The Solar System

The Solar System within the Milky way

Composition of the Solar System

The Solar System is composed by the Sun and the celestial bodies that orbit it in ellipses:

• Planets• Satellites• Comets• Asteroids• Meteors

Celestial bodies’ movementsRotation

Is the spinning of a star (s. l.) on its own rotation axis

RevolutionIs the movement of a star (s. l.)

surrounding a bigger one

Day and night Makes seasons

The eclipticAlso called Ecliptic Plane, it is the imaginary plane where the Earth’s orbit is.

The constellations of the Zodiac lie along the ecliptic.

The Sun

Sun’s identity card

• The closest star to the Earth

• Surface temperature: 6 000 ºC

• Mean distance to Earth: 149 000 km

• Diameter: 1 392 000 km

• Hydrogen (73 %), helium (25 %)

Solar protuberances

• Also called Solar Prominences

• Large, bright tongues extending outward from the Sun’s surface

• Often loop-shaped• Top length = 800 000 km• Maybe caused by

thermonuclear reactionsSize comparison among The Earth,

Jupiter and a Solar Protuberance

The eight PlanetsInner planets

•Mercury•Venus•The Earth•Mars

Also called Rocky Planets, they are closer to the Sun.

Outer planets•Jupiter•Saturn•Uranus•Neptune

The gas giant planets, beyond the Asteroids Belt. Made up of hydrogen, helium and other gases. They have rings and many moons.

The Inner Planets

Mercury• 1 orbit = 88 days• 1 rotation = 59 days

• No moons• Closest to the Sun• Little air• Moon-like surface• Surface temp = -170 ºC

to 430 ºC• Rocky with iron core

Venus• Orbit = 225 days• Rotation = 243 days

• No moons• CO2 and clouds of

H2SO4• No water• Hottest planet• Retrograde (clockwise)

rotation• Rocky with iron core

The Earth• Orbit = 365 days• Rotation = 1 day

• 1 Moon• Atmosphere, hydrosphere

and geosphere• Life!• Rocky with iron core• The blue planet (oceans)

Mars• Orbit = 687 days• Rotation = 25 hours

• Moons: Phobos and Deimos

• Polar icecaps• Valleys and canyons.

Liquid water weather?• Atmosphere = CO2• The red planet (red iron

oxide)

Water on Mars• Mars has got ice caps• The North Pole ice

cap is made up of extremely pure water

• In South Pole ice cap there is a small portion of CO2

• CO2 frost deposits in winter and sublimes in springIce cap on Mars’ North Pole, as

seen from Viking 1 space probe

Mons Olympus

The highest mountain in Solar System is Mons Olympus (25

km high), on Mars

Mars’ surface

Seen from space probe Mars pathfinder

Wings to imagination

Is there a human figure on Mars?

The Outer Planets

Jupiter

• Orbit = 12 years• Rotation = 10 hours

• 16 moons (Callisto, Ganymede, Europa, Amalthea, Io)

• 3 rings• Covered by coloured

bands of thick clouds

The largest storm we can imagine

Jupiter’s Great Red Spot is believed to be

a so great anti-ciclonic (high

pressure) storm, that three Earths would fit within its boundaries. It has been observed by astronomers for the last 400 years.

Saturn

• Orbit = 29.5 years• Rotation = 11 hours

• 30 moons• Thousand of rock and

ice rings• Wind speed = 500

m/s• Yellowish surface

Uranus• Orbit = 84 years• Rotation = 17 hours

• 22 moons• 11 rings• Very tilted rotation

axis• Blue surface• The coldest planet

Neptune

• Orbit = 165 years• Rotation = 16 hours

• 8 moons• 4 rings• Great Dark Spot

storm area

Pluto, the no-more planetDiscovered in 1930 by Clyde Tombaugh, it was considered a planet until 2006. Now, it has been demoted to a planetoid, despite to have its own satellite, Charon.

• Its ecliptic is 17 º tilted away from the other eight planets’

• It hasn’t swept its orbit out, since it passes through Kuiper Belt

Pluto’s ecliptic is deviated 17 º from the average Solar System’s

The Moon

Moon’s identity card

• The Earth’s only natural satellite

• Mean distance to Earth: 384 400 km

• Diameter = 3 476 km

• Tempeature: -180 ºC to +110 ºC

• Non self-luminous

The Moon phases

• The Moon’s shape appear to change because of its revolution around the Earth

• The Moon phases are produced by the alignment of the Moon and the Sun in the sky

• The lit side of the Moon always points to the Sun

The Spanish Moon is a liar: when in waxing crescent (creciente) it seems a letter D. When in waning crescent (menguante or decreciente), it seems a C.

Why do we always see the same face of the Moon?

Because the Moon rotates on its axis (red arrows) every 28 days and completes an orbit around the Earth in the same time.

Explanation for children (and not so children)

• Three students needed (two actors and one audience)

• One actor stars the Earth; the other one, the Moon

• The Earth starring will stand, no walking, rotating on himself, slow for not feeling sick.

• The Moon starring will walk sideways around the Earth actor, always looking at him, preventing he to see her back, her dark side

• The Moon starring doesn’t think she has rotated on her axis, since everything she has done is walk facing the Earth

• But the audience, out of the performance, realizes that the Moon has really rotated an entire turn on herself at the same time she has orbited the Earth, because he has seen her face and her back

But there is a real dark side of the Moon…

…that was photographed for the first time on October 7th, 1 959, from the Soviet space probe Luna-3.

