1. Cosmic Survey History of the Universe
Linda L. Smith
Elementary Science Resource Specialist
Paulsboro Public Schools
NASA Educator Ambassador

2. How Do We Know
Scientists study how light and other energies interacts with different things.
From those observations they know that light, and any other kind of energy travels in waves.

3. How Do We Know
Scientists studied those waves and noticed that they had rules.
They noticed that in any one type of energy, the space between the top of one loop to the top of the next loop was always the same.
They called that space wavelength

4. How Do We Know
Scientist also noticed that every different kind of energy had a different wavelength
Because of this, scientist now had a way to tell different kinds of energy apart.

5. How Do We Know
Because each wavelength was exactly the same as the next, scientist discovered that each kind of energy moved a different amount of waves through a specific space in a specific time.
Because of this, scientist now discovered you could tell what kind of energy you had by counting the amount of waves that went by in a set amount of time. They called this measurement frequency.

6. What does the EMS tell us? (Electromagnetic Spectrum)
Transports energy
Electric and magnetic fields oscillate: that’s the “wave”
Moves at speed of light, 3 x 108 m/s
Wavelength, frequency, energy all related
Type of radiation (usually) depends on energy/temperature of object

7. How Do We Know?
When we organize light waves in this type of order, we call it the “Electromagnetic Spectrum” or EMS

8. How Do We Know
Radio waves are energy that has long wavelengths and small frequencies.
They are the kind of energy we attach radio signals to broadcast them.
Stars and gasses in space also emit radio waves

9. How Do We Know
Microwaves have a shorter wavelength, about the size of a honeybee.
Cell phones and microwave ovens produce microwaves
Gasses that are collapsing into stars in space also produce microwaves

10. How Do We Know
Infrared energy has an even shorter wavelength, about the size of the head of a pin.
They are easily absorbed into molecules, heating them up, like our french fries at MacDonald's
The dust between the stars also gives off infrared energy

11. How Do We Know
Visible light rays are even shorter, about the size of a protozoan.
Visible light is the kind of energy that bounces off of me, into your eyes, and allows you to see me.
Anything you can see with your eyes is in the visible light range

12. How Do We Know
Ultraviolet wavelengths are even smaller, about the size of a molecule. That makes their frequencies very high.
A lot of waves can fit in a space, so they have a lot of energy
The sun and other stars produce ultraviolet energy
Our skin is a detector of ultraviolet energy

13. How Do We Know
X-rays are even smaller than Ultraviolet waves, about the size of an atom,
so they have even more energy than ultraviolet rays
Doctors use x-rays to look at your bones.
Hot gases in space also emit x-rays

14. How Do We Know
Gamma rays are even smaller than x-rays, about the size of a nucleus of an atom. They have even more energy.
Radioactive materials, and particle accelerators make gamma rays
The biggest producer of gamma rays is our universe

15. How Do We Know
We started to make telescopes that would detect different kinds of frequencies
Some telescopes can detect visual light energy
Some can detect X-ray energy
Some can detect radio energy
Putting all this information together helps us to understand what’s going on in our universe

16. To see gamma rays, X-rays, most UV and some IR you must go to space
Only visible, radio and some IR and UV gets through the air!
To see gamma rays, X-rays, most UV and some IR you must go to space

17. Hubble Space Telescope
How Do We Know?
Hubble Space Telescope
Is probably the most famous of Telescopes
Three cameras, two spectrographs, and fine guidance sensors
Produces high resolution images of astronomical objects
Its images are 10 times better than the best telescope on earth.
Takes pictures of small areas in great detail

18. How Do We Know? GALEX Space Telescope
Relatively small satellite. It is just about six feet tall and as wide as your outstretched arms.
The two mirrors of the GALEX telescope are just a half meter (20 inches) across
Acts like a digital camera that takes pictures in the ultraviolet range of light waves
Takes broad far away shots of the sky

19. How Do We Know? GALEX Space Telescope
Orbits the earth once every 98 minutes
Takes pictures that are 2 moons wide
Has special mirrors that curve the light.
Ordinary telescopes would get images that looked like comets from such a large scan of the sky. GALEX’s mirrors change that kind of image into a flat picture
In addition to visible light GALEX has detectors that can read ultra violet light

20. How Do We Know? GALEX Space Telescope
Hubble Telescope takes very detailed pictures of a very small section of the sky
GALEX takes very large pictures of very large pieces of the sky
It’s kind of like Hubble taking close up pictures and GALEX taking landscape picture

21. GALEX & Hubble Space Telescopes Working Together
How Do We Know?
GALEX & Hubble Space Telescopes Working Together
Scientists take pictures from Hubble and Galax and compare and contrast the data from both telescopes
The analysis of these images and images from many more telescopes are the basis of what we know about the Universe today.

