the solar system and the universe · · 2011-09-20• 71% of earth is covered by water. ... •...

TEACHER INFORMATION SHEETS

THE SOLAR SYSTEM

AND THE UNIVERSE

© Armagh Planetarium 2007

MERCURY

Composition: Gigantic iron core (70% of interior); perhaps partially molten Thin silicate mantle (25%) Thin crust perhaps <100km (60miles) thick

Mass (Earth =1): 0.055

Temp (min / max): Min -170°C (-280°F) Max 430°C (800°F)

Distance from Sun: 0.39 AU

Mean Distance to Earth: 0.61 AU

Length of Day: 59 days (just under 2 months)

Length of Year: 88 days

Surface Gravity (Earth=1): 0.38

Diameter: 4,879km (3,032 miles)

Volume (Earth=1): 0.056

No. of moons: None

Current Missions: Mercury Messenger Orbiter (2004)

Special Features: • Closest planet to Sun.• Highly cratered in appearance, similar to Earth’s moon. • Slightly larger than the Moon (diameter X 1.4)• Highly elliptical orbit and slow rotation = extreme temp variation.• Hot enough to melt lead/cold enough to freeze person.


Composition: Gigantic iron core (70% of interior); perhaps partially molten Thin silicate mantle (25%) Thin crust perhaps <100km (60miles) thick

VENUS


Temp (min / max): 464°C (867°F); little variation


Mean Distance to Earth: 0.28 AU (closest planet to Earth)

Length of Day: 243 days



Diameter: 12,104 km (7,521 miles)


No. of moons: None

Current Missions: Venus Express Orbiter (2005)

Composition: Large nickel-iron (solid) core (50% of interior)Thick silicate mantleThin rocky crust perhaps 50km (30 miles) thickDense CO2 atmosphere

Special Features:

• Spins in opposite direction to the other terrestrial planets.• Volcano-covered surface; most craters erased by volcanic activity.• Dense CO2 atmosphere causing greenhouse effect on planet.• Hot enough to melt lead; clouds of sulphuric acid.• Atmospheric Pressure is x 92 that of Earth.• Can be seen from Earth as bright evening/morning ‘star’.


EARTH

Composition: Only planet with 2 part core: Solid inner core at very high temperature; Outer liquid core is half radius of planet. Both iron-nickelThick mantle of solid silicate rockThin outer crust of volcanic rocks

Atmosphere: 78% nitrogen; 21% oxygen; 1% argonWater vapour also present

Mass: 5.974 x 1024 kg

Temp (min / max): Min -88°C (-126°F) Max 58°C (136°F) Distance from Sun: 149.6 million km (92.9 million miles); 1AU

Length of Day: 23.93 hrs

Length of Year: 365.25 days

Surface Gravity: 1(g)

Diameter: 12,756 km (7,926 miles) Volume: 1.08 trillion km³

No. of moons: One

Special Features: • Earth is the only planet we know of that has life. The area in which life occurs is called the biosphere.• 71% of Earth is covered by water.• Earth’scrustissplitinto7largeplateswhich‘float’onthe semi-molten mantle below.• Where these plates meet are tectonic features such as deep sea trenches, oceanic ridges, high mountain ranges and volcanoes.


Composition: Only planet with 2 part core: Solid inner core at very high temperature; Outer liquid core is half radius of planet. Both iron-nickelThick mantle of solid silicate rockThin outer crust of volcanic rocks

Atmosphere: 78% nitrogen; 21% oxygen; 1% argonWater vapour also present

THE MOON

Composition: Small metallic core (<4% total mass) partially molten?Rocky mantleThick rocky crust (thicker than Earth’s as it cooledandsolidifiedmuchfaster)


Temp (min / max): Min -233°C (-387°F) Max 123°C (253°F) Mean Distance to Earth: 384,400 km

Length of Day: 27.32 days



Volume (Earth=1): 0.02 Current Missions: None

Special Features:

• The Moon is thought to have been formed from material ejected from the Earth during an asteroid collision about 4.5 billion years ago.• It is covered in craters caused by heavy meteorite bombardment.• The Moon is moving away from us at around 4cm every year. • The same side of the Moon (the ‘near side’) always faces the Earth. • In1968,Apollo8wasfirstmannedspacecrafttoleaveEarthorbit, carrying 3 men around the Moon.• NeilArmstrongandBuzzAldrinwerethefirstmenonthemoon on July 20 1969, with Michael Collins in the Apollo 11 command module.• Twelve people have walked on the Moon, all American male astronauts.


MARS

Composition:

Iron & iron sulphide (solid) core (30-40% of interior)Mantle of silicate rockCrust thicker than Earth’s; 120km (75 miles) Thin atmosphere (95% CO2)

Mass (Earth =1): 0.11 Temp (min / max): Min -133°C (-207°F) Max 27°C (80°F)


Mean Distance to Earth: 0.52 AU

Length of Day: 24.62 hrs (v. similar to Earth)





No. of moons: 2 (Phobos & Deimos)

Current Missions: Mars Odyssey Orbiter (2001) Mars Express Orbiter (2003) Spirit & Opportunity Rovers (2003) Mars Reconnaissance Orbiter (2005) Phoenix Lander (2007)

Special Features:• Called Red Planet due to ‘rusty’ rocks of iron oxide. • Surface similar to Earth, with mountains, valleys and polar ice caps. • Largest mountain in Solar System - Olympus Mons 27 km (17miles) high.• Largest canyon in Solar System – Valles Marineris 7km (4.5 miles) deep and 3,800 km (2,400 miles) long.• Evidence that Mars once had lakes, seas and oceans in distant past; perhaps water still remains in lowest areas?• Sandstorms can last for months.


JUPITER

Mass (Earth =1): 317.8 Temp: -110°C (-160°F) at cloud tops

Distance from Sun: 5.2 AU Mean Distance to Earth: 4.2 AU

Length of Day: 10 hrs Length of Year: 12 years

Surface Gravity (Earth=1): 2.64 (at cloud tops)


Volume(Earth=1): 1,321 (over1000Earthscouldfitinside) No. of moons: 63 known at present

Current Missions: None

Special Features:

• Largest planet in Solar System.• Rapid rotation causes banding - bright ‘zones’ and darker ‘belts’.• Great Red Spot – giant storm system over 400 years old. CouldfitthreeEarthsinsideit.• Thin, dark ring system, invisible to even powerful telescopes.• Four Galilean Moons: Ganymede (largest moon in Solar System); Callisto (most cratered moon in Solar System); Io (most volcanic moon); Europa (may have ocean beneath its icy surface).

Composition: Possibly has small solid core of ice and rockInner mantle (>66% of interior) ofdense liquid metallic hydrogenOuter mantle of liquid hydrogen and heliumThin atmosphere 90% hydrogen, 10% helium


SATURN

Composition: Small core of rock and iceInner mantle of liquid metallic hydrogenOuter mantle of liquid hydrogen (50% of planet)Thicker atmosphere than Jupiter; 96% hydrogen 4% helium

Mass (Earth =1): 95.2 Temp: -140°C (-220°F) at cloud tops

Distance from Sun: 9.6 AU Mean Distance to Earth: 8.6 AU Length of Day: 11 hrs Length of Year: 29 yrs


Diameter: 120,536 km (74,898 miles) Volume (Earth=1): 763.6 No. of moons: 60 known at present

Current Missions: Cassini Orbiter (1997)

Special Features: • Extensive ring system composed of dirty water ice ranging in size from dust grains to boulders several metres across.• Rapidrotationcausesvisibleflatteningatpolesandbanding similar to Jupiter.• Leastdenseofalltheplanets–itwouldfloatinwater.• Saturn’s moon Titan is the second largest moon in the Solar System, and is also the only known moon to have a substantial atmosphere.


URANUS

Composition: Small core of rock and iceSlushy inner mantle of ice compounds of water, methane and ammonia Outer mantle of liquid hydrogen and other elementsAtmosphere of 83% hydrogen, 15% helium and 2% methane

Discovered by: William Herschel in 1781

Mass (Earth =1): 14.5 Temp: -214°C (353°F) at cloud tops

Distance from Sun: 19.2 AU Mean Distance to Earth: 18.2 AU Length of Day: 17 hrs Length of Year: 84 yrs



CurrentMissions: None(Onlymission-Voyager2flybyin1986)

Special Features:

• Methane in atmosphere absorbs red light giving the planet a blue-green colour.• Uranus orbits on its side, possibly due to a massive collision in the distant past.• It has a ring system of eleven dark rings thought to be ice particles covered in sooty organic compounds.• All moons named after characters by William Shakespeare & Alexander Pope (e.g. Titania, Oberon are from a Midsummer Night’s Dream)


NEPTUNE

Discovered by: Johann Galle in 1846

Mass (Earth =1): 17.1 Temp: -200°C (-320°F)

Distance from Sun: 30 AU Mean Distance to Earth: 29 AU Length of Day: 16 hrs Length of Year: 165 yrs



