Astronomy

The Solar System

What you need to know

• How do the heliocentric and geocentric models of the solar system differ?

• Describe what Kepler discovered about the orbits of the planets.

• Identify two factors that keep the planets in their orbits.

Word Attack

• geocentric

• heliocentric

• ellipse

• inertia

• fusion

• photosphere

• chromosphere

• nuclear

Heliocentric v. Geocentric

• Heliocentric Model Earth and the other

planets revolve around the sun

Nicolaus Copernicus early 1500s

• Geocentric Model Earth is at the center

of the revolving planets Ptolemy (TAHL uh mee)

A.D. 140

The Sun

• The Sun’s Interior• extremely high temperature + extremely high

pressure• hydrogen atoms fuse to form helium• nuclear fusion• temperature in the core reaches 15 million degrees

Celsius

Interior of the Sun

The Sun

• The Sun’s Atmosphere• photosphere - inner layer (creates the light)• chromosphere - middle layer (reddish glow)• corona - outer layer (visible during total eclipse)

The Sun’s Atmosphere

The Sun

• Features of the Sun• sunspots - areas of gas that are cooler than the

areas around them; many are as large as Earth or larger

• prominences - reddish loops of gas linking sunspot regions

• solar flares - hydrogen gas explosions• solar wind - increased by solar flares; can cause

magnetic storms in Earth’s upper atmosphere disrupting radio, telephone, and television signals.

The Sun Now

Sunspots

Sun Prominences

Solar Flares

Solar Wind

The Inner Planets

• Mercury

• Venus

• Earth

• Mars

Mercury

• closest to sun

• 450°C during the day

• -170°C at night

Mercury

Astronomy Textbooks

• Open your textbook to page 64

• Find 5 (five) more facts about Mercury

• Write the 5 facts on your note page next to the slides about Mercury

• You have 5 minutes to read and write

Venus

• known as the “evening star” Venus can be seen in the west after sunset and again as the “morning star” just before sunrise

• “day” is longer than “year” - 7.5 Earth months to revolve around the sun; 8 Earth months to rotate on its axis

• Retrograde rotation (rotating East to West, opposite of most planets and moons)

• Atmosphere contains sulfuric acid and carbon dioxide

Venus

Astronomy Textbooks

• Open your textbook to page 65-66

• Find 5 (five) more facts about Venus

• Write the 5 facts on your note page next to the slides about Venus

• You have 5 minutes to read and write

Earth

Astronomy Textbooks

• Open your textbook to pages 62-63

• Find 5 (five) more facts about Earth

• Write the 5 facts on your note page next to the slides about Earth

• You have 5 minutes to read and write

Mars

• the “red planet”

• polar ice cap at north pole contains water

• polar ice cap at south pole is frozen carbon dioxide

Mars

Astronomy Textbooks

• Open your textbook to pages 67-69

• Find 5 (five) more facts about Mars

• Write the 5 facts on your note page next to the slides about Mars

• You have 5 minutes to read and write

end of Part 1

• When your notes are completed, please work on the worksheet “The Inner Planets”.

• Please complete the worksheet during your study time after school if it is not finished when you leave class.

• Thank you for participating in our science lesson today.

• Have a great day! :)

Vocabulary

• terrestrial planet

• retrograde motion

• greenhouse effect

Inner v. Outer Planets

• Inner Planets 4 (four) small rocky surfaces terrestrial planets

• Outer Planets 4 (four) much larger than Earth do NOT have solid

surfaces gas giants

Outer Planets (aka Gas Giants)

• Jupiter

• Saturn

• Uranus

• Neptune

Jupiter

• atmosphere of hydrogen and helium

• “The Great Red Spot” is a storm like a hurricane

• 17 moons

Jupiter

Astronomy Textbook

• Turn to page 72 -73

• Find 3 facts about Jupiter

• Add these facts to your note pages

Saturn

• second largest planet in the solar system

• chunks of ice and rock orbit in rings

• 5 moons

Saturn

Astronomy Textbook

• Turn to page 73 - 74

• Find 3 facts about Saturn

• Add these facts to your note pages

Uranus

• atmosphere contains traces of methane

• Voyager 2 provided the only photographs we have

• 17 moons

Uranus

Uranus with shadow of eclipse

Astronomy Textbook

• Turn to page 75

• Find 3 facts about Uranus

• Add these facts to your note pages

Neptune

• 30 times Earth’s distance from the sun

• 8 moons have been discovered

Neptune

Astronomy Textbook

• Turn to page 76

• Find 3 facts about Neptune

• Add these facts to your note pages

Outer Planets

• are MUCH larger than inner planets

• have a stronger gravitational force than inner planets and keeps gases from escaping their atmospheres

• may have a partly solid core made of rock, ice, frozen carbon dioxide, and other compounds

Ceres, Pluto, & Eris

• Dwarf Planets - Pluto and any other round object that "has not cleared the neighborhood around its orbit, and is not a satellite.”

