Upload
robyn-wilcox
View
217
Download
0
Tags:
Embed Size (px)
Citation preview
MondaySeptember 20,
2010(Asteroids, Comets, Dwarf Planets, Video – Journey to
Edge of Universe)
The Launch PadMonday, 9/20/10
Identify
Announcements
We will have a test this
Friday.
Assignment Currently Open Pages Date of Notes
on Website Date Issued Date Due
Current Events in Earth/SpaceJupiter is approaching Earth for the closest encounter between the two
planets in more than a decade.The night of closest approach is Sept. 20-21st. This is also called "the night of
opposition" because Jupiter will be opposite the sun, rising at sunset and soaring overhead at midnight. Among all denizens of the midnight sky, only
the Moon itself will be brighter.Earth-Jupiter encounters happen every 13 months when the Earth laps Jupiter
in their race around the sun. But because Earth and Jupiter do not orbit the sun in perfect circles, they are not always the same distance apart when Earth passes by. On Sept. 20th, Jupiter will be as much as 75 million km closer than
previous encounters and will not be this close again until 2022.
Minor Members of the Solar System
Asteroids• Most asteroids lie between the
orbits of Mars and Jupiter.• They are small bodies – the
largest is Ceres, which is about 620 miles in diameter.
• Some asteroids have very eccentric orbits
• Many of the recent impacts on the Moon and Earth were collisions with asteroids
• They usually have irregular shapes and their origin is uncertain .
• We have landed a spacecraft on the asteroid Eros.
The Eccentric Orbits of Some Asteroids
Figure 22.25
Asteroids
Eros
Courtesy: NASA/JPL-Caltech
Eros
Dr. Frank SummersSpace Telescope Science Institute
March 28, 2008
Asteroid Impact Sites on Earth
Manicouagan, Quebec, Canada - a 200-million-year old eroded
impact structure
This impact crater in Winslow, Arizona, is one of about 200 on Earth. At 50,000 years old, it’s also one of the newest. The crater is 1.1 km
(.7 mi) in diameter and 150 m (495 ft) deep. The meteorite that made it weighed 100,000 tons. Most meteorites that hit the ground are too
small to leave a crater, but anything larger than a house explodes just before or during impact and leaves a crater that is much larger
than itself. Photo © Charles and Josette Lenars/CORBIS
Minor Members of the Solar System
Comets• Comets are often described
as large, dirty snowballs.• Composition of comets
▪ Frozen gases▪ Rocky and metallic
materials• The frozen gases vaporize
when near the Sun ▪ This produces a glowing
head called the coma.▪ Some comets may develop
a tail that points away from Sun due to radiation pressure and the solar wind
Minor Members of the Solar System
Comets
Orientation of a Comet’s Tail
as it Orbits the Sun
Figure 22.27
Minor Members of the Solar System
Comets• The origin of comets
is not well known because they form at great distances from the Sun.
• The most famous short-period comet is Halley’s comet, with a 76-year orbital period and potato-shaped nucleus (16 km by 8 km.)
Halley’s Comet
Minor Members of the Solar System
Meteoroids• Called meteors when
they enter Earth’s atmosphere
• A meteor shower occurs when Earth encounters a swarm of meteoroids associated with a comet’s path
• Meteoroids are referred to as meteorites when they are found on Earth
Minor Members of the Solar System
Meteoroids• Meteoroids are
referred to as meteorites when they are found on Earth ▪ Types of meteorites
classified by their composition • IronsMostly iron5%–20% nickel
•StonySilicate minerals with Inclusions of other minerals
Minor Members of the Solar System
Meteoroids• Meteoroids are referred to as
meteorites when they are found on Earth ▪ Types of meteorites classified by
their composition • Stony - irons – mixtures• Carbonaceous chondrites
Rare Composition – simple
amino acids and other organic material
May give an idea as to the composition of Earth’s core
Give an idea as to the age of the solar system
Dwarf Planets Dwarf planets are a new class of
planet.• They orbit the Sun.• They are not the only objects to occupy
their area of space.• The former planet Pluto is the prototype
of this new category.• Many dwarf planets are located in the
Kuiper belt, a band of icy objects found beyond the orbit of Neptune.
Dwarf Planets Pluto
• Pluto is not visible to the unaided eye.
• Discovered in 1930• Now classