Cosmic Survey History of the Universe

Cosmic SurveyHistory of the Universe

Linda L. SmithElementary Science Resource Specialist

Paulsboro Public SchoolsNASA Educator [email protected]

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.

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

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.

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.

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

How Do We Know?

When we organize light waves in this type of order, we call it the

“Electromagnetic Spectrum” or EMS

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

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

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

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

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

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

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

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

http://imagers.gsfc.nasa.gov/ems/atmosphere.gif

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!

How Do We Know?

• 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

How Do We Know?

• 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

How Do We Know?

• 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

How Do We Know?

• 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

How Do We Know?

• 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.

Size and Scale of the Universe

Image courtesy of The Cosmic Perspective by Bennett, Donahue, Schneider, & Voit; Addison Wesley, 2002

What We Know

M45 – The Pleiades Cluster

X-ray: T. Preibisch Ultraviolet: MSX Visible: AAO

Infrared: IRAS Radio: NVSS

Multi-wavelength Crab Nebula

X-ray: Chandra Ultraviolet: UIT Visible: Palomar

Infrared: 2MASS Radio: VLA

M51 – The Whirlpool Galaxy

X-ray: Chandra Ultraviolet: GALEX Visible: T. & D. Hallas

Infrared: ISO Radio: VLA

How Big?Telescope40 feet long, 12 metersMoon2,000 miles across, 3,200 kilometersSaturn75,000 miles across, 121,000 kilometersSun875,000 miles across, 1,408,000 kilometersPleiades60 trillion miles across, 1 x 1014 KilometersWhirlpool Galaxy600 thousand trillion miles across, 1 x 1018 KilometersHubble Galaxies600 thousand million trillion miles across, 1 x 1021 Kilometers

How Far?Telescope350 miles above Earth’s surface, 560 kilometersMoon250,000 miles, 402,000 kilometersSun93,000,000 miles, 1.5 x 108 kilometersSaturn120,000,000 miles, 1.3 x 109 kilometers (at its closest)Pleiades2,400 trillion miles, 4 x 1016 kilometersWhirlpool Galaxy200 million, trillion miles, 3 x 1020 kilometersHubble Galaxies30 billion trillion miles, 5 x 1020 kilometers

How Old?TelescopeA few years (launched in 1990)Pleiades80 million yearsMoon4.5 Billion yearsSaturn4.5 Billion yearsSun4.5 Billion years Whirlpool Galaxy13 billion yearsHubble Galaxies13 billion years

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.

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

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.

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)

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.

Direction of Galactic Rotation

To C

ente

r of G

alax

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The image is 390 light-years across.

You Are Here

The Milky Way Galaxy is a giant disk of stars 160,000 light-years across and 1,000 light-years thick.

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

The Sun is located at the edge of a spiral arm, 30,000 light-years

from the centerIt takes 250 Million years for the

Sun to complete one orbit

The Milky Way Galaxy

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

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 Universe1.

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ligh

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• 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.

The Universe

Computer Simulation

The observable Universe is 27 Billion

light-years in diameter.

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

If the Sun were the size of this room,

how big would earth be?

The size of a grapefruit

If the Solar System were the size of this room, how big would the Sun be?

A grain of salt

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

If the Solar System were the size of this room, how big would Earth be?

The size of microscopic bacteria(~ 4 microns)

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.

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.

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

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

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

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

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.

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

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.

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.

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!

More Information

• To order Free NASA materials go to:http://epo.sonoma.edu/orderforms/orderformpublic.html

• To find out more about the GALEX mission go to:http://www.galex.caltech.edu/