ASTRONOMY

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ASTRONOMYSOLAR SYSTEM

There are 8 planets and a dwarf planet. The Sun is the center of our solar system:

MERCURY; VENUS; EARTH; MARS; JUPITER;

SATURN; URANUS; NEPTUNE; PLUTO

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MERCURY• Smallest and fastest planet• Orbit is 88 days• Surface is rocky and covered with craters• Has no moon

VENUS *Smaller than the Earth• *Wrapped in bright clouds

(greenhouse effect)• Hottest Planet ; Temperatures 4640 C to

4800 C• Air is poisonous to humans; contains

• High pressure• No moon• Composition: Mostly rock(Terrestrial)

•The Earth is 93 million miles (150 million km)

• The different layers of the Earth are: Crust, Mantle, Core

• Orbits the Sun in 365 days (= 1 year)• Rotates in 24 hours (= 1 day)• One moon

LUNATHE EARTH’S MOON

• Dry, dusty land, flat plains, and craters• Earth’s gravity keepsthe moon from going in a straight

line• The light of the moon is the

reflection of the sun’s light• The dark side of the moon is the

Earth’s shadow

PHASES OF THE MOON

• We always see the same side of the moon• Revolution (orbit around the earth) is 27.3

days = 1 month• The positions of the moon, sun, and Earth

determine the phases of the moon

ECLIPSES

• A lunar eclipse happens when Earth comes between the sun and the moon and the shadow of Earth falls on the moon• A solar eclipse happens when the

moon comes between Earth and the sun and the shadow of the moon falls on part of Earth

• Rocky and shaped by running water • Looks red because the soil is rich in rust (iron oxide) • Same rotation as Earth (day)• Revolution is twice as long as Earth (687

earth days)• Has two small moons• Mons Olympus is a volcano, 16 miles high

JUPITER• A giant gas ball• The planet of storms• The Great Red Spot is a storm that never changes and it is as big as 3 Earths• Jupiter’s atmosphere consists of hydrogen,

helium, some ammonia, methane, and H2O• Temperature of its interior can be 30,0000C• High winds (540 km/h)• Distance from sun 5,2 AU• Rotation: 9h, 55 min• Revolution: 11 years, 314 days

JUPITER’S MOONS• Europa, Ganymede, Callisto, and Io are Jupiter’s largest

moons• Ganymede is the largest moon in the solar system

List of all Jupiter Moons (63):

1. Metis 2. Adrastea 3. Amalthea 4. Thebe 6. Europa 7. Ganymede 8. Callisto 9. Themisto 10. Leda 11. Himalia 12. Lysithea 13. Elara 14. S/2000 15. Carpo 16. S/2003 17. Euporie 18. S/2003 19. S/2003 20. Thelxinoe 21. Euanthe 22. Helike 23. Orthosie 24. 25. S/2003 26. Ananke 27. Praxidike 28. Harpalyke 29. Hermippe 30. Thyone 31. Mneme 32. S/2003 33. Aitne 34. Kale 35. Taygete 36. S/2003 37. Chaldene 38. S/2003 39. S/2003 40. S/2003 41. Erinome 42. Aoede 43. Kallichore 44.

Kalyke 45. Eurydome 46. S/2003 47. Pasithee 48. Cyllene 49. Eukelade 50. S/2003 51. Hegemone 52. Arche 53. Carme 54. Isonoe 55. S/2003 56. S/2003 57. Pasiphae 58. Callirrhoe 59. Sinope 60. Sponde

61. Autonoe 62. Megaclite 63. S/2003

SATURN• 800 times bigger than the Earth• Many moons (more than 53)• Titan is the largest moon of Saturn• Has rings

