Our Solar System

Our Solar SystemOur solar system is made

up of: Sun – Star in the center of

a solar system. Nine planets Their moons – a natural

satellite that orbits a primary planet.

Asteroids Comets

Size and Scale of the Universe

• The 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

Image Credit: SOHO/NASA/ESA

Size and Scale of the Universe

• The Sun’s diameter is 109 times greater than that of Earth

• Over 1 million Earths would fit inside the Sun’s volume

• The average distance between the Earth and the Sun is called an Astronomical Unit (AU) - it is about150 million kilometers

• It would take 11,780 Earths lined up side to side to bridge the gap between Earth and Sun (or 107 Suns)

Image Credit: SOHO/NASA/ESA

5

Terrestrial vs. Gaseous Terrestrial vs. Gaseous PlanetsPlanetsTerrestrialTerrestrial

Mercury, Venus, Mercury, Venus, Earth, MarsEarth, Mars

1.1. RockyRocky More denseMore dense

2.2. SmallerSmaller

3.3. More closely spacedMore closely spaced

4.4. Closer to the SunCloser to the Sun

GaseousGaseous

Jupiter, Saturn, Jupiter, Saturn, Uranus, NeptuneUranus, Neptune

1.1. Gaseous, has more Gaseous, has more He and HHe and H Less dense (Saturn Less dense (Saturn

would float)would float)

2.2. LargerLarger

3.3. Spaced farther apartSpaced farther apart

4.4. Farther from the SunFarther from the Sun

Inner PlanetsThe inner four rocky

planets at the center of the solar system are:

Mercury Venus Earth Mars

Mercury

Planet nearest the sun Second smallest planet Covered with craters

As a result of having no atmosphere to protect it from foreign objects hitting its surface.

Has no moons or rings About size of Earth’s moon

Venus Sister planet to Earth – similar in size and

density. Has no moons or rings Hot, thick atmosphere

High composition of CO2 (Greenhouse Effect) Very hot

Brightest object in sky besides sun and moon (looks like bright star)

Covered with craters, volcanoes, and mountains

Earth Third planet from sun Only planet known to have life and liquid

water(big reason for life). Atmosphere composed of composed of

Nitrogen (78%), Oxygen (21%), and other gases (1%).

Due to its position in the solar system relative to the sun and composition of atmosphere it makes it an ideal planet for supporting life.

The Earth: • -is the third planet from the Sun,• -rotates on its imaginary axis counterclockwise every 24 hours or 1 day, -revolves around the sun every 365 days or 1 year.The path that the Earth and all the planetsfollow around the sun is called an orbit.

What keeps planets in orbit? • Due to the downward force of gravity and the

forward force due to the movement of the planets.

• Gravity is the force of attraction between objects that is due to their distance from one another and their masses.

• The closer two objects are together the stronger the force of gravity.

• The more massive two objects are the stronger the force of gravity.

What keeps planets in orbit? • Gravity also helps to explain why the planets

closest to the sun move around the sun at a faster pace than those farther away from the sun.

• This is due to the force of gravity being stronger on the planets closest to the sun than those farther away from the sun.

Mars Fourth planet from sun Appears as bright reddish color in the

night sky Surface features volcanoes and huge

dust storms Has 2 moons Most studied planet other than earth.

This is because its characteristics are closest to being able to support life.

ASTEROID BELT

•Most asteroids can be found in the Asteroid Belt, which is located between Mars and Jupiter. Asteroids are rocky and metallic objects that orbit the Sun, but are too small to be considered planets. They are known as minor planets. Asteroids range in size from Ceres, which has a diameter of about 1000 km, down to the size of pebbles.

Asteroids

Small bodies Believed to be left

over from the beginning of the solar system billions of years ago

100,000 asteroids lie in belt between Mars and Jupiter

Largest asteroids have been given names

Meteoroids and Meteorite

Meteoroids are loose dust particles that come from Comeroid. Most areVery small. When it enters Earth’s atmosphere it forms a bright light, ashooting star. Most meteoroids break up in the Earth’s atmosphere.When they break up it is called a meteorite.