Identified Dwarf Planets

Ceres

Eris (2003 UB313)

Pluto

Comets

• A comet has a distinct center called a nucleus. Most astronomers think the nucleus is made of frozen water and gases mixed with dust and rocky material.

• Comet nuclei are described as dirty snowballs. • A hazy cloud called a coma surrounds the nucleus. • The coma and the nucleus together form the comet's head.

Comets

• Scientists think that about 100 million comets orbit the Sun.• The name comet comes from the Latin word cometa which means

"long-haired". • The earliest known record of a comet sighting was made by an

astrologer of the Chinese court in 1059 B.C.• Comets are thought to originate from the Kuiper Belt and beyond.

Asteroids

• Most asteroids revolve around the sun between the orbits of Mars and Jupiter in the Asteroid Belt

• The asteroid belt separates the inner planets from the outer planets

Meteors

• Meteors are bits of space debris falling through Earth's atmosphere

Kuiper Belt

• The Kuiper Belt is often called our Solar System's 'final frontier.' This disk-shaped region of icy debris is about 4.5 to 7.5 billion km (2.8 billion to 4.6 billion miles), 30 to 50 Astronomical Units (AU) from our Sun.

• Its existence confirmed only a decade ago, the Kuiper Belt and its collection of icy objects - Kuiper Belt Objects (KBOs) - are an emerging area of research in planetary science.

• No spacecraft has ever traveled to the Kuiper Belt, but NASA's New Horizons mission, planned to arrive at Pluto in 2015, might be able to penetrate farther into the Kuiper Belt to study one of these mysterious objects.

Where’s the Kuiper Belt?

So what holds our Solar System together?

• Gravity the attractive force between two objects its magnitude depends on their masses and

the distance between them (32)

• Inertia the tendency of a moving object to continue in

a straight line or a stationary object to remain in place (53)

Gravity

• The easiest way to think of gravity is that it's the thing that makes you stick to the Earth. It's like a giant hand that reaches up from the ground, grabs your ankle and holds you down. Gravity affects the amount of force that you exert on the ground. It's like you are pushing on the ground!

You and the earth

Now that you know what gravity is, we can tell you what weight and mass are...

• Mass is just the amount of "stuff" you are made of! No matter where you go in the Universe, you are still made of the same amount of stuff, so your mass is always the same. (Unless, of course, you grow. Then your mass increases.)

• The force of gravity that you push on the ground with is called weight. You might weigh 66 pounds on the Earth... But you would weigh 1/6 of this on the moon (only 11 pounds) because the moon's gravity is 1/6 as strong as the Earths.

How much do you weigh on other planets?

• To find out how much you might weigh on other planets, visit www.sciencemonster.com

"The First Law of Motion!"

• If something is moving, it will keep moving until something stops it. If something is not moving, it will just sit there until something comes along to move it.

• Here is the official, scientific way to say it: An object in motion will continue to stay in

motion unless acted upon by an outside force. An object at rest will continue to stay at rest unless acted upon by an outside force.

Here's a good example:

• Picture yourself racing down the sidewalk on your blades. If you pushed off just once and coasted, how long would it take you to stop? Would you stop a lot faster if you were on asphalt instead of smooth cement? You sure would! That's because there's a lot more friction to slow you down on the asphalt.

• Now, what if you were using ice skates on ice? It would be nice and smooth - less friction - and you'd coast a lot longer right?

Well, there's no friction in space...

• If you were coasting out in space, there'd be nothing to stop you and you'd just keep drifting! Unless something like a comet came along and stopped you. Get the idea? That's inertia!

• What if you put a book on a table... It would just sit there unless you moved it. You could pick it up... or push it... or lift one side of the table so it would side off.

That's inertia!

What does this mean for our Solar System?

• Gravity pulls the planets and other objects toward the sun and each other

• Inertia keeps them traveling along their path

So…

• a planet or object in orbit around the sun or another object will continue along that orbit until another object pushes it or pulls it out of orbit

• an object shooting through space will continue until another object stops it

Well, that’s it folks!

• We’ll study the stars and constellations next!

• Here’s a sneak peak --

Bibliography

• courses.nnu.edu/.../images/Interior_of_sun.jpg• personal.tcu.edu• space.newscientist.com• open2.net/.../208587/carbon_hst_venus95.jpg• astrobiology.nasa.gov• astronomy-for-kidsonline.com/.../meteor.jpg• en.wikibooks.org• sohowww.nascom.nasa.gov/• sti.nasa.gov/• spa3.k12.sc.us• somewhereville.com/gnw/tas/pluto.jpg• cnes.fr• sciencemonster.com/gravity_inertia.html• astropix.com/HTML/C_SPRING/BIGDIP.HTM

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• ©2008