Major moons: Distance Radius Mass Satellite (000 km) (km) (kg) Discoverer Date --------- -------- ------ ------- ---------- ----- Pan 134 10 ? Showalter 1990 Atlas 138 14 ? Terrile 1980 Prometheus 139 46 2.70e17 Collins 1980 Pandora 142 46 2.20e17 Collins 1980 Epimetheus 151 57 5.60e17 Walker 1980 Janus 151 89 2.01e18 Dollfus 1966 Mimas 186 196 3.80e19 Herschel 1789 Enceladus 238 260 8.40e19 Herschel 1789 Tethys 295 530 7.55e20 Cassini 1684 Telesto 295 15 ? Reitsema 1980 Calypso 295 13 ? Pascu 1980 Dione 377 560 1.05e21 Cassini 1684 Helene 377 16 ? Laques 1980 Rhea 527 765 2.49e21 Cassini 1672 Titan 1222 2575 1.35e23 Huygens 1655 Hyperion 1481 143 1.77e19 Bond 1848 Iapetus 3561 730 1.88e21 Cassini 1671 Phoebe 12952 110 4.00e18 Pickering 1898

SATURN’S MOONS• MAJOR MOONS (53 + 9):

Pan 1990; Atlas 1980; Prometheus 1980; Pandora 1980; Epimetheus 1980; Janus 1966; Mimas 1789; Enceladus 1789; Tethys 1684; Telesto 1980; Calypso 1980; Dione 1684; Helene 1980; Rhea 1672; Titan 1655; Hyperion 1848; Iapetus 1671; Phoebe 1898

• RINGS: A-Ring, B, C, D, E, F, G.

URANUS• 300 times bigger than the Earth• 84 Earth years to orbit the sun• Strange thing: Orbits the sun on its side• Has rings

NEPTUNE

• 300 times larger than the Earth• Two moons

• Jupiter, Saturn, Uranus, Neptune are called

OUTER PLANETS and GAS GIANTS

• Dwarf planet in Kueper Zone• Rock and ice• Charon is Pluto’s moon• Charon is the COLDEST place on the

entire solar system

ASTEROID BELT• Between the INNER PLANETS and theOUTER PLANETS is the Asteroid Belt• Full of asteroids that orbit the SUN

• ASTEROIDS are made of chunks of rock and some ice and orbit the sun

GALAXIES• Galaxies are identified based on their shape• Clusters of billions of stars with different shapes: spiral,

elliptical, irregular• Galaxies are composed of stars, star clusters, nebulas,

and planetary systems• Classified by shape and by rate of star formation• Spiral galaxies have a bulge at the center and spiral arms.

The Milky Way• Our galaxy is a spiral shape

and is called the Milky Way • Consists of about 200 billion

stars• The sun is located about 2/3 of

the way between the center of the galaxy and the galaxy’s edge

ELLIPTICAL GALAXIES• Elliptical Galaxies are round or oval (cosmic

snowballs) • They have stopped making new stars more

than 10 billion years ago. • They are the largest galaxies in the universe• Contain up to 5 trillion stars • They form by the merging of smaller galaxies

IRREGULAR GALAXIES• Irregular galaxies are galaxies that have

no definite shape• Smallest ones have only about 10 million stars• Form new stars slowly• Some form when galaxies • collide• The Milky Way is consuming a pair of

nearby irregular galaxies

CONTENTS OF GALAXIES

• Galaxies contain stars, planetary systems, gas clouds and star clusters

• Gas Clouds are called nebulas and they are large clouds of gas and dust where stars are born

• Some nebulas glow, other types absorb light and hide stars, and others reflect starlight

STAR CLUSTERS• A globular cluster is a highly

concentrated group of stars that looks like a ball

• May have up to 1 million stars• Open clusters are groups of 100 to

1,000 stars that are close together relative to other stars

QUASARS• Quasars are among the most distant objects in the universe• Star like sources of energy that are located in the centers of

galaxies• They generate energy at a high rate and are among the

most powerful energy sources in the universe• May be caused by massive black holes in the cores of

galaxies• The quasar known as PKS 0637-752 radiates with the power

of 10 trillion suns

ORIGIN OF GALAXIES• Scientists investigate the early

universe by observing objects that are extremely far away in space

• Because light takes time to travel through space, looking through a telescope is like looking back in time

• Looking at distant galaxies reveals what early galaxies looked like

FORMATION OF THE UNIVERSEThe Big Bang Theory• Most galaxies are moving away from each other and

the universe is expanding• About 14 billion years ago, all of the contents of the

universe were compressed under tremendous pressure, at high temperature and high density, into an extremely small volume