Comets

They are like dirty snowballs

Small icy bodies Travel past the Sun Give off gas and

dust as they pass by

Outer Planets

The outer planets composed of gas are :

Jupiter Saturn Uranus Neptune

Jupiter Largest planet in solar

system Brightest planet in sky 60+ moons Strong magnetic field Giant red spot Has small Rings

Saturn 6th planet from sun Beautiful set of rings 31 moons Largest moon, Titan, Easily visible in the

night sky Voyager explored

Saturn and its rings.

Uranus 7th planet from sun Has a faint ring

system 27 known moons Covered with clouds Uranus sits on its side

with the north and south poles sticking out the sides.

Neptune

8th planet from sun Discovered through

math 7 known moons Triton largest moon Great Dark Spot

thought to be a hole, similar to the hole in the ozone layer on Earth

Outermost Planet

Pluto, the outermost planet, is a small solid icy planet is smaller than the Earth's Moon.

There is much debate to its being considered a planet and today it is considered a dwarf planet.

Explore the Universe and expand your mind

Susan HammondTTlJune 2003

The Size and Distance Scale Of The Solar System

• Our Earth is just one of several Planets that revolve around our Sun, the primary and central object of our Solar System.

• Since the entire Solar System, including our Earth, was created about the same time (about 4.6 billion years ago), our understanding of the origin and properties of the Solar System, the Sun, and its other members are important to our understanding of Earth itself.

• We consider the size of our Earth to be very large, in comparison with most sizes and distances we deal with in our daily lives.

• However, the size of the Earth is very small compared to the size of the Solar System, which consists of the Sun and its family of planets, of which our Earth is only about average in size.

EARTH AND THE SOLAR SYSTEM

The Size and Distance Scale Of The Solar System

• In turn, the size of our Solar System is very large compared to the size of our Earth, or even the largest planet, Jupiter.

• The distance from our Earth to the Moon is about 238,000 miles or 384,000 kilometers (nearly 100 times Earth’s diameter, or about 30 times the distance around the Earth at its equator).

• The distance from our Earth to the Sun is about 93,000,000 miles or 149,600,000 kilometers (more than 390 times the distance to the Moon).

• The most distant major planet from the Sun, Neptune, is 30 times Earth’s distance from the Sun.

• The nearest stars in our Galaxy, the star system of Alpha Centauri, is 9,000 times Neptune’s distance from the Sun!

SIZES AND DISTANCES IN THE SOLAR SYSTEM

SizesDiameters of Solar System Members:

Sun = 1,392,000 kmMercury = 4,878 km

Venus = 12,104 km

Earth = 12,756 km

Mars = 6,794 km

Jupiter = 142,984 km

Saturn = 120,536 km

Uranus = 51,118 km

Neptune = 49,530 km

Pluto = 2,304 km

Mean Distance from Sun

57,900,000 km = 0.387 AU

108,200,000 km = 0.723 AU

149,600,000 km = 1.000 AU

227,900,000 km = 1.524 AU

778,300,000 km = 5.203 AU

1,427,000,000 km = 10.07 AU

2,871,000,000 km = 19.19 AU

4,497,000,000 km = 30.06 AU

5,914,000,000 km = 39.53 AU

Earth’s Moon = 3,476 km Mean Distance from Earth = 384,400 km

Relative Sizes of Planets in Our Solar System

Mercury Venus Earth and Moon Mars

The Planets of Our Solar SystemThe Inner Planets

Sizes to Scale

The Planets of Our Solar System

Jupiter

Saturn

Uranus

NeptunePluto

The Outer Planets

Earth Included for Scale.

The Size and Distance Scale of The Solar System

• The size of our Solar System, if defined by the diameter of Pluto’s orbit, is about 40 times the diameter of Earth’s orbit around the Sun.

• If we consider also the most distant Kuiper Belt objects discovered to date, up to 90 times Earth’s distance from the Sun, the diameter of our solar system would be increased accordingly.

• However, the distance to the nearest star other than our Sun is vastly larger than the size of our Solar System.

