Transcript UNIT 4 - Rowan County Schools

UNIT 4
Tools of Astronomy
Unit Focus:
Information about the universe
comes to earth through
electromagnetic waves of different
wavelengths
Exploration 1
Observing the Universe
Essential Question 1:
What can different types of
electromagnetic radiation reveal
about astronomical objects?
The Astronomers Challenge
• Humans have only visited 1 body other than earth in
our universe – the moon (1969)
– Lunar soil was gathered and returned to earth for analysis
• Space Probes have landed on 4 other bodies in the
solar system
– Venus (1970)
– Mars (1971)
– 433 Eros – asteroid (2001)
Astronomers cannot simply gather a sample of a star or
galaxy and bring to a laboratory on earth to analyze
What can we gather
from objects in space?
LIGHT
Electromagnetic Radiation
Some things we can “see”
Some things we can’t “see”
These things are either
1. Too far away and too dim or
2. Do not emit visible light
First Thoughts: Making Claims
1. Describe and/or draw what you might think
the room around you would look like:
a. If you had eyes that could detect heat instead of
visible light.
b. If you had eyes that could see x-rays.
2. Describe and/or draw what you think the
night sky around you would look like:
a. If you had eyes that could detect heat instead of
visible light.
b. If you had eyes that could see x-rays.
Activity 1:
Gathering Evidence From a Scene
Key Concepts
1. A
2. B
Objectives
1. A
2. B
1. Read FYI: Evidence and Inference
• Direct Evidence
• Indirect Evidence
• Inference
Examples of Direct Evidence
• Mass of astronomical objects in binary
systems
• Luminosity – total power output of an object
• Flux Density – power received per unit area
per wavelength
Examples of Indirect Evidence
• Existence due to gravitational effects (black
holes, dark matter, dark energy)
• Mass (black holes)
• Distance – Hubble’s Law
Inference
• Explanations for an observation
Example:
Observation: The grass on the schools front lawn
is wet
Inferences:
Checking In
1. What is the difference in direct and indirect
evidence?
2. Describe how astronomers use inference and
electromagnetic radiation to learn about
astronomical objects.
Thoughts on the drawing
• Which car caused the collision?
• In which direction where the cars moving
before the collision?
• Your questions here!!! Develop 2 more Q’s.
• Develop a theory explaining what happened
in the drawing.
• Identify at least 3 pieces
of evidence to support
your theory.
Pause and Reflect
1. Which pieces of evidence could you observe
directly, and which would require inference?
2. Is inference always accurate? Explain.
3. Is direct observation always accurate.
Explain.
The Light-Year (ly)
• The meter is just too small to use to represent astronomical
distances
• We use many units specific to astronomy
– Astronomical unit (AU): average distance between the sun and
the earth 1AU = 149,597,870.7 km
– Light year: the distance light travels in one year
• Express light years in meters and kilometers.
• The closest star to our solar system, Proxima Centuri, is 4.5 ly. How
many kilometers away is it? How long would it take humans to get
there if traveling at 57,600 km/h (This is the speed of the New
Horizons space craft that was launched in 2006 and is heading toward
Pluto)
– Parsec (pc): distance corresponding to the parallax of one
second. (we’ll discuss this later)
1pc = 3.26 ly
Activity 2 What does
Electromagnetic Radiation Tell Us?
• Key Concepts
1. A
2. B
Objectives
1. A
2. B
Describe what part or feature of
the image you think you are seeing
Pause and Reflect
1. How does seeing images of different types of
electromagnetic radiation from an object
help you understand more about the object?
Can you guess what I am?
My radio emission is imaged below
I look a little different in X-ray
Here I am in optical
Pause and Reflect
1. Would you have recognized the object from
just the first image (the radio image)?
2. Which type of electromagnetic radiation
shows the object as your are accustomed to
seeing it?
The Crab Nebula (M1)
• The crab nebula is a supernova remnant (SNR)
• A SNR is the expanding shell of gas that is
ejected into space after a massive star reaches
the end of it’s life and explodes.
• The Crab nebula exploded in 1054 AD. It was
observed by the Chinese and Arabs and was
known to the Chinese as the “guest star”
For each image,
describe what features you can see that
are not apparent in the other images.
Pause and Reflect
1. How does seeing images
of different types of
electromagnetic radiation
from an astronomical
object help you
understand more about
the object?
How the Crab nebula got it’s name
• Drawing of the Crab
Nebula by William
Parsons, the Third Earl
of Rosse.
• This drawing gave rise
to the name "Crab
Nebula". It was created
using the 36-inch
reflector at Birr Castle
about 1844.
Activity 3: Discovering
the Multi-wavelength Universe
Over the past few decades science organizations
around the world have invested great
amounts of money in building major
telescopes to observe various forms of
electromagnetic radiation
STEP 1
• Read FYI: Observing Different types of
Electromagnetic Radiation
X-Rays and Gamma (γ) Rays
• Highest-energy forms of
electromagnetic
radiation
• Produced by
– material that is heated
to millions of degrees
– often the result of
cosmic explosions
– high speed collisions
– or material moving at
extremely high speeds
• Led to the discovery of
black holes
• Added to our
understanding of SN,
white dwarfs, and
pulsars
• Observations of x and γ
rays of the sun allow
astronomers to study
the hottest regions of
the sun
Gamma Ray Images
• The Sun during extreme solar activity
BLAZAR 3C 273
Chandra (X-ray)
(Gamma Ray)
Hubble (Optical)
X – ray Images of the Sun
SOHO:
Solar and Heliospheric Observatory
YOHKOH
http://solar.physics.montana.edu/sxt/
Ultraviolet Radiation (UV-Rays)
Objects that strongly
emit UV rays
UV-Rays provide information
about the Interstellar
Medium:
•
•
•
•
•
•
1. chemical composition
2. Density
3. Temperature
Very young massive stars
Some very old stars
Bright nebulae
Young white dwarf stars
Active galaxies
Quasars
UV images of the Sun
SOHO UV image
IUE – International Ultraviolet
Explorer Satellite
Ultraviolet Images
UV image of Jupiter’s Moon Io
during a volcanic eruption
Visible Image of Io
UV image of M101
• A spiral galaxy located
about 16 million light
years from the Earth in
the constellation Ursa
Major (the Great Bear).
• The bright sections of
the image reveals
regions where new stars
are forming at a rapid
rate,"
Visible light
Optical telescopes
• Terrestrial
– Keck (10 meter) in HA
• Space based
– Hubble Space Telescope (HST)
Allow us to determine
• Composition
• Motion
• Temperature
• Physical features
Infrared (IR)
•
Image: Spitzer Space Telescope
NASA's newly named Spitzer Space Telescope has
captured dazzling images of a dusty, spiral galaxy; a
planet-forming disc; a glowing, stellar nursery and a
young, buried star, demonstrating the power of its
infrared eyes to spy hidden objects.
Top left: The dusty, star-studded arms of M81, a nearby
spiral galaxy similar to our own, are illuminated in
unprecedented detail. The image reveals Spitzer's ability
to explore regions invisible in optical light.
Top right: A massive disc of dusty debris encircles a
nearby star called Fomalhaut. Such discs are remnants
of planetary construction; our own planet is believed to
have formed out of a similar disc.
Bottom left: Resembling a flaming creature on the run,
this image exposes the hidden interior of a dark and
dusty cloud in the emission nebula IC 1396. Young stars
previously obscured by dust can be seen here for the
first time.
Bottom right: This Spitzer image transforms a dark cloud
into a silky translucent veil, revealing the stellar winds
from an otherwise hidden newborn star called HH46-IR.
Spitzer's remarkable capacity to peer through cosmic
dust allowed it to unveil this never-before-seen star.
Microwave
WMAP:
Wilkinson Microwave
Anisotropy Probe
– NASA's Wilkinson Microwave Anisotropy
Probe (WMAP) has mapped the Cosmic
Microwave Background (CMB) radiation (the
oldest light in the universe) and produced the
first fine-resolution full-sky map of the
microwave sky
– WMAP definitively determined the age of the
universe to be 13.73 billion years old to within
1% (0.12 billion years) -as recognized in the
Guinness Book of World Records!
– determination that ordinary atoms (also called
baryons) make up only 4.6% of the universe
(to within 0.1%)
– dark matter (not made up of atoms) make up
23.3% (to within 1.3%)
– dark energy makes up 72.1% of the universe
(to within 1.5%), causing the expansion rate of
the universe to speed up. Science Magazine
2003, "Breakthrough of the Year" article
Radio Waves (RF)
Radio waves
• Have very low energy
• Used to gather information
about:
– Supernova
– Quasars/blazars (activie
galaxies)
– Pulsars
– The interstellar medium
– The big bang
Radio
The Whirlpool Galaxy (M51)
This radio images shows that
the radio emission from the
galaxy’s cold hydrogen gas
(blue) extends well beyond
the optical light emitted by
its stars
(Credit: NRAO/AUI, J. Uson).
Guess what I am…
Checking In
1. How do the different forms of
electromagnetic radiation differ from one
another?
2. Name four objects or processes that are
better observed using a type of
electromagnetic radiation other than visible.
M17 – an emission nebula
M45 – an open star cluster
the Pleiades
M104 – a spiral galaxy
Sombrero galaxy
30 Doradus – an emission nebula
Tarantula Nebula
STEP 3
1. Go to the link under Investigating Tools of
Astronomy: Exploration 1 Activity 3 on the IA
Web Site, where you will encounter images
and information about numerous
observations of these objects
2. Find images and descriptions for your
objects.
– APOD: Astronomy Picture of the Day is a great
place to search for information about most
astronomical objects
STEP 4
• Create a small poster or other type of display to
show your object as it appears in as many types
of electromagnetic radiation as you can find on
the Web.
• Write a description to accompany your display
that includes
– The type of object and at least 2 important
characteristics such as distance, age, or distinguishing
features
– Features of the object that are evident from one type
of electromagnetic radiation but not from others
– Questions you have about the object
STEP 5
• Read FYI: Astronomical Objects in Different
Types of Electromagnetic Radiation.
Centaurus A
• When observed using certain types of EM is
the largest object in the sky
• In order to understand more about Centaurus
A astronomers examine it using each type of
electromagnetic radiation
• They interpret the evidence that each type of
EM radiation provides as they try to
determine the nature and origin.
Centaurus A - Optical
Centaurus A - Radio
Centaurus A - Infrared
Centaurus A – X-ray
Centaurus A - UV
Checking In
1. For each type of electromagnetic radiation
(x-ray, UV, visible, IR, and radio), describe
features of processes that are observable
using that type of radiation.
2. How do observations using multiple types of
radiation tell a bigger story than just one
type can?