• The universe was contracting and all matter squeezed together in one small volume

• Then expanded and cooled• Galaxy formation

FORMATION OF THE SOLAR SYSTEM

• The collision of particles formed bodies the size of boulders and asteroids

• As the mass of particles increased, gravity increased

• Matter in the solar nebula was pulled together by gravity into spheres

FORMATION OF THE SOLAR SYSTEM

• The solar nebula collapsed, rotated• Becomes hot and dense in its center• The gas and dust forms a disk• The disk begins to cool enough for dust

particles to form• Particles begin to collide and form

larger particles

GRAVITY AND THE UNIVERSE• Gravitational attraction pulls objects toward

one another• All objects experience gravity• After the big bang, gravitational attraction

caused the matter distributed throughout the universe to form galaxies

• The mutual attraction between galaxies caused galaxies to cluster

• Even though the distances between galaxy clusters are very large, gravity still acts between them

• Because gravity acts over such great distances, gravity controls the size and shape of the universe

HOW OLD IS THE UNIVERSE?• Astronomers can estimate the age of the universe by

studying white dwarfs, the oldest stars in the Milky Way• White dwarfs are the burned-out cores of stars that

started out with masses that were less than 8 times the mass of the sun

• These stars have cores of carbon and oxygen at the end of the red giant phase

• They lose their atmospheres in the planetary nebula stage• The planetary nebula stage is a stage in which the hot

central region of a star drives off the star’s cooler atmosphere over a period of a few thousand years.

HOW OLD IS THE UNIVERSE?

• Once the star’s atmosphere is lost, all that is left is the carbon-oxygen core- a white dwarf-which is tiny, hot, and dense

• The oldest white dwarfs are 12 billion to 13 billion years old

• Because it took about 1 billion years after the big bang for the first white

• dwarfs to form from the first stars, the universe must be approximately 14 billion years old

THE LIFE CYCLE OF STARS• Stars can exist for billions of years• Scientists study stars at different stages to

understand how they develop• Stars are classified by mass, size,brightness, color, temperature, composition, and age• Stars are different as they age• The fast-expanding gas clouds in the picture show a dying star

LIFE CYCLE OF SUNLIKE STARSPROTOSTARS -1st Stage• A star begins its life as a ball of gas and dust• Gravity pulls the gas and dust into a sphere• As the sphere becomes denser it gets hotter and

hotter to 10,000,0000 C in its center• Hydrogen nuclei combine to become helium• This is called nuclear fusion • Causes energy to be released

LIFE CYCLE OF SUNLIKE STARS

MAIN-SEQUENCE STARS • After it is formed, it enters the main

sequence• Second and longest stage of its life

cycle• Energy is generated in the core of the

star as hydrogen atoms fuse into helium atoms.

• Size changes very little

GIANTS AND SUPERGIANTS• When a main-sequence star uses all of

the hydrogen in its core, helium begins to fuse

• The center of the star shrinks• The atmosphere of the star grows

very large and cools• The star may become a red giant or red supergiant ex. Betelgeuse

WHITE DWARFS• In the final stage of its life cycle, a

sunlike star becomes a white dwarf• Small, hot, and dim star that is the

leftover center of a red giant• No longer generates energy by nuclear

fusion• Slowly cools and becomes smaller• A white dwarf can shine for billions of

H-R DIAGRAM The Sun

*Middle age

*5 billion years old

Blue = Hot

Yellow = Medium Red = Cool

THE AGING OF MASSIVE STARS

• Massive stars use their hydrogen much faster than stars like the sun do

• More energy and they are very hot!• Shorter livesSUPERNOVAS• At the end, a massive star may explode

in a large, bright flash called supernova• A supernova is a gigantic explosion in

which a massive star collapses and its outer layers are blasted into space

PULSARS -If a neutron star is spinning, it is called a pulsar

• Pulsars send out beams of radiation that sweep across space like a lighthouse over the ocean• Detected by radio telescopes as pulses