22. Size and Scale of the Universe
What We Know
Size and Scale of the Universe
Image courtesy of The Cosmic Perspective by Bennett, Donahue, Schneider, & Voit; Addison Wesley, 2002

23. M45 – The Pleiades Cluster
X-ray: T. Preibisch
Ultraviolet: MSX
Visible: AAO
Infrared: IRAS
Radio: NVSS

24. Multi-wavelength Crab Nebula
X-ray: Chandra
Ultraviolet: UIT
Visible: Palomar
Infrared: 2MASS
Radio: VLA

25. M51 – The Whirlpool Galaxy
X-ray: Chandra
Ultraviolet: GALEX
Visible: T. & D. Hallas
Infrared: ISO
Radio: VLA

27. Sample Universal Objects

28. How Big? Telescope 40 feet long, 12 meters Moon
2,000 miles across, 3,200 kilometers
Saturn
75,000 miles across, 121,000 kilometers
Sun
875,000 miles across, 1,408,000 kilometers
Pleiades
60 trillion miles across, 1 x 1014 Kilometers
Whirlpool Galaxy
600 thousand trillion miles across, 1 x 1018 Kilometers
Hubble Galaxies
600 thousand million trillion miles across, 1 x 1021 Kilometers

29. How Far? Telescope 350 miles above Earth’s surface, 560 kilometers
Moon
250,000 miles, 402,000 kilometers
Sun
93,000,000 miles, 1.5 x 108 kilometers
Saturn
120,000,000 miles, 1.3 x 109 kilometers (at its closest)
Pleiades
2,400 trillion miles, 4 x 1016 kilometers
Whirlpool Galaxy
200 million, trillion miles, 3 x 1020 kilometers
Hubble Galaxies
30 billion trillion miles, 5 x 1020 kilometers

30. How Old? Telescope A few years (launched in 1990) Pleiades
80 million years
Moon
4.5 Billion years
Saturn
Sun
Whirlpool Galaxy
13 billion years
Hubble Galaxies

32. Earth Planet where we all live Comprised primarily of rock
Spherical in shape
12,700 km in diameter
It would take 17 days to circumnavigate the globe driving a car at 100 km/hr
At the speed of light, it would take 0.13 seconds to go all the way around Earth.

33. Sun Star that Earth orbits
Composed primarily of hydrogen and helium gas
Uses nuclear fusion in its core to generate heat and light to allow itself to resist the crushing weight of its own mass
Spherical in shape
1.39 Million km in diameter

34. Earth & Sun The Sun’s diameter is 109 times greater than that of Earth
Over 1 million Earths would fit inside the Sun’s volume
Earth orbits the Sun at an average distance of 150 million kilometers. This distance is called an Astronomical Unit (AU)
It would take 11,780 Earths lined up side to side to bridge the 1 AU between Earth and Sun.

35. The Solar System
8.5 planets, thousands and thousands of planetoids and asteroids, billions of comets and meteoroids
Mostly distributed in a disk about the Sun
Sun blows a constant wind of charged gas into interplanetary space, called the Solar Wind
Boundary between Solar Wind and interstellar space at 100 AU from the Sun (200 AU diameter)

36. The Solar Neighborhood
The region of the Galaxy within about 32.6 light-years of the Sun (65 light-years diameter) is considered its neighborhood.
Here stars move generally with the Sun in its orbit around the center of the Galaxy
This region is inside a large bubble of hot interstellar gas called the Local Bubble. Here the gas temperature is about 1 million degrees Kelvin and the density is 1000 times less than average interstellar space.
To Center of Galaxy
The image is 390 light-years across.
Direction of Galactic Rotation

37. The Milky Way Galaxy You Are Here
The Milky Way Galaxy is a giant disk of stars 160,000 light-years across and 1,000 light-years thick.
The Sun is located at the edge of a spiral arm, 30,000 light-years from the center
It takes 250 Million years for the Sun to complete one orbit
You Are Here
There are over 100 Billion stars in the Milky Way
The Spiral arms are only 5% more dense than average, and are the locations of new star formation

