Our Solar System

Brief History

The Earth is the center of the universe and the sun and moon moved in perfect circles around the earth

Ptolemy

An astronomer living in Egypt who supported Aristotle’s Theory

Nicolaus Copernicus

A Polish astronomer, proposed that the sun was the center of the universe and that all other objects revolved around the sun

Johannes Kepler

Discovered that the planets move in ellipses around the sun. His discoveries supported the ideas of Copernicus

Galileo Galilei

With the aid of a telescope to back up the beliefs of these scientists, Galileo supported Copernicus claims.

Isaac Newton

Formulated the first basic theories of gravitation and all objects in the universe attracted each other.

SUN

The Sun

It is the star at the center of the Solar System.About three quarters of its mass consists of hydrogen, while the rest is mostly helium. The energy of this sunlight supports almost all life on Earth by photosynthesis, and drives Earth's climate and weather

Parts of the Sun

1. Core – sun’s center2. Photosphere – the first layer of the sun3. Chromosphere – innermost layer of the sun’s

atmosphere4. Corona – extensive outer layer of the sun’s

atmosphere5. Sunspots – dark areas on the surface of the

sun6. Solar flares – flashes of bright light are

visible on earth7. Prominence – a giant column of hot gases

formed in the chromosphere that extends to the corona

Stars

A star is a massive, luminous ball of plasma held together by gravity.

Constellations

collection of stars linked together to represent a person, animal or object.

is an internationally defined area of the celestial sphere.

Zodiacal Family

Aquarius, the water bearer

Aries, the ram Cancer, the crab Capricorn, the goat Gemini, the twins Leo, the lion Libra, the scales Pisces, the fish Sagittarius, the archer Scorpius, the scorpion Taurus, the bull Virgo, the virgin

Supergiants

Have diameters up to 1000 times the diameter of the sun

Examples: Rigel, Betelgeuse, and Antares

Stars

By using a spectroscope, astronomers have found out that stars have similar composition, the most common is hydrogen. He, O, Ne, C are other elements

Stars

Blue stars are the hottest and youngest stars followed by white, yellow, red-orange, and red as the oldest stars.

Stars

New stars are born from the gases in the nebulae that clump together because of gravity

Life Cycle of a Star

Protostar -

NEBULA

a region or cloud of interstellar dust and gas

Stars are born in nebulae. Huge clouds of dust and gas collapse under gravitational forces, forming protostars. These young stars undergo further collapse, forming main sequence stars. 

Stars expand as they grow old. As the core runs out of hydrogen and then helium, the core contracts and the outer layers expand, cool, and become less bright. This is a red giant or a red super giant (depending on the initial mass of the star). It will eventually collapse and explode. Its fate is determined by the original mass of the star; it will become either a black dwarf, neutron star, or black hole. 

Our Solar System

Our solar system is made up of:

Sun Planets Their moons Asteroids Comets

Inner PlanetsThe inner four rocky

planets at the center of the solar system are:

Mercury Venus Earth Mars

What is a planet?

The definition of planet set in 2006 by the International Astronomical Union (IAU) states that in the Solar System a planet is a celestial body that:

is in orbit around the Sun, has sufficient mass to assume 

hydrostatic equilibrium (a nearly round shape), and

has "cleared the neighbourhood" around its orbit.

The Planets

Mercury is the planet that is closest to our Sun. Neptune is the farthest. Remember the order of the planets like this:

My Very Educated Mother Just Showed Us Nothing

which meansMercury Venus Earth Mars Jupiter

Saturn Uranus Neptune

MercuryWhat are Mercury‘s features?

smallest planet nearest to the sun one Mercury-year is a quarter Earth-year Mercury is very difficult to be spotted with

the naked eye Mercury has no moons

VenusWhat are Venus‘ features?

it is a medium sized planet, 2.5 times as large as Mercury

second nearest to the sun Venus is very well visible to the naked eye,

always close to the sun before sunrise or after sunset

Venus has no moons

EarthWhat are Earth‘s features?

it is a medium sized planet, a bit larger than Venus

(probably) the only planet with liquid water in our Solar System

the Earth has one moon (probably) the only planet with intelligent

life in our Solar System

MarsWhat are Mars‘ features?

it is a small sized planet, half as large as Earth

Mars is well visible to the naked eye Mars has two moons: Phobos and Deimos Mars has been visited by robotic vehicles:

Pathfinder, Spirit and Opportunity the question for (former) life on Mars is still

unsolved

JupiterWhat are Jupiter‘s features?

it is the largest planet of the Solar System,more than 1.300 Earths could fit inside

Jupiter is well visible to the naked eye The Great Red Spot on its surface is a giant

storm as wide as three Earths Jupiter has 63 moons! (the largest are Io,

Callisto, Ganymede and Europa)

SaturnWhat are Saturn‘s features?

it is the second-largest planet of the Solar System, only a bit smaller than Jupiter

Saturn is well visible to the naked eye the famous rings can be seen with small

telescopes Saturn has at least 34 moons! (recently a

probe landed on Jupiter‘s moon Titan)

UranusWhat are Uranus‘ features?

it is medium sized planet of the Solar System

it is quite far away but still can be spotted with small telescopes

like Saturn, Uranus has a system of rings

NeptuneWhat are Neptune‘s features?

it is medium sized planet of the Solar System, only a little bit smaller than Uranus

it is quite far away but still can be spotted with small telescopes

Neptune has four rings and at least 13 moons

PlutoWhat are Pluto‘s features?

it is already a dwarf planet Since Pluto is far away and so small, you

need a medium-sized professional telescope or a good amateur telescope to spot it.

No one knows what Pluto looks like – it‘s too far away and too small. The picture in the background is an artist‘s rendition.

PlutoPluto is now classified as a

dwarf planet. It is unusual because it is not a gas giant and it does not seem to be terrestrial.

The motion of Pluto’s orbit suggests that Pluto may have been one of Neptune’s moons at one time.

Pluto also has a moon called Charon which is about the same size as Pluto.

Planetary SummaryClosest to the Sun 0.386 0 Brown crater

Chunks of rock none 59 days To orbit Sun

2nd from the Sun

3rd from the Sun

4th from the Sun5th from the Sun

6th from the Sun

7th from the Sun

8th from the Sun

9th from the Sun

0.72

0.5326

10

11

1

0.186

3.8

4

0

1

2

63

33

29

3

13

Hot enough to melt lead

Soil and Water

Reddish coloured soil

Coloured Bands,Great Red SpotSurface temp. isAbout -180oPolar hood overSouth poleIt’s blue.

Cold and rocky

CO2, N2

CO2, N2

N2, O2

H2, He, CH4

H2, He, CH4

H2, He, CH4

H2, He, CH4

none

A 1.7 KM highVolcanoVolcanoes, hurricanes

Volcanoes, glaciersWinds, hurricanes

Windy, cloudy500 km/hwinds

Dark spotRotates on side

Earth’s Moon

Dry, airless, and barren world with extreme temperature

The moon is actually moving away from earth at a rate of 1.5 inches per year. 

The moon is not round, but egg shaped with the large end pointed towards earth. 

The earth rotates about 1000 mph. By comparison, the moon rotates about 10 mph

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

Small pieces of matter (some as grains of sand) that also orbit the sun

When a meteoroid enters the earth’s atmosphere, friction causes it to heat up and glow (meteors)

Some meteors that enter the earth’s atmosphere do not burn up and they land on earth (meteorites)

Comets

Small icy bodies Travel past the Sun Give off gas and

dust as they pass by

Halley’s Comet

It passes the Earth every 76 years. Its last pass was in 1986

What is the difference between an asteroid, comet, and meteoroid?

Asteroid:A relatively small, inactive body, composed of rock, carbon or metal, which is orbiting the Sun.

Comet:A relatively small, sometimes active object, which is composed of dirt and ices. Comets are characterised by dust and gas tails when in proximity to the Sun. Far from the Sun it is difficult to distinguish an asteroid from a comet.

Meteoroid:A small particle from an asteroid or comet orbiting the Sun. 

Movements of the Earth

Rotation – earth rotates on its axis which is tilted at an angle of 23.5O

earth rotates towards the East Revolution – the entire trip around

the sun; 365 days, 5 hours, 48 minutes, and 46 seconds

Terms to be remembered:

Eclipse - an astronomical event that occurs when an object is temporarily obscured, either by passing into the shadow of another body or by having another body pass between it and the viewer.

Terms to be remembered:

Perigee – moon’s orbit is closest to Earth

Apogee – moon’s orbit is farthest to the Earth

Umbra – small inner shadow Penumbra – large outer shadow

Space News

Space exploration is one of the most fascinating features of modern times. Why do you think it is important to explore the space?

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