The Moon hasn’t got an atmosphere

• The Moon’s so little weight makes it does not have gravity enough to retain gases and form an atmosphere

• Craters caused by meteors collisions will stay unchange for ever since there is no wind or rain to weather them

Man on the MoonOn July 20, 1 969, at 20:18 UTC,

in the frame of Apollo 11 mission, the Eagle lunar

module landed on the Moon. Six hours later, the mission

commander, Neil A. Armstrong, and the pilot Edwin Buzz Aldrin, Jr. stepped for the first time our satellite’s surface.

Michael Collins, meanwhile, orbited the Moon with the spacecraft, waiting for his

companions to come back on board and take them all back

home, to Earth.

That’s one small step for man, one

giant leap for mankind

Moon’s landing conspiracy theories

• There’s no air on the Moon. Why is the flag flapping?

• Astronaut and spaceship shadows’ don’t match

• There are no stars on the background

Not only planetsAsteroids

Comets

Meteors

Asteroids

Rocky celestial bodies that orbit the Sun. Its size can vary from little stones to dwarf planets.Asteroids are distributed in three areas within Solar System:• Asteroids Belt• Kuiper Belt• Oort Cloud

The Asteroids Belt

• Situated between Mars and Jupiter

• Houses 90 % of Solar System’s asteroids

• Thought to be a planet destroyed because of a collision

The Kuiper Belt

• Situated beyond Neptune

• Responsible for Pluto’s demotion to planetoid

The Oort Cloud

Comets

• Celestial bodies made up of ice, dust and gases

• Mostly coming from Oort Cloud• Elliptical orbits around the Sun• Non self-luminous, but reflect the Sun light

Structure of a cometNucleus

Frozen water and gases. When melting, it forms coma and tail

Coma

Giant cloud of dust and gases, surrounding the nucleus

Tail

Electrically charged gases and dust. Always pointing away from the Sun

Some historical comets

• Great Comet of 1882. The brightest comet in modern History. Waiting again for him in 2642

• Great Comet of 1843. The longest tail: 300 million kilometres. Period = 737 years

• Halley. Registered since 240 BC. In 1910, the Earth passed throuhg its tail

• Hale-Bopp. In 1995, its two tails were visible with a naked eye

• Hyakutake. 1996

Two-tailed Hale-Bopp

Three-tailed Donati (1858)

Anti-tailed Arend-Roland (1956)

Was the Star of Bethlehem a comet?

The Florentine painter Giotto di Bondone, who was a witness of Halley Comet in 1301, painted The adoration of the Magi, where the Christmas Star is shown as a comet.

Several efforts have been made in order to link the Star with inusual astronomical events, such as comets, supernovae or an extraordinary conjunction of Jupiter and Saturn.

Tom Sawyer and Huckleberry Finn were born and gone with a comet

Mark Twain wrote in his autobiography: I came in with Halley's Comet in 1835. It is coming again next year, and I expect to go out with it (…) Both went out together in 1910.

Meteors

• Meteoroids are formed from asteroids collision or breaking up

• Meteors and meteoroids that get into Earth’s atmosphere are burnt because of friction against air

• Streak of light left behind them• Shooting stars

Meteor showers

When the Earth passes through a debris

cloud left by a comet.

Do you know any meteor shower? Every August, the Perseids or Tears

of St. Lawrence, shine on the sky. Although they seem to come from Perseus constellation, really are linked to comet Swift-Tuttle.

Some meteor craters on the Earth Surface

Meteor Crater. Winslow, Arizona Chicxulub, Mexico

Tunguska, Siberia

Bosumtwi, Ghana

Did the dinosaurs become extinct because of a meteor collision?

Some scientists hold that dinosaurs became extinct 65 Million Years ago because

a 10 km-diameter meteor collided with the Earth, causing a 90 meters high waves tsunami and throwing to the atmosphere such an amount of dust and glowing stones that the cloud darked sunlight for months. Plants and

animals would die, only surviving the smallest ones.

They claim the exact impact place to be Yucatán peninsula, in Mexico. There should be a crater, 80 km-diameter and 600 meters deep under the ocean. It is also claimed an unusual amount of iridium to be found between geological Cretaceous and Cenozoic Era layers all over the World.

Could a celestial body hit the Earth?

• It is possible,but the huge Jupiter gravity force should attract them towards it

• International space research agencies have developed several programs for monitoring asteroids and meteor tracks

http://neo.jpl.nasa.gov/ Near Earth Objects Program

References• http://csep10.phys.utk.edu/astr161/lect/jupiter/redspot.html • http://www.astrored.net/nueveplanetas/home/overview.html • http://www.tayabeixo.org/sist_solar/cometas/grandes_cometas.htm• http://www.woodlands-junior.kent.sch.uk/time/moon/phases.html • Cross, F. L., ed. Star of Bethlehem.. The Oxford dictionary of the

Christian church. New York: Oxford University Press. 2005• Grima, C., W. Kofman, J. Mouginot, R. J. Phillips, A. Hérique, D.

Biccari, R. Seu, and M. Cutigni (2009), North polar deposits of Mars: Extreme purity of the water ice, Geophys. Res. Lett., 36, L03203, doi:10.1029/2008GL036326.

• "Jesus was born in June", The Daily Telegraph(London), 2008-12-09, retrieved 2011-12-14

• Meléndez Hevia, I. et al. Ciencias de la naturaleza. 1 ESO. Santillana, Madrid. 2.010

• Riach, M. and Shaw, D. Natural and Social Science. Primary 6. Macmillan, Oxford. 2.1012