•coming up: the sun (chapterchris/astro115/lectures/lec9.pdfreview of chapter 3! to understand...
TRANSCRIPT
![Page 1: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/1.jpg)
• Summary of Chapter 3: Light
Today
•All of Chapter 4: Spectra & AtomsOptional: Ast. Toolbox 4-2Optional: Stephan-Boltzmann Law
•Coming up: The Sun (Chapter 10)
![Page 2: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/2.jpg)
1. Light Gathering Power: The ability to collect light
2. Resolving Power: The ability to see fine details
3. Magnifying Power: The ability to make objects look bigger
Telescopes have Three Powers
![Page 3: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/3.jpg)
Resolving Power: Seeing Details
Resolving Power (or resolution) is a telescope’s ability to see small details. It is proportional to a telescope’s size (diameter D)
![Page 4: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/4.jpg)
Magnification makes things look larger
However it does not improve resolution (seeing fine details).
![Page 5: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/5.jpg)
The Best Location for a TelescopeFar away from civilization – to avoid light pollution
Text
![Page 6: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/6.jpg)
On a mountaintopMauna Kea, Hawai’i (~14,000 feet elevation)
![Page 7: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/7.jpg)
Hubble Space Telescope
Or in Space…
Space Telescopes avoid the blurring effects of Earth’s atmosphere.
![Page 8: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/8.jpg)
Space Telescopes also allow us to see light blocked by Earth’s atmosphere: infrared, ultraviolet, X-rays & gamma rays.
Spitzer (2003)Fermi Gamma Ray Observatory (2008)
![Page 9: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/9.jpg)
Infrared Light
Visible Light
Andromeda Galaxy
![Page 10: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/10.jpg)
A newer IR image from the “WISE” satellite
![Page 11: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/11.jpg)
X-ray Astronomy
X-rays are high energy light with very short wavelength
They are emitted by very hot gas in the universe.
Chandra X-ray Telescope Chandra Image of Supernova Explosion
![Page 12: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/12.jpg)
The Largest Radio Telescope
Since radio waves pass through Earth’s atmosphere,
we can build radio telescopes on the ground.
The 300-m telescope in Arecibo, Puerto Rico is the
largest in the world.
It can hold 13 football fields!
![Page 13: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/13.jpg)
Review of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with three properties:
! Speed: c = 300,000 km/s ! Frequency (f): number of light waves per second. ! Wavelength (λ): distance. from one peak to the next
!We see different wavelengths as colors ! These are related: c = f x λ
! Many forms of light exist, most invisible to humans: ! Infrared radiation and radio waves have longer
wavelengths than visible ! Ultraviolet, X rays, and gamma rays have shorter
wavelengths ! Visible light occupies only a small portion of the
“elctromagnetic spectrum.”
![Page 14: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/14.jpg)
Chapter 3 Review! Visible light waves are small: their wavelengths (λ) are
measured in nanometers (1 nm = 10-9 m) ! λ=400 nm for violet light and λ=700 nm for red ! Light’s energy depends on its frequency
! Telescopes: gather light, reveal details, and magnify images
! The two main types: ! Reflectors produce images using mirrors, ! Refractors use lenses to focus light
! Light gathering ability depends on the telescope mirrors’s area. ! The area of a circle is: A = π r 2
![Page 15: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/15.jpg)
The Power of StarlightChapter 4
By analyzing the light from a star, we learn about its:
1. Temperature 2. Composition 3. Motion
![Page 16: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/16.jpg)
Red Hot Orange Hot Yellow Hot
Using Light to Measure Temperature
![Page 17: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/17.jpg)
Color and Temperature
Orion
Betelgeuse
Rigel
Stars have different colors,
Rigel is blue
Betelgeuse is red
The different colors of stars are due to their different temperatures.
![Page 18: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/18.jpg)
TemperatureAstronomers use Kelvins (K) to measure temperatures.
Example:
The freezing point of water is:
32 F
0 C
273 K
0 K is Absolute Zero
![Page 19: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/19.jpg)
Challenge Question:
Are you sure? What about at sunset?
The Sun produces light that is not yellow.
What Color is the Sun?
![Page 20: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/20.jpg)
Wavelengths of Light
• Light from any source has a variety of colors.• Q: At which color (or wavelength) does the
source emit the most light?
• To answer this question we use a spectrograph.• A spectrograph produces readout of light intensity
vs. wavelength called a spectrum
![Page 21: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/21.jpg)
The SpectrographA spectrograph uses a prism to
split light up into different wavelengths (=colors!)
![Page 22: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/22.jpg)
Chapter 28 Opener
![Page 23: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/23.jpg)
Modern spectra are recorded digitally as plots of intensity vs.
wavelength
A Spectrum
![Page 24: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/24.jpg)
The Sun emits UV, Visible and Infrared light
Brig
htne
ss
(c) C. Baird, ASTM
Spectrum of the Sun
Wavelength
UV Infrared
Visible
![Page 25: •Coming up: The Sun (Chapterchris/astro115/lectures/lec9.pdfReview of Chapter 3! To understand what’s in space, we must understand light. ! Light is an electro-magnetic wave with](https://reader034.vdocuments.site/reader034/viewer/2022043017/5f39c0bbd48c18507a4f3df8/html5/thumbnails/25.jpg)
Stellar Spectra
• Sun emits more yellow (λ=570 nm) light than any other color.
• We say the “The Sun is yellow” because its spectrum “peaks” in the yellow part.
• We can use this fact to measure the temperature of the Sun, or any other star.