:
A. How and where you made your observations.
B. How did the sunrise or sunset position change with time?
C. How fast did it change? Was the change uniform over the three month
period?
D. Why did the sunrise or sunset position move as you observed it.
E. What problems did you encounter in doing this project and how did you
solve those problems?
3.
The project is to be turned at the final (TBD).
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Project 2
1. Plot the location and phase of moon over a complete synodic month, e.g., from
new moon to new moon on an all-sky diagram as shown below. In an all-sky
diagram, zenith is at the center and the edge of the circle is the horizon with the
compass points indicated as in the figure. Estimate the compass direction of the
moon (use a compass or the north star) and the angle of the moon above the
horizon. Plot its location on the diagram using:
(distance from edge of the circle to moon location)/radius = (angle above
the horizon)/90
location around circle = cardinal direction (N,S,E,W)
PHYS 3380 - Astronomy
In the example in the diagram, the moon is in the southeast, 30 degrees above the
horizon.
Draw a picture of the moon at the location as it appears, in other words its phase.
Do it at the same time every night. Obviously there will be times when the weather
does not cooperate but there should be at least 15 nights in which you perform the
observation.
PHYS 3380 - Astronomy
2. Write a three to four page paper on:
A.
How and where you made your observations.
B.
How did the moon’s position and appearance change with time?
C. How fast did they change? Was the change uniform over the
observation period?
D.
Why did the moon’s position and appearance move as you observed it?
E. What problems did you encounter in doing this project and how did you
solve those problems?
3. The project is to be turned in at the final (TBD).
PHYS 3380 - Astronomy
Making a sextant out of a protractor
Buy a large protractor. Glue a fat
drinking straw to the protractor,
with the straw going through the
90 and 270 degree marks, and
running right through the center of
the protractor (you can actually do
it without the straw); then drill a
small hole in the center (if there
isn't one there already) and hang
a weight from the hole (a fishing
line and weight works quite
nicely), so that the weight hangs
just outside the circumference of
the protractor. Once this is set up,
if you hold the protractor in a
vertical plane, so the weight
hangs straight down at its side,
and point the straw at the moon,
so you can see the moon through
the straw, the line holding the
weight will indicate the Altitude of
the moon.
PHYS 3380 - Astronomy
SYLLABUS - Fall 2016
Chapters 1 ,2, & 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 9
Chapters 10 & 11
Chapter 12
Chapters 13 & 14
Chapters 15 & 16
Chapter 18
Chapter 26
The Night Sky
History of Modern Astronomy
Newton, Einstein, and Gravity
Light and Telescopes
Information from Distant Objects
The Sun
Determining the Observable Properties of Stars
Interstellar Medium and Star Formation
The Evolution of Stars
The Deaths of Stars
Galaxies
Cosmology
Life in the Universe
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SCALES OF DISTANCE
Astronomical AU Average distance between the Earth and the Sun
Unit
Light Year
LY
Distance light travels in one Year
1 LY = 3 x 108 m/s X 31,500,000 s/yr = 9.45 x
1015 m
Parsec
PC Distance of an object that would have a stellar
parallax of 1 Second of Arc
1 PC = 3.26 LY = 206,000 AU
Angstrom
A
Nanometer
nm A distance of 10-9 meter or 10-7 cm
Visible light has wavelengths from 400 to 700 nm
A distance of 1x10-8 cm
Visible Light has wavelengths from 4000 to 7000 A
PHYS 3380 - Astronomy
Our Place in the Cosmos
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Light Travel Time
From Earth to the Moon
our natural satellite
From Earth to the Sun
the centre of our Solar System
From the Sun to Jupiter
the largest planet
From the Sun to Saturn
the furthest naked eye planet
From the Sun to Pluto
From the Sun to Alpha Centauri
the nearest star to us
From the Sun to Sirius
the brightest star in our sky
Distance where the Sun would no longer be visible to naked eye
From the Sun to Polaris
the north pole star
From the Sun to the Galactic
the centre of our Galaxy
centre
Galactic diameter
the diameter of our Galaxy
To the Andromeda Galaxy
the nearest large galaxy
Extinction of the dinosaurs
To Q0134+329
typical quasar
Formation of the Earth and Sun
To remotest quasars
discovered in 1998
Edge of Universe
limit of observable Universe
1.25 seconds
8.3 min
41 min
85 min
5.5 hr
4.3 yr
8.6 yr
60 yr
650 yr
31,000 yr
81,500 yr
2,200,000 yr
65,000,000 yr
4,500,000,000 yr
4,700,000,000 yr
14,000,000,000 yr
15,000,000,000 yr
PHYS 3380 - Astronomy
1.25 s
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The Solar System
8.3 min
41 min
85 min
5.5 hr
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Alpha Centauri - closest star - 4.3 LY
Our Milky Way Galaxy
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The Milky Way
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Spiral Galaxies Similar
to the Milky Way
Edge view
View from above
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The Milky Way
The Sun is located on
the Orion spiral arm
about 30,000 LY from
the galactic center
It takes about 230 million
years for the sun to
complete one orbit around
the galactic center
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Other Galaxies in
Our Local Group
A Ring Galaxy
The Andromeda Galaxy
2.3 million LY away
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Deep field view - about 10 billion LY away
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 In our galaxy there are about 200 billion stars
 In our universe there are over 100 billion galaxies
There are more stars in the universe than
there are grains of sand on the Earth
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If the Universe was one year old (instead of 13.7 billion years)
The Cosmic Calendar (Carl Sagan)
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1027 meters = 1000 yottameters
100 Billion Light Years
This image represents the size of the known universe -- a
sphere with a radius of 13.7 billion light years.
