NATS 1311 - From the Cosmos to Earth
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Spiral Galaxies Similar to the Milky Way PowerPoint PPT Presentation


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Spiral Galaxies Similar to the Milky Way. Edge view. View from above. 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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Spiral Galaxies Similar to the Milky Way

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Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

Spiral Galaxies Similar to the Milky Way

Edge view

View from above


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

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


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

Other Galaxies in Our Local Group

A Ring Galaxy

The Andromeda Galaxy

2.3 million LY away


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

Deep field view - about 10 billion LY away


Spiral galaxies similar to the milky way

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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


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

If the Universe was one year old (instead of 15 billion years)

The Cosmic Calendar (Carl Sagan)


Spiral galaxies similar to the milky way

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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.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

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.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

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.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

1024 meters = 1 yottameter

100 Million Light Years

Clusters of Galaxies


Spiral galaxies similar to the milky way

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1023 meters = 100 zettameters

10 Million Light Years

Within the Virgo Cluster


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

1022 meters = 10 zettameters

1 Million Light Years

The Local Group - Our galaxy with the Magellanic

Clouds - two companion galaxies on the right.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

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.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

1020 meters = 100 exameters

10,000 Light Years

Our Spiral Arm


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

1019 meters = 10 exameters

1,000 Light Years

The Stars of the Orion Arm


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NATS 1311 - From the Cosmos to Earth

1018 meters = 1 exameter

100 Light Years

Stars within 50 Light Years


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NATS 1311 - From the Cosmos to Earth

1017 meters = 100 petameters

10 Light Years

The Nearest Stars


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NATS 1311 - From the Cosmos to Earth

1016 meters = 10 petameters

1 Light Year

The Oort Cloud


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NATS 1311 - From the Cosmos to Earth

1015 meters = 1 petameter

0.1 Light Year

Sol - our Sun


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

1014 meters = 100 terameters

Our Sun and a few rocks


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

1013 meters = 10 terameters

The solar system. Only the orbit of Pluto, the furthest planet from the Sun, is off the picture.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

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.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

1011 meters = 100 gigameters

Six weeks of the Earth's orbit. The orbits of Venus and Mars are just visible on either side.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

1010 meters = 10 gigameters

Four days of the Earth's orbit.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

109 meters = 1 gigameter

The moon's orbit around the Earth, the furthest humans have ever traveled.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

108 meters = 100 megameters

Earth


Spiral galaxies similar to the milky way

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107 meters = 10 megameters

North and Central America


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

106 meters = 1 megameter

California


Spiral galaxies similar to the milky way

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105 meters = 100 kilometer

The San Francisco Bay Area


Spiral galaxies similar to the milky way

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104 meters = 10 kilometers

San Francisco


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

103 meters = 1 kilometer

Golden Gate Park


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

102 meters = 100 meters

Japanese Tea Garden - one hectare (10,000 m2)


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

101 meters = 10 meters

A pond with lily pads


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

100 meters = 1 meter

A one-meter square


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

10-1 meters = 10 centimeters

A bee on a lily pad flower


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

10-2 meters = 1 centimeter

A bee's head


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

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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NATS 1311 - From the Cosmos to Earth

10-11 meters = 10 picometers

The inner electron cloud


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NATS 1311 - From the Cosmos to Earth

10-12 meters = 1 picometer

Within the electron cloud


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10-13 meters = 100 femtometers

The nucleus


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NATS 1311 - From the Cosmos to Earth

10-14 meters = 10 femtometers

The nucleus of carbon


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NATS 1311 - From the Cosmos to Earth

10-15 meters = 1 femtometer

A proton


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NATS 1311 - From the Cosmos to Earth

10-16 meters = 100 attometers

Within the proton


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NATS 1311 - From the Cosmos to Earth

10-17 meters = 10 attometers

Quarks and gluons


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NATS 1311 - From the Cosmos to Earth

We are “Star Stuff”


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NATS 1311 - From the Cosmos to Earth

The Orion Nebula

Located in the sword of the constellation Orion.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

The Orion Nebula


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

The Orion Nebula


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NATS 1311 - From the Cosmos to Earth

Proplyds or Proto Solar Systems in the Orion Nebula


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NATS 1311 - From the Cosmos to Earth

Gaseous Pillars - Stellar Nursery


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

Science

What is Science?

  • Observation and experimentation directed toward understanding of the natural world.

    Why study science?

  • We live in a world surrounded by science and technology.

  • Our problems and their solutions are bound up with science.

  • We are called upon to make decisions, to vote, hopefully informed, on issues affecting our lives.

  • Many of these issues have a significant scientific component.


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NATS 1311 - From the Cosmos to Earth

Why study science? (Continued)

  • For the convenience of the study of science, the subject is frequently divided into neat packages called biology, chemistry, geology, physics, astronomy ---

  • Nature is not so divided - Each scientific discipline views nature from a different perspective, but all are studying the same world.

  • This course will focus on a fundamental or general look at nature. It will be based on physics, the study of the principles that govern the natural world.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

Why are we able to study nature?

  • Fundamental assumptions about nature:

    • Order exists in nature – in the universe.

    • Order can be discovered by observation and experimentation.

    • Laws of nature are constant in time and place.

      Philosophical approach to the study of nature.

  • Aristotle, Plato

    • Senses cannot be relied on

    • Must use reason and insights of human mind.


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Scientific approach to the study of nature

  • Copernicus and Galileo introduced observation and experimentation in the 16th century.

  • Science is not a set of facts.

  • It is a way of conducting a dialogue about our physical surroundings.

  • The scientific method consists of careful observation of nature and an open-minded creative search for general ideas that agree with and predict those observations.

  • To be scientific, a statement must be capable of being proven wrong.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

Scientific approach to the study of nature.

  • Observation and experimentation set science apart from other ways of knowing - ways that are not less important - just different

    • Philosophy – Reason – Logic

    • Art – Appreciation of form – Beauty

  • Pseudosciencestatements:

    – Hypothesis that cannot be tested with reproducible results;

    Cold fusion, ufo's, astrology. . .


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

Scientific approach to the study of nature.

  • Scientific Law:

    • Statement of observed regularity in nature - attempts to describe the observations

    • has a well documented history of successful replication and extension to new conditions

  • Scientific Theory:

    • Statement of observed regularity in nature - attempts to explain the observations

    • General principle offered to explain a set of phenomena or observed facts.

    • Not all scientific predictions can be tested directly

      • Core of earth

      • Sun—energy

      • Expansion of the universe

  • Require models—creative thought

    • No ultimate truths—all Provisional

      • Ok as long as they are not contradicted


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

Scientific approach to the study of nature.

  • Model:

    • Simplified version of reality used to describe aspects of nature.

    • Not synonymous with reality.

    • Based on assumptions that may simplify some aspects of nature, or may be incomplete statements about nature

    • Useful to make predictions that can be verified by experimentation or observation.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

The Scientific Method


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Hallmarks of Science

  • Modern science seeks explanations for observed phenomena that rely solely on natural causes.

  • Science progresses through the creation and testing of models of nature that explain the observations as simply as possible.

  • A scientific model must make testable predictions about natural phenomena that would force us to revise or abandon the model if the predictions do not agree with observations.


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NATS 1311 - From the Cosmos to Earth

Occam’s Razor

The idea that scientists should prefer the simpler of two models that agree equally well with observations - the second hallmark - after medieval scholar William of Occam (1285 - 1349).

For instance, original model of Copernicus (Sun-centered) did not match the data noticeably better than Ptolemy's model (Earth-centered). Thus, a purely data-driven judgment based on the third hallmark might have led scientists to immediately reject the Sun-centered idea. Instead, many scientists found elements of the Copernican model appealing, such as the simplicity of its explanation for apparent retrograde motion. Was kept alive until Kepler found a way to make it work.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

The most exciting words in science are

not “Eureka (I found it)” but “Now that’s

funny”.


Motions of earth

NATS 1311 - From the Cosmos to Earth

MOTIONS OFEARTH

1. ROTATION ON ITS AXIS - Day

2. REVOLUTION ABOUT SUN- Year

3. PRECESSION- Wobble of spin axis


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

Motions of Earth


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

Rotation

The Earth rotates about its axis axis once per day - one rotation equals one day. The axis goes through the north and south poles and through the center of the Earth. It rotates counterclockwise when looking down on the north pole which means that the sun rises in the east and sets in the west.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

The Rotation of the Earth From Space


Spiral galaxies similar to the milky way

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Earth’s rotation causes the stars - the celestial sphere - to appear to rotate around the Earth. Viewed from outside, the stars (and the Sun, Moon, and planets) therefore appear to make simple daily circles around us. The red circles represent the apparent daily paths of a few selected stars.


The celestial sphere

NATS 1311 - From the Cosmos to Earth

The Celestial Sphere

Envisioned by the ancients, the celestial sphere had Earth at the center with the stars emblazoned on the sphere. They thought the stars rose and set because the celestial sphere (the sky) rotated, carrying the stars from east to west. All stars appear to move around two points on the celestial sphere, the north and south celestial poles—projections of earth’s axis of rotation. Earth's equator projected on the celestial sphere becomes the celestial equator.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

Our lack of depth perception when we look into space creates the illusion that the Earth is surrounded by a celestial sphere. Thus, stars that appear very close to one another in our sky may actually lie at very different distances from Earth.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

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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NATS 1311 - From the Cosmos to Earth

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.


Spiral galaxies similar to the milky way

NATS 1311 - From the Cosmos to Earth

Constellations

Western culture constellations originated in Mesopotamia over 5000 years ago - added to by Babylonian, Egyptian, and Greek astronomers - current list based charts of 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.


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