Stars and Galaxies

Stars and Galaxies

Stars Stars and and Galaxies Galaxies Created by the Lunar and Planetary Institute For Educational Use Only LPI is not responsible for the ways in which this powerpoint may be used or altered. Space Science for Middle School at HCDE February 20, 2009 Image at

Welcome! Welcome! Please complete the pre-assessment Its for usits not about you Please let us know how much YOU know, not how much your friends sitting next to you know What What are are we

we going going to to cover? cover? Our Place in the Universe The Electromagnetic Spectrum Classifying Stars Classifying Galaxies History of the Universe First First up up

Our Place in the Universe What is our Universe made of? How big are things? How do we know? How far away? What What is is our our Universe Universe made made of?

of? What was in your drawing? Stars and planets Gas and dust Organized into star clusters Organized into nebulae

Organized into galaxies Other things: Black holes Dark matter Dark energy Image from Activity!!

Activity!! Use the Venn diagrams to place the stickers where does everything go? After youre finished, lets discuss Examining Examining the the Components Components Stars Gas and dust (Nebulae)

Star clusters Galaxies Different Different types types of of stars stars Image from

Types Types of of Stars Stars Big Small Red Blue Yellow In groups Alone More later

What What is is aa star star cluster? cluster? stars formed together at same time stars may be gravitationally bound together two types: open (galactic) and globular

Image at Open Open Clusters Clusters dozens to thousands of stars young stars! only a few million years old may still be surrounded by nebula from which they formed

located in the spiral arms of a galaxy example: Pleiades Image at More More open open star star clusters clusters

Image from Globular Globular Clusters Clusters

millions to hundreds of millions of stars old! 6 to 13 billion years mostly red giants and dwarfs stars are clumped closely together, especially near the center of the cluster (densely) surround our disk as a halo Image at What

What is is aa nebula? nebula? A cloud in space Made of gas and dust Can have stars inside Most of the ones we see are inside our Milky Way

Galaxy Different types Orion image at Large, Large, massive, massive, bright bright nebulae nebulae Emission Nebula The hot gas is emitting light

Orion image at Colder, Colder, darker darker nebulae nebulae Dark dust blocking the hot gas behind it NOAO/AURA/NSF Image from

Leftovers Leftovers from from an an Explosion Explosion Supernova remnant (smaller, less gas) Image at What What is is aa galaxy?

galaxy? A large group of stars outside of our own Milky Way Made of billions to trillions of stars Also may have gas and dust Spiral, or elliptical, or irregular shaped

Image at Spiral Spiral galaxy--Andromeda galaxy--Andromeda NOAO/AURA/NSF Images at and Elliptical Elliptical Galaxies Galaxies

Images at and Irregular Irregular Galaxies Galaxies NASA and NOAO/AURA/NSF Images at , , and Our

Our Galaxy: Galaxy: the the Milky Milky Way Way has about 200 billion stars, and lots of gas and dust is a barred-spiral (we think) about 100,000 light-years wide our Sun is halfway to the edge, revolving at half a million miles per hour around the

center of the Galaxy takes our Solar System about 200 million years to revolve once around our galaxy The The Milky Milky Way Way Image at Mapping Mapping the

the Milky Milky Way Way How do we know what our Galaxy looks like? We can see stars star clusters nebulae Galaxies Lets try to Map our Galaxy

Measuring Measuring Distances Distances Parallax (lets model it) As Earth orbits the Sun, we see nearby stars move relative to more distant stars How many degrees did the plate move, relative to the background?

Can you calculate the distance to the plate? Sine of the parallax (angle) x Earths distance to the Sun = Distance to the star The angles involved for strellar observations are very small and difficult to measure. Proxima Centauri, has a parallax of 0.77 arcsec. This angle is approximately the angle subtended by an object about 2 centimeters in diameter located about 5.3 kilometers away.

Measuring Measuring Distances Distances What is a Light Year? A light year is the distance light travels in a year. Light moves at a velocity of about 300,000 kilometers (km) each second; how far would it move in a year? About 10 trillion km (or about 6 trillion miles).

Why do we use light years? Show me how far 5 centimeters is. Now show me 50 centimeters. Now tell me (without thinking about it, or calculating it in meters) how far 500 centemeters is. 2000? 20,000? We need numbers that make sense to us in relationship to objects; we

scale up and use meters and kilometers for large numbers. Time Time for for aa Break! Break! Next Next Up Up Our Place in the Universe The Electromagnetic Spectrum Classifying Stars Classifying Galaxies History of the Universe

Lets Lets check check your your knowledge knowledge Please draw an electromagnetic spectrum on a sheet of paper, and label the parts. You can work in groups. Radiation Radiation

There are lots of types of light (radiation), including visible and invisible Electromagnetic spectrum . Lets Lets Observe Observe A A Spectrum Spectrum

What will the spectrum look like with a red filter in front of your eyes? A blue filter? Hypothesize and test your hypothesis. Now lets examine the invisible parts using our cell phones and a solar cell. There are different types of spectra Continuous Emission or Bright Line (from ionized gas, like a nebula or a neon sign)

Absorption or dark line (from stars) Illustration at Radiation Radiation All stars emit radiation Radio, infrared, visible, ultraviolet, x-ray and even some gamma rays

Most sunlight is yellow-green visible light or close to it The Sun at X-ray wavelengths Image at ience/know_l1/sun.html Image and info at Using Using aa Stars

Stars Spectrum Spectrum We can use a stars spectrum to classify it. NOAO/AURA/NSF image at Stellar Stellar Evolution Evolution Time Time to to Create

Create aa Stellar Stellar Graph Graph Everyone will receive several stars Place them on the large paper, according to their color and their brightness This is a version of the Hertzsprung-Russell diagram. Hertzsprung-Russell Hertzsprung-Russell Diagram Diagram

Images from and Young Young stars stars form form in in nebulae

nebulae from fromSmall Small Magellanic Magellanic Cloud Cloud Image at Star-forming region in the Large Magellanic Cloud:

Orion image at Interstellar Interstellar eggs eggs Movie at Our Our Sun Sun is is aa Regular/ Regular/ Small

Small Star Star On the Main Sequence Image at In In aa few few Billion Billion years years Red Red Giant

Giant Image at Our Our Suns Suns Habitable Habitable Zone Zone Billions of years ago, things may have been different

The Sun was cooler (by up to 30%!) Earths atmosphere was different (thicker, carbon dioxide) Conditions will be different in the future

By many accounts, increases in the Suns temperature will make Earth uninhabitable in 1 billion years or less These changes will also affect other planets Mars? Animation at http://www.nasa .gov/97994main _BHabitableZon e.MPG By

By 55 billion billion years years White White Dwarf Dwarf Small, but very hot Image at Image at

Image at Massive Massive Stars Stars are are different different On the Main Sequence but not for long

Image from BetelgeuseRed BetelgeuseRed Supergiant Supergiant Image from SupernovaMassive SupernovaMassive Star Star Explodes

Explodes Images at Neutron Neutron Star Star or or Pulsar Pulsar

Image at Black Black Hole Hole Image at Classifying Classifying Galaxies Galaxies Galaxies

Galaxies come in different sizes (dwarf, large, giant) come in different shapes and classifications Spirals Ellipticals Lenticulars Irregulars are fairly close together, relative to their

sizes Spiral Spiral Galaxies Galaxies have flat disk, spiral arms, central bulge, and a surrounding halo some have a barred bulge are fairly large (no dwarf spirals) have lots of gas and dust and younger stars in their arms, but older stars and little gas or dust in their halos and central bulges

Galaxies Galaxies Image at Spiral Spiral galaxy--Andromeda galaxy--Andromeda NOAO/AURA/NSF Images at and

Spiral Spiral Galaxy Galaxy on on Edge Edge Image at Image at

Elliptical Elliptical galaxies galaxies range from spherical to football shaped range from very small to giant have very little gas or dust mostly old stars similar to the central bulge of a spiral galaxy Elliptical Elliptical Galaxies

Galaxies Images at and Lenticular Lenticular have a disk but no arms have little or no excess gas and dust Image at

Irregular Irregular Galaxies Galaxies any galaxy that isnt a Spiral, Elliptical, or Lenticular usually have lots of gas and dust and young stars may have a distorted shape from interaction with another galaxy

Irregular Irregular Galaxies Galaxies NASA and NOAO/AURA/NSF Images at results/50/ , , and Collisions! Collisions! We now think that galaxies in groups and clusters often collide

The Milky Way is moving at 300,000 mph toward the Andromeda Galaxy They may collide in about 5 billion years Stars dont usually collide New orbits, gas piles up to form new stars Interacting Interacting Image from the the Antennae

Antennae or or Mice Mice Information at The occasional results of two galaxies colliding: ringed galaxies Images from and

Various Various galaxies galaxies (can (can you you identify identify types?) types?) Image at

Supermassive Supermassive black black holes holes almost every medium to large galaxy weve check has a supermassive black hole at the center the larger the galaxy, the more massive the black hole we dont know which comes first, the galaxy or the black hole we think that these black holes are responsible for some of the galaxies with jets and lobes which give off radio waves, x-rays, etc.