38. The Local Group
Contains 3 large spiral galaxies--Milky Way, Andromeda (M31), and Triangulum (M33)—plus a few dozen dwarf galaxies with elliptical or irregular shapes.
Gravitationally bound together—orbiting about a common center of mass
Ellipsoidal in shape
About 6.5 million light-years in diameter

39. The Local Supercluster
A cluster of many groups and clusters of galaxies
Largest cluster is the Virgo cluster containing over a thousand galaxies.
Clusters and groups of galaxies are gravitationally bound together, however the clusters and groups spread away from each other as the Universe expands.
The Local Supercluster gets bigger with time
It has a flattened shape
The Local Group is on the edge of the majority of galaxies
The Local Supercluster is about 130 Million light-years across
The Local Supercluster

40. The Universe
1.3 Billion light-years
Surveys of galaxies reveal a web-like or honeycomb structure to the Universe
Great walls and filaments of matter surrounding voids containing no galaxies
Probably 100 Billion galaxies in the Universe
The plane of the Milky Way Galaxy obscures our view of what lies beyond. This creates the wedge-shaped gaps in all-sky galaxy surveys such as those shown here.

41. The observable Universe is 27 Billion light-years in diameter.
The Universe
The observable Universe is 27 Billion light-years in diameter.
Computer Simulation

42. Zoom out and make the Entire Visible Universe (27 billion light years across) the size of this room. How large would the Local Group be?
The size of candy

43. If the Sun were the size of this room, how big would earth be?
The size of a grapefruit

44. If the Solar System were the size of this room, how big would the Sun be?
A grain of salt

45. If the Solar System were the size of this room, how big would The orbit of Earth around the Sun be?
The outside edge of a CD

46. The size of microscopic bacteria
If the Solar System were the size of this room, how big would Earth be?
The size of microscopic bacteria
(~ 4 microns)

47. Zoom out and make the Sun’s Neighborhood (2 Astronomical Units) (300 million kilometers) the size of this room. How large would the Solar System be?
A grain of salt.

48. Zoom out and make the Sun’s Neighborhood (65 light years across) the size of this room. How large would the Solar System be?
A grain of salt.

49. Zoom out and make the Milky Way Galaxy (160,000 light years across) the size of this room. How large would the Solar System be?
A peppercorn

50. Zoom out and make the Local Group of Galaxies (6
Zoom out and make the Local Group of Galaxies (6.5 million light years across) the size of this room. How large would the Milky Way Galaxy be?
A large Pizza

51. The size of a basketball
Zoom out and make the Local Super Cluster of Galaxies (130 million light years across) the size of this room. How large would the Local group be?
The size of a basketball

52. The size of a Chip’s Ahoy Cookie
Zoom out and make the Entire Visible Universe (27 billion light years across) the size of this room. How large would the Local Super Cluster be?
The size of a Chip’s Ahoy Cookie

53. We Want to Know More
Scientists believe we can learn more about how the universe came to be by studying Gamma Ray bursts in more detail.

54. Gamma Ray Bursts
Gamma Ray Bursts (GRB’s) are short bursts of Gamma Ray Photons
Gamma Rays are the highest energy, shortest wavelengths radiation we can detect
Photons are the smallest unit of electromagnetic energy we can detect

55. Gamma Ray Bursts
Because they are so fast and small they are hard to record, or to trace back to their origin
Scientists believe that understanding these phenomenon will help us understand the origins of our universe.

56. Studying Gamma Rays
Lasting anywhere from a few milliseconds to several minutes, gamma-ray bursts shine hundreds of times brighter than a typical supernova and about a million trillion times as bright as the Sun,
They are briefly the brightest source of cosmic gamma-ray photons in the observable universe
GRBs are detected roughly once per day from wholly random directions of the sky.

57. Studying Gamma Ray Bursts
GRB’s were discovered accidentally in the late 1960s
U.S. military satellites were launched to look for Soviet nuclear testing in violation of the nuclear test ban treaty.
These satellites carried gamma ray detectors because a nuclear explosion produces gamma rays.
They found thousands of GRB’s, but they didn’t come from Russia, they came from outer space!

58. More Information
To order Free NASA materials go to:
To find out more about the GALEX mission go to: