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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?.
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UNIT 4 Tools of AstronomyUnit 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’t “see” These things are either • Too far away and too dim or • Do not emit visible light
First Thoughts: Making Claims • Describe and/or draw what you might think the room around you would look like: • If you had eyes that could detect heat instead of visible light. • If you had eyes that could see x-rays. • Describe and/or draw what you think the night sky around you would look like: • If you had eyes that could detect heat instead of visible light. • If you had eyes that could see x-rays.
Activity 1: Gathering Evidence From a Scene Key Concepts • A • B Objectives • A • 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 • What is the difference in direct and indirect evidence? • 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 • Which pieces of evidence could you observe directly, and which would require inference? • Is inference always accurate? Explain. • 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, ProximaCenturi, 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 • A • B Objectives • A • B
Describe what part or feature of the image you think you are seeing
Pause and Reflect • How does seeing images of different types of electromagnetic radiation from an object help you understand more about the object?
Pause and Reflect • Would you have recognized the object from just the first image (the radio image)? • 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 • 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
The Sun during extreme solar activity Gamma Ray Images
BLAZAR 3C 273 Chandra (X-ray) Hubble (Optical) (Gamma Ray)
X – ray Images of the Sun SOHO: Solar and Heliospheric Observatory YOHKOHhttp://solar.physics.montana.edu/sxt/
Ultraviolet Radiation (UV-Rays) Objects that strongly emit UV rays UV-Rays provide information about the Interstellar Medium: chemical composition Density 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 Allow us to determine Composition Motion Temperature Physical features • Terrestrial • Keck (10 meter) in HA • Space based • Hubble Space Telescope (HST)
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).
Checking In • How do the different forms of electromagnetic radiation differ from one another? • Name four objects or processes that are better observed using a type of electromagnetic radiation other than visible.
