Transcript Overview of Astronomy 150

How to succeed in this course
• Come to class.
– We will be doing exam questions almost everyday in class.
• Take notes as we go, reread and highlight the important
points after each class.
• Do all projects on time
• Do the questions in the tutorials
– Also, try tutorials on the mastering astronomy website.
• Work in pairs\groups.
– But remember whatever you submit must be in your own words.
• If you have a course related problem, let me know ASAP.
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Our Place in the Universe
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What is our place in the universe?
Our “cosmic address”
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Universe
The sum total of all matter and energy;
that is, everything within and between
all galaxies
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Nebula
An interstellar cloud
of gas and/or dust
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Galaxy
A great island of stars in space, all held
together by gravity and orbiting a
common center
M31, theM31,
Great
theGalaxy
great galaxy in
in AndromedaAndromeda
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How did we come to be?
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• At great distances, we see objects as they were
when the universe was much younger.
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How can we know what the universe was
like in the past?
• Light travels at a finite speed (300,000 km/s).
Destination
Light travel time
Moon
1 second
Sun
8 minutes
Sirius
8 years
Andromeda Galaxy
2.5 million years
• Thus, we see objects as they were in the past:
The farther away we look in distance,
the further back we look in time.
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Definition: Light-Year
• The distance light can travel in 1 year
• About 10 trillion kilometers (6 trillion
miles)
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How did we come to be?
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How did we come to be?
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How did we come to be?
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Example:
This photo shows the Andromeda Galaxy.
Question: When will we be able to see Andromeda as it is now?
A. Never.
B. 2.5 million years from
now.
C. Today.
D. There is no way to know.
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Solar (Star) System
A star and all the material that orbits
it, including its planets and moons
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Star
A large, glowing ball of gas that generates heat and
light through nuclear fusion
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Planet
Mars
Uranus
A moderately large object that orbits a star; it
shines by reflected light. Planets may be rocky,
icy, or gaseous in composition.
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Moon (or satellite)
An object that orbits
a planet
Ganymede (orbits Jupiter)
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Asteroid
A relatively small
and rocky object
that orbits a star
Computer model from RADAR Measurements
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Comet
A relatively
small and icy
object that
orbits a star
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How did we come to be?
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Put these objects in the correct
order, from nearest to farthest
from Earth:
A. The Sun, the Milky Way, Sirius, Jupiter, the Andromeda
galaxy
B. The Sun, Sirius, Jupiter, the Andromeda galaxy, the Milky
Way
C. The Sun, Jupiter, Sirius, the Milky Way, the Andromeda
galaxy
D. Jupiter, the Sun, Sirius, the Milky Way, the Andromeda
galaxy
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Put these objects in the correct
order, from nearest to farthest
from Earth:
A.
B.
C.
D.
The Moon, Mars, the Sun, the nearest stars, Pluto
The Moon, Mars, the Sun, Pluto, the nearest stars
The Moon, the Sun, Mars, Pluto, the nearest stars
Mars, the Moon, the Sun, the nearest stars, Pluto
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The Local Group
The Andromeda Galaxy
• The Andromeda Galaxy is
the nearest large galaxy to
the Milky Way.
• It is 2.5 million light years
away.
• It takes the light from the
stars and gas in
Andromeda 2.5 million
years to get to us.
• That means, we see
Andromeda as it was 2.5
million years ago.
Tutorial: Looking At Distant
Objects
• Work with a partner!
• Read the instructions and questions carefully.
• Discuss the concepts and your answers with one
another. Take time to understand it now!!!!
• Come to a consensus answer you both agree
on.
• If you get stuck or are not sure of your answer,
ask another group.
Imagine that you simultaneously receive the satellite
transmission of two pictures of two people that live on
planets orbiting two different stars. Each image shows the
people at their 21st birthday parties. Consider the following
possible interpretations that could be made from your
observations.
Which do you think is the most plausible interpretation?
1. Both people are the same age but at different distances
from you.
2. The people are actually different ages but at the same
distance from you.
3. The person that is closer to you is actually the older of the
two people.
4. The person that is farther from you is actually the older of
the two people
Fifteen years ago, a quasar was observed
that was found to be located 8 billion light
years away. If our universe is approximately
15 billion years old, when did the quasar
emit the light that we observe?
1.
2.
3.
4.
5.
0/0
15 years ago
7 billion years ago
8 billion years ago
15 billion years ago
23 billion years ago
Cross-Tab Label
Colliding galaxies
• Take notes on the
following
• https://www.youtub
e.com/watch?v=U
QNo1hkcrYU
Imagine that you simultaneously receive the satellite transmission
of two pictures of two people that live on planets orbiting two
different stars. Each image shows the people at their 21st birthday
parties. Consider the following possible interpretations that could
be made from your observations.
Which do you think is the most plausible interpretation?
1. Both people are the same age but at different distances from you.
2. The people are actually different ages but at the same distance
from you.
3. The person that is closer to you is actually the older of the two
people.
4. The person that is farther from you is actually the older of the two
people
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Fifteen years ago, a quasar was observed that
was found to be located 8 billion light years
away. If our universe is approximately 15 billion
years old, when did the quasar emit the light that
we observe?
1.
2.
3.
4.
5.
15 years ago
7 billion years ago
8 billion years ago
15 billion years ago
23 billion years ago
0/0
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Cross-Tab Label
Colliding galaxies
• Take notes on the
following
• https://www.youtube
.com/watch?v=UQN
o1hkcrYU
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