SOLAR SYSTEMSNC1D

The Layout of the Solar System• Large bodies in the Solar

System have orderly motions– planets orbit

counterclockwise in same plane

– orbits are almost circular

– the Sun and most planets rotate counterclockwise

– most moons orbit counterclockwise

The Layout of the Solar System

• Planets fall into two main categories– Terrestrial (i.e. Earth-like)

– Jovian (i.e. Jupiter-like or gaseous)

Mars NeptuneTerrestrial Jovian

The Layout of the Solar System

• Swarms of asteroids and comets populate the Solar System

A Few Exceptions to the Rules…

• Both Uranus & Pluto are tilted on their sides.

• Venus rotates “backwards” (i.e. clockwise).

• Triton orbits Neptune “backwards.”

• Earth is the only terrestrial planet with a relatively large moon.

The Sun – King of the Solar System

• How does the Sun influence the planets?– Its gravity regulates the orbits of the planets.– Its heat is the primary factor which determines

the temperature of the planets.– It provides practically all of the visible light in

the Solar System.– High-energy particles streaming out from the

Sun influence planetary atmospheres and magnetic fields.

A Brief Tour of the Solar System -- Motions

A Brief Tour of the Solar System – Composition

Major Moons (r > 1,000 km)

in the Solar SystemMercury: no moons

Venus: no moons

Earth: one moon (Luna)

Mars: two minor moons, Phobos and Deimos

Jupiter: Io ,Europa , Ganymede, Calliso

Saturn: Titan Uranus: several minor moons

Neptune: Triton Pluto: one minor moon, Charon

Asteroids and Comets

• Scientists think that the ring of asteroids that lies between Mars and Jupiter was a clump or rocks that just didn’t have enough mass to allow gravity to pull it together into a planet

• There are also comets that orbit our sun.

• Comets are balls of rock and ice that travel in very long stretched out orbits.

Asteroids: basic info• Asteroids are “minor planets” that orbit the sun

(rather than objects that orbit planets as moons). • They are much smaller than the planets, with the

largest being Ceres at about 1,000 km in diameter, (remember that the diameter of the Earth is about 12,800 km) and only another five or so having diameters over 300 km.

• There are roughly 200 or so with diameters over 100 km. There may be on the order of a million with a diameter of kilometer or more.

• The total mass of all the asteroids is probably less than the mass of the smallest planet, Pluto.

Asteroids

Trojan

Trojan

beltbelt

Apollo

Jupiter

Mars

Earth

Comets

Comets are objects composed of dust and ice that come from the far reaches of the solar system on extremely elliptical orbits.

They appear to come from the Kuiper (pronounced Cai-per) Belt (for relatively short period comets) and an area known as the Oort Cloud (for much longer period comets).

Meteors

Meteors are grains of dust and small “rocks” that fall through the atmosphere and glow due to the heat of air resistance as they fall.

Meteorites are the remains that reach the earth’s surface.

Meteroids are the material of meteors in space (before they become meteors). Some of this material comes from dust from comets, some from asteroids.

Why Pluto is not considered a Planet?• It's smaller than any other planet - even smaller than the Earth's moon.

• It's not a gas giant like the Jovian planets -Jupiter, Saturn, Uranus and Neptune and it does not seem rocky like the terrestrial planets -Mercury, Venus, Earth and Mars). However, its nearest neighbours are the gaseous For this reason, many scientists believe that Pluto originated elsewhere in space and got caught in the Sun's gravity. Some astronomers once theorized that Pluto used to be one of Neptune's moons.

• Pluto's orbit is irregular and erratic. The planets in our solar system all orbit the Sun in a relatively flat plane. Pluto, however, orbits the sun at a 17-degree angle to this plane. In addition, its orbit is exceptionally elliptical and crosses Neptune's orbit.

Pluto : The Orbit Problem

Pluto problem : too much company

The remains of the disk which formed the Solar System is still out there beyond Neptune, and Pluto is part of a large crowd of small icy bodies (Kuiper Belt).

Asteroid BeltKuiper BeltOort cloud

Asteroid BeltAsteroid Belt• Discovered in 1801.

• Piazza found Ceres. Olbers found Pallas. Previously predicted by Franz Xaver VonZach.

Asteroid BeltAsteroid Belt• The region of space between Mars and

Jupiter; about 2.8AU

• Hundreds of thousands of asteroids known. Probably millions.

Asteroid BeltAsteroid Belt• 3 types of asteroid: Carbonaceous, Silicate,

Metallic

• Even the largest object in the belt, Ceres, is too dim to see without aid

Asteroid BeltAsteroid Belt

• Remnants of a planet-formation process that failed

Kuiper BeltKuiper Belt• Discovered in 1992

• Named for Dutch Astronomer Gerard Kuiper, who had PREDICTED its existence in 1951.

Kuiper BeltKuiper Belt• Region beyond Neptune; 30 to over

50AU

• At least 70 000 small, icy, slow-moving, objects

Kuiper BeltKuiper Belt• Very faint objects because small, far and

reflect light from Sun

• A million times fainter than faintest we can see with naked-eye

Kuiper BeltKuiper Belt

• History of solar system

Oort CloudOort Cloud

• Hypothetical spherical cloud. No direct observations.

• Proposed by Ernst Opik (1932), Jan Henrik Oort (1950)

Oort CloudOort Cloud

• 50 000AU; defines gravitational boundary of solar system

• Source of long-period Comets

Oort CloudOort Cloud

• Objects composed of ices (water, methane, and ammonia)

• 2 regions: outer sphere, inner disc

Oort CloudOort Cloud

• Comets can not have formed on their current orbit

• Must be held in an outer reservoir

Sources

• http://www.lpl.arizona.edu/faculty/malhotra_preprints/ISP_Nov04/KuiperBelt.jpg

• http://www.cnes.fr/automne_modules_files/standard/public/p1135_ed77069b38b89947b9f6e5678e9af2adkuiper_pluton.jpg

• http://discovermagazine.com/2004/nov/cover/outer-oort.jpg• http://www.myastrologybook.com/OortCloud10q8x7.jpg• http://en.wikipedia.org/wiki/Oort_cloud• http://en.wikipedia.org/wiki/Ceres_(dwarf_planet)• http://www.astro.ubc.ca/~lallen/kbo/general.html• http://www.enchantedlearning.com/subjects/astronomy/solarsystem/

kuiper.shtml• Universe: The Definitive Visual Guide