• The distances to stars can be estimated by comparing their observed brightnesses with that of our Sun, if they are known to be similar to our Sun in other respects (as determined, for example, by spectroscopic measurements).o The nearest stars to our solar system, the star system Alpha

Centauri, is at a distance about 9000 times Neptune’s distance, or 6800 times Pluto’s maximum distance, from our Sun!

o If our solar system were scaled to the size of a quarter (with Pluto’s orbit about 1 inch in diameter) the Alpha Centauri system would be at a distance of about 285 feet!

Size and Scale of the Universe

RealmActual Size

(diameter in km)

Actual Size(in light-years)

Multiple“X” larger than Earth

Scale Model

Earth 12,700(1.27E+4)

1.4 billionths(1.4E-9)

1 salt grain(0.1 mm)

Sun 1.39 million(1.39E+6)

1.5 ten-millionths(1.5E-7)

109(1.09E+2)

gum ball(1.09 cm)

Solar System 30 billion(3.0E+10)

0.0032(3.2E-3)

2.34 million(2.34E+6)

football stadium

(234 meters)

Solar Neighborhood

378 trillion(3.78E+14)

40(4.0E+1)

30 billion(3.0E+10)

~ size of Moon(3,480 km)

Galaxy 946 quadrillion(9.46E+17)

100,000(1.0E+5)

75 trillion(7.5E+13)

5.4 Suns (7.5 million km)

Local Group(of galaxies)

62 quintillion(6.15E+19)

6.5 million(6.5E+6)

4.8 quadrillion(4.8E+15)

orbit of Mars -diameter

(~3 AU)

Local Supercluster

1.2 sextillion(1.2E+21)

130 million(1.3E+8)

97 quadrillion(9.7E+16)

orbit of Neptune

-diameter

(~60 AU)

Universe 860.9 sextillion(8.6E+23)

91 billion(9.1E+10)

68 quintillion(6.8E+19)

Oort Cloud-radius

(48,000 AU or 0.76 ly)

Size and Scale of the Universe

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

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Remember that the sun is the center of our solar system and the Earth is revolving around

the sun as the year goes by and rotating on its axis.

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But at the same time, the moon is

revolving around the earth and rotating

on its own axis. The relative position of

the moon, Earth, and the sun causes the

phases of the moons.

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The moon revolves around the earth approximately every 28 days. Its rotation is also approximately 28 days. So the same side of the moon is always facing the earth.

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The Moon does not give off its own light but reflects light from the sun. Half of the moon that faces the earth is not always

the half that is being lit by the sun.

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The light from the sun is hitting the side

of the moon facing away from the Earth.

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Approximately one week later,

we see half of the lighted side of

the moon. This is called a first

quarter moon.

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Two weeks after the new moon, a

full moon appears. The entire lighted

side of the moon is facing earth.

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Three weeks after the new moon, a

third quarter moon appears. We can see half of the lighted surface of

the moon from earth.

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Four weeks after the new moon, another new moon appears and the

cycle starts again.

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In between each of the

quarter phases are

other distinct phases.

Waxing means to

grow

Gibbous means to

be humpbacke

d

Waning means to

decrease

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•There are two high tides and two low tides each

day.

• Tides are caused by the pull of both the sun and the moon on the Earth.

•Changes in the positions of the Earth, sun, and

moon affect the height of the tides throughout the

month.

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•Caused when the earth, moon, and sun are in a straight line

•The combination of the gravitational pull of the sun and moon cause the ocean of the Earth to Bulge.

•Spring tides occur during new and full moons.

•Spring tides have the greatest range between high and low tides. Really high, high tides and really low, low tides.

•Named from an Old English term meaning to jump -- NOT FROM THE SEASON

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•When the earth, moon, and sun are at a right angle

•Occur during first and third quarter moons.

•Produce the least range between high and low tide.

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A solar eclipse occurs when the moon gets between Earth and the sun, and the moon casts a shadow over Earth.•A lunar eclipse occurs when the Earth blocks the sunlight from reaching the moon.

Question: Why does the full moon appear to be red during certain times of the year?

Answer: The light from the sun gets bent as it passes through our atmosphere causing it to appear red.

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Occurs when the moon passes between

the Earth and sun, blocking the sunlight from reaching Earth.

Total solar eclipses are visible on Earth for only a few hundred miles wide. A lunar eclipse visible for at

least half the earth.