Transcript 8. Welcome to the Solar System

SNC1D
SOLAR SYSTEM
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
Terrestrial
Neptune
Jovian
The Layout of the Solar System
• Swarms of asteroids and comets populate
the Solar System
A Few Exceptions to the Rules…
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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 System
Mercury:
Venus:
Earth:
Mars:
Jupiter:
Saturn:
Uranus:
Neptune:
Pluto:
no moons
no moons
one moon (Luna)
two minor moons, Phobos and Deimos
Io ,Europa , Ganymede, Calliso
Titan
several minor moons
Triton
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
belt
Apollo
Earth
Jupiter
Mars
Trojan
belt
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?
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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 Belt
Kuiper Belt
Oort cloud
Asteroid Belt
• Discovered in 1801.
• Piazza found Ceres. Olbers found Pallas.
Previously predicted by Franz Xaver
VonZach.
Asteroid Belt
• The region of space between Mars and
Jupiter; about 2.8AU
• Hundreds of thousands of asteroids
known. Probably millions.
Asteroid Belt
• 3 types of asteroid: Carbonaceous, Silicate,
Metallic
• Even the largest object in the belt, Ceres, is
too dim to see without aid
Asteroid Belt
• Remnants of a planet-formation process
that failed
Kuiper Belt
• Discovered in 1992
• Named for Dutch Astronomer Gerard
Kuiper, who had PREDICTED its
existence in 1951.
Kuiper Belt
• Region beyond Neptune; 30 to over
50AU
• At least 70 000 small, icy, slow-moving,
objects
Kuiper 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 Belt
• History of solar system
Oort Cloud
• Hypothetical spherical cloud. No direct
observations.
• Proposed by Ernst Opik (1932), Jan
Henrik Oort (1950)
Oort Cloud
• 50 000AU; defines gravitational
boundary of solar system
• Source of long-period Comets
Oort Cloud
• Objects composed of ices (water,
methane, and ammonia)
• 2 regions: outer sphere, inner disc
Oort 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/Kui
perBelt.jpg
• http://www.cnes.fr/automne_modules_files/standard/public/p1135_ed7
7069b38b89947b9f6e5678e9af2adkuiper_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/ku
iper.shtml
• Universe: The Definitive Visual Guide