NEUTRON STARS• The center of the supernova (collapsed

star) may contract into a very small but very dense ball of neutrons

• This ball of neutrons is called Neutron Star

• One teaspoon of matter from a neutron star would weigh 100 million metric tons of Earth

• A lot of energy (100,000 suns)

BLACK HOLES • An object so dense and massive that light

cannot escape its gravity• If the center of a collapsed star has a mass

several times the mass of the sun, the star may contract more because of too much gravity

• The force of the contraction crushes the dense center of the star and leaves a black hole

BLACK HOLES

BLACK HOLES• Black holes do not give off light• Locating them is difficult• If a star is nearby, some gas or dust from

the star will spiral into the black hole and give off X rays

• These X rays allow astronomers to detect the presence of black holes

• The sun will never become a Black Hole• Stars with 10 -100 million times the mass

of the sun• Stellar- Mass Black Hole & Supermassive

Black Hole

INTERPLANETARY DISTANCES• Astronomical Unit (AU) is the average distance

between the sun and Earth (150,000,000 km)• Light minute or light hour • 1s = 300,000 km• 1 min = 18,000,000 km (light minute)• 1 AU = 8.3 light minutes• Used to measure distances within the SOLAR

SYSTEMExample: between planets or the sun and a planet• Light Year: used to measure outside the solar

system =9.5 trillion kmExample: between galaxies and stars

Comets

• Small, loosely packed bodies of ice, rock, and cosmic dust

• The core is rock, metals, and water ice• The coma surrounds the nucleus and is

made of gas and dust• Comet tails—sunlight causes the comet’s

ice to change to gas thus forming the tails• One tail is made of ionized gas (no

electrons) and points away from the sun• The other is made of dust and gas

Comets

• Comets are found in the Kuiper belt (flat ring of objects located beyond Neptune’s orbit)

• Oort cloud--spherical cloud of dust and ice that surrounds the solar system far beyond Pluto’s orbit

ASTEROIDS--Asteroid Beltpg502

• Asteroid Belt is made of asteroids between Mars and Jupiter

• Located between the Inner Solar System and the Outer Solar System

• Asteroids are small (1,000 km)rocky and some metal bodies• Revolve around the sun

Meteoroids

• Dust and debris from asteroids and comets within our solar system• When enter Earth’s atmosphere reach speeds of 35,000-250,000 km/h• Friction heats the meteoroids to thousands of degrees Celsius• Glow brightly

Meteors

• The glowing trails that result when meteoroids burn up in Earth’s atmosphere

Meteorites

• Larger bodies that pass through Earth’s atmosphere without burning up and strike Earth

• Three types: Stony, metallic, Stony-iron meteorites

METEOR SHOWERS• Meteors can be seen on almost any night away from lights• When a large number of small • meteoroids enter Earth’s atmosphere

in a short period of time a meteor shower occurs

• Occurs when Earth intersects the orbits of comets that have left behind a trail of dust

METEOR SHOWERS

POINTS TO REMEMBER• The solar system formed as a result of

gravitational attraction in the solar nebula• Gravity and pressure were major factors in the

formation of the solar system• The sun is a star that produces energy by

nuclear fusion• Astronomers use the astronomical unit to

measure distances in the solar system

POINTS TO REMEMBER• The four planets of the inner solar

system are small, dense, and rocky and are close to the sun

• The inner planets, or terrestrial planets, are: Mercury, Venus, Earth, and Mars

• The planets of the outer solar system have deep, massive gas atmospheres

• Jupiter, Saturn, Uranus, and Neptune are the inner planets or the gas giants

• Pluto is made of rock and ice and is a dwarf planet

POINTS TO REMEMBER• Moons are bodies that are smaller

than planets and that orbit planets• Earth’s moon formed when an object

collided with Earth• The moon’s appearance changes as

the moon revolves around earth• Moons of other planets vary greatly

in size and composition

POINTS TO REMEMBER• Comets, asteroids, and

meteoroids are small bodies in our solar system that orbit the sun

• Comets are small bodies of ice and rock that have very elliptical orbits

• Most asteroids are located in a belt between Mars and Jupiter

• Meteoroids are dust and debris from asteroids and comets

ASTRONOMY

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