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1026 meters = 100 yottameters
Ten Billion Light Years
Light from galaxies on the edge would require 5 billion years to reach the
center. Observers at the center are seeing light that was emitted by these
galaxies before the solar system formed. The largest scale picture ever taken.
Each of the 9325 points is a galaxy like ours. They clump together in
'superclusters' around great voids which can be 150 million light years
across.
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1025 meters = 10 yottameters
One Billion Light Years
Astronomers have determined that the largest structures within the
visible universe - superclusters, walls, and sheets - are about 200 million
light years on a side.
PHYS 3380 - Astronomy
1024 meters = 1 yottameter
100 Million Light Years
Clusters of Galaxies
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1023 meters = 100 zettameters
10 Million Light Years
Within the Virgo Cluster
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1022 meters = 10 zettameters
1 Million Light Years
The Local Group - Our galaxy with the Magellanic
Clouds - two companion galaxies on the right.
PHYS 3380 - Astronomy
1021 meters = 1 zettameter
100,000 Light Years
Our galaxy - the Milky Way - looks rather like a whirlpool. It has spiral
arms curling outwards from the center and rotates at about 900
kilometres per hour. It contains about 200 billion stars.
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1020 meters = 100 exameters
10,000 Light Years
Our Spiral Arm
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1019 meters = 10 exameters
1,000 Light Years
The Stars of the Orion Arm
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1018 meters = 1 exameter
100 Light Years
Stars within 50 Light Years
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1017 meters = 100 petameters
10 Light Years
The Nearest Stars
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1016 meters = 10 petameters
1 Light Year
The Oort Cloud
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1015 meters = 1 petameter
0.1 Light Year
Sol - our Sun
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1014 meters = 100 terameters
Our Sun and a few rocks
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1013 meters = 10 terameters
The solar system. Only the orbit
of Pluto is off the picture.
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1012 meters = 1 terameter
Within the orbit of Jupiter - the orbits of the inner four planets
: Mercury, Venus, Earth and Mars. All four have rocky crusts
and metallic cores.
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1011 meters = 100 gigameters
Six weeks of the Earth's orbit. The orbits of Venus
and Mars are just visible on either side.
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1010 meters = 10 gigameters
Four days of the Earth's orbit.
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109 meters = 1 gigameter
The moon's orbit around the Earth, the
furthest humans have ever traveled.
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108 meters = 100 megameters
Earth
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107 meters = 10 megameters
North and Central America
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106 meters = 1 megameter
California
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105 meters = 100 kilometer
The San Francisco Bay Area
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104 meters = 10 kilometers
San Francisco
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103 meters = 1 kilometer
Golden Gate Park
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102 meters = 100 meters
Japanese Tea Garden - one hectare (10,000 m2)
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101 meters = 10 meters
A pond with lily pads
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100 meters = 1 meter
A one-meter square
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10-1 meters = 10 centimeters
A bee on a lily pad flower
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10-2 meters = 1 centimeter
A bee's head
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10-3 meters = 1 millimeter
A bee's eye
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10-4 meters = 100 micrometers
Pollen
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10-5 meters = 10 micrometers
Bacteria
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10-6 meters = 1 micrometer
Virus on a bacterium
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10-7 meters = 100 nanometers
A virus
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10-8 meters = 10 nanometers
The structure of DNA
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10-9 meters = 1 nanometer
The molecules of DNA
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10-10 meters = 100 picometers
Carbon's outer electron shell
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10-11 meters = 10 picometers
The inner electron cloud
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10-12 meters = 1 picometer
Within the electron cloud
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10-13 meters = 100 femtometers
The nucleus
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10-14 meters = 10 femtometers
The nucleus of carbon
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10-15 meters = 1 femtometer
A proton
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10-16 meters = 100 attometers
Within the proton
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10-17 meters = 10 attometers
Quarks and gluons
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Constellations
Constellations - groupings of stars named after mythical heroes, gods, and
mystical beasts
- made up over at least the last 6000 years - maybe more
- used to identify seasons:
- farmers know that for most crops, you plant in the spring and harvest in
the fall.
- in some regions, not much differentiation between the seasons.
- different constellations visible at different times of the year - can use
them to tell what month it is. For example, Scorpius is only visible in
the northern hemisphere's evening sky in the summer.
- many of the myths associated with the constellations thought to have
been invented to help the farmers remember them - made up stories
about them
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Picture at right shows a start chart of the region around the constellation Orion.
Picture at the left is an ornate star chart printed in 1835 - shows the great hunter
Orion. He is holding a lion's head instead of his traditional bow or shield. He is
stalking Taurus, the Bull in the upper right hand corner. Behind him, his faithful
dog, Canis Major, is chasing Lepus, the Hare.
PHYS 3380 - Astronomy
Constellations
Western culture constellations originated in Mesopotamia over 5000 years agoadded to by Babylonian, Egyptian, and Greek astronomers - current list is based on
those listed by the Roman astronomer, Claudius Ptolemy (~140 AD)
In modern world - constellations redefined so
now every star in the sky is in exactly one
constellation.
In 1929, the International Astronomical Union
(IAU) adopted official constellation
boundaries that defined the 88 official
constellations that exist today.
asterisms - less formally defined groupings
- Big Dipper - part of Ursa Major
- Start clusters - Beehive,
Pleiades, etc
- Orion’s belt
- Northern Cross - formed by the
leading stars of the constellation
Cygnus
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The Orion Nebula
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Nebula - an interstellar cloud
of dust, hydrogen gas and
plasma.
One of the most beautiful
sights in the universe
Birthplaces of stars
Nebulae
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The Orion Nebula
Located in the sword of the constellation Orion.
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The Orion Nebula
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Proplyds or Proto Solar Systems in the Orion Nebula
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Gaseous Pillars - Stellar Nursery