CurrentMissions: None(Onlymission-Voyager2flybyin1989)

Special Features:

• Dark ring system similar to that of Uranus.• Due to Pluto’s eccentric orbit, Neptune is sometimes the furthest planet from the Sun.• Cloud belts, zones and turbulent storms similar to Jupiter.• Storms have fastest winds in Solar System at 670 m per second.• Great Dark Spot observed by Voyager 2 in 1989, disappeared by 1994.• Triton is Neptune’s only large satellite and is bigger than Pluto. It is the coldest known object in the Solar System at -235°C (-391°F)

Composition: Small core of rock and iceSlushy inner mantle of water, methane and ammonia (similar to Uranus)Outer mantle of hydrogen and other compounds in icy liquid (similar to Uranus)Atmosphere of 79% hydrogen; 18% helium; 3% methane


Composition: Small core of rock and iceSlushy inner mantle of water, methane and ammonia (similar to Uranus)Outer mantle of hydrogen and other compounds in icy liquid (similar to Uranus)Atmosphere of 79% hydrogen; 18% helium; 3% methane

PLUTO

Composition: Giant rocky core makes up most of planetMantle rich in water iceThin icy crustThin atmosphere 98% nitrogen; 2% methane and CO2

Discovered by: Clyde Tombaugh in 1930

Mass (Earth =1): 0.002 Temp: -223°C (369°F)

Distance from Sun: 39.5 AU Mean Distance to Earth: 29.5AU Length of Day: 6.4 days (almost a week) Length of Year: 248 years


Diameter: 2,390 km (1,485 miles) Volume (Earth=1): 0.006 No. of moons: 3 – Charon, Nix and Hydra

Current Missions: New Horizons (2006) due to reach Pluto in 2015

Special Features:• Charon’s mass is 15% of Pluto’s, making it the largest moon in relation to its parent body in Solar System.• Pluto and Charon rotate at same speed, so always keep the same face to each other.• Nix and Hydra are tiny satellites of Pluto discovered in 2005. They are thought to be between 48-165 km wide.• In 2006, the IAU re-classed Pluto as a dwarf planet.


THE SUN

The Sun is 71% hydrogen; 27% helium and 2% other elements like carbon, nitrogen and iron.Core – nuclear reactions (hydrogen nuclei smashing together to form helium) produce heat and light.Radiation zone – energy from core transported outwards.Convection zone – energy carried to surface by convection.Photosphere – visible surface of Sunwhere e.g. sunspots are observed.Chromosphere – irregular lower atmosphere.Corona – outermost layer of atmosphere extending millions of kminto space. Can be seen during a solar eclipse.

Temp: Core: 15,500,000°C (28 million°F) Surface (photosphere): 5,500°C (9,900°F) Mean Distance to Earth: 149.6 million km (92.9 million miles); 1 AU Axial Rotation Period: 25.38 days

Surface Gravity (Earth=1): 28

Diameter: 1,392,000 km (865,000 miles) Volume (Earth=1): 1,304,000

Current Missions: Several missions including: STEREO (2006); Hinode (2006); SOHO (1995)

TheSun’smagneticfieldalsocausessolarflares(hugeeruptions); coronal loops (streamers of gas joining two points on the Sun’s surface); and prominences (huge strands of cool gas).

Sunspots are cooler regions which appear as dark patches in the photosphere and can be 80,500 km (50,000 miles) in diameter. TheyoccurinregionswheretheSun’smagneticfieldisconcentrated,inhibitingenergyflow.


ASTEROIDS

Asteroids range in size in the following approximate amounts: 100 asteroids >200km (125 miles) across 100,000 asteroids >20km (12.5 miles) across 1 billion asteroids >2km (1.25 miles) across

They were originally divided into three different classes, although there are now many more classes and sub-classes

C-type asteroids : carbonaceous; 75% of known asteroids; outer region of belt S-type asteroids : silicaceous (stony); 17% of known asteroids; inner region of belt M-type asteroids : metallic (nickel and iron); 5% of known asteroids; middle of belt

Asteroids are ‘minor planets’, most ( but not all ) of which are located in the Asteroid Belt between the orbits of Mars and Jupiter.

The Asteroid Belt is 2.1 – 3.3 AU from the Sun. There are millions of asteroids here, but their

combined mass is only 1/20th the mass of the Moon.

Ceres was by far the largest asteroid – bigger than Pluto and containing approx 25% of the combined mass of all theotherasteroidsinthebelt.Ithasnowbeenre-classifiedasa ‘dwarf planet’ – the only one in the Asteroid Belt.

Some asteroids have tiny moonse.g. Ida (above) has a moon

called Dactyl. Others comprise two similar-sized

asteroids orbiting a common centre of mass.

These are called double asteroids.

Near Earth Asteroids (NEAs) orbit within 1.3 AU of the Sun and come close to Earth’s orbit. Only a few

thousand have been found, but over 100,000 which are >100m are

estimated to exist. In 2001, the NEAR Shoemaker probe landed on Eros, an NEA. Before landing, the probe

orbited and photographed the asteroid.


KUIPER BELT& OORT CLOUD

• The Kuiper Belt is a region beyond the orbit of Neptune, from 30-55 AU from the Sun, which contains many small icy bodies left over from the formation of the Solar System. There are an estimated 10 million – 1 billion deep-frozen Kuiper Belt Objects (KBOs) of which >1000 are known.

• The belt is named after Gerrard Kuiper, a Dutch American astronomer who had such good eyesight he was able to see stars four times fainter than those visible to normal eyes.

• The dwarf planet Pluto is the largest known object in the Kuiper Belt. Another dwarf planet, Eris, is found beyond the belt. Neptune’s moon Triton is thought to be a captured KBO.

• KBO’saresometimesdisturbedbythegravitationalinfluenceoftheouterplanets. They enter the inner solar system in highly elliptical orbits and become short-period comets (orbit <200yrs) e.g. Halley’s Comet which orbits every 75-76 years.

Long-period comets (orbit >200 yrs) are thought to originate in the Oort Cloud,

named after Dutch astronomer Jan H. Oort. This is a cloud of

trillions of icy fragments orbiting from the edge of the Kuiper Belt

(50 AU) – 50,000 AU. Comet Hale-Bopp, which orbits every

2,320 years is a long-period comet.

A comet is a body of ice, rock and dust (a ‘dirty snowball’). When it enters the inner solar system its nucleus becomes surrounded by a bright cloud of gas called a coma. Large comets also produce a long glowing tail of gas and dust as they

come close to the Sun.


MILKY WAY

In 2004, astronomers in Chile determined that the galaxy was 13.6 billion years old, making it nearly as old as the Universe

itself.

A galaxy is a giant rotating island of stars. The Milky Way Galaxy is a spiral galaxy with a central bar of stars - a ‘barred spiral’ galaxy. It is the second biggest galaxy

in our local group of around 30 galaxies, after the Andromeda galaxy.

The Milky Way contains about 200 billion stars. The stars at the centre of the galaxy are the oldest and coolest stars and appear yellow/orange in colour. The stars in the outer arms of the galaxy are the younger, hotter stars and appear blue/white in colour.

The Milky Way is named after the faint ‘milky’ band of light which can be seen stretching

across a dark sky. Dark rifts on the band appear to contain no stars, but the starlight here is simply blocked out by interstellar

dust.

The galaxy is about 100,000 light years in diameter. Our Solar System is found about 26,000 LY from the centre in the Orion Arm. It takes the Sun 225 million

years to complete one circuit of the galaxy.

The main disk of the galaxy is about 1000 LY thick. The central core of the galaxy contains a bulge of stars around 15,000 LY thick. We think that a supermassive

black hole may lie here.


EXOPLANETS

These ‘micro-eclipses’ will be observed by telescope on the COROT mission, launched in 2006, as it searches for rocky

planets beyond our Solar System.

An extra solar planet or exoplanet is a planet existing outside our Solar System. To date, over

250 exoplanets have been discovered.

In1995,thefirstexoplanetwasdiscoveredorbiting a star called 51 Pegasi. Unexpectedly, the

planet appeared to be a gas giant like Jupiter. Astronomers were amazed to discover the planet

orbiting so closely to its star that one orbit took only four days (Jupiter’s orbit takes twelve years!)

This illustrated that exoplanets are quite different to those in our Solar System, and prompted much more

researchintofindingthesestrangeworlds.

In April 2007, Gliese 581c was reported in the press as being a potential ‘New Earth’. This planet may be located within its host star’s habitable zone, meaning that water could exist in liquid form on the planet. Gliese 581c is thought to be

50% larger than Earth and almost 5 times its mass.

We have no images of exoplanets as they are too distant, but astronomers can detect their presence by various means e.g. the ‘wobbling’ effect the planet has on its parent star; and also by the transit of the exoplanet across the star, causing its light to

dim slightly.

the solar system and the universe · · 2011-09-20• 71% of earth is covered by water. ... •...

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