Active Active galaxy galaxy Image at at at the the center center of

of aa large large galaxy galaxy Image at and Galaxy Galaxy Clusters Clusters the Local Group

includes the Milky Way, the Andromeda, and over 30 other smaller galaxies the Virgo Cluster hundreds to thousands of galaxies, 60 million lightyears away

giant elliptical at center, formed by galactic cannibalism the Local Group is falling toward the Virgo Cluster at 60 to 250 miles per second! Coma Coma Cluster Cluster Image at Superclusters! Superclusters!

clusters are bound together in larger structures, called superclusters these superclusters have been mapped, and are grouped into long strings 300 million to a billion light-years long 100 to 300 million light-years wide and only 10 to 30 million light-years thick

in between these strings are huge voids of galaxies, although some astronomers may have detected hot gas Evolution Evolution of of Galaxies Galaxies Image at Origin of the Universe Big Bang Dominant scientific theory about the origin of

the universe Occurred ~13.7 billion years ago What is the Big Bang? How do we know? What What is is the the Big Big Bang? Bang?

Infinitely dense point not governed by our physical laws or time All matter and energy contained in one point Image from Building

Building aa Universe Universe Instantaneous filling of space with all matter History History of of the the Universe Universe 10-43 seconds - gravity separates from other forces

10-35 to 10-32 seconds - fundamental particles - quarks and electrons 10-6 seconds - quarks combine into protons and neutrons 1 second - electromagnetic and weak nuclear forces separate 3 minutes - protons and neutrons combine into atomic nuclei 105 years - electrons join nuclei to make atoms; light is emitted 105-109 years - matter collapses into clouds, making galaxies and stars Orion Nebula - History History of

of the the Universe Universe Image from Later Later History History Image at Big

Big Bang Bang Theory Theory In 1915, Albert Einstein concluded that the universe could not be static based on his recently-discovered theory of relativity and added a "cosmological constant" to the theory of relativity because astronomers assured him that the universe was static

Aleksandr Friedmann and Abbe George LeMaitre are credited with developing the basics of the Big Bang model between 1922 and 1927; their calculations suggested that universe is expanding, not static. Years later, Einstein called his cosmological constant the biggest mistake of his career Image at

Expanding Expanding Universe Universe In 1929, Edwin Hubble showed that most galaxies are red-shifted (moving away from us), and that a galaxys velocity is proportional to its distance (galaxies that are twice as far from us move twice as fast) Image from

Hubbles Hubbles Evidence Evidence Doppler shifting - wavelength emitted by something moving away from us is shifted to a lower frequency Sound of a fire truck siren - pitch of the siren is higher as the fire truck moves towards you, and lower as it moves away from you

Visible wavelengths emitted by objects moving away from us are shifted towards the red part of the visible spectrum The faster they move away from us, the more they are redshifted. Thus, redshift is a reasonable way to measure the speed of an object.

When we observe the redshift of galaxies, almost every galaxy appears to be moving away from us the Universe is expanding. Predictions Predictions for for the the Big Big Bang Bang Model Model The expansion of the Universe

Edwin Hubble's 1929 observation that galaxies were generally receding from us provided the first clue that the Big Bang theory might be right. The abundance of the light elements H, He, Li The Big Bang theory predicts that these light elements should have been fused from protons and neutrons in the first few minutes after the Big Bang.

The cosmic microwave background (CMB) radiation The early universe should have been very hot. The cosmic microwave background radiation is the remnant heat leftover from the Big Bang. Evidence Evidence for for Big Big Bang Bang

Red shift - as light from distant galaxies approach earth there is an increase of space between earth and the galaxy, which leads to wavelengths being stretched In 1964, Arno Penzias and Robert Wilson, discovered a noise of extraterrestrial origin that came from all directions at once - radiation left over from the Big Bang In June 1995, scientists detected helium in the far reaches of the universe consistent with an important aspect of the Big Bang theory that a mixture of

hydrogen (75%) and helium (25%) was created at the beginning of the universe When When Did Did the the Universe Universe Form? Form? Cosmic background radiation temperature on celestial sphere

~13.7 billion years ago How do we know? Spreading (Red Shift) know distances, rates of retreat, relative positions Pervasive background radiation of 2.7C above absolute zero - afterglow

of the Big Bang Feedback, Feedback, Questions Questions Reach us online at For more information, contact Christine Shupla Lunar and Planetary Institute 3600 Bay Area Blvd Houston, TX 77058 (281) 486-2135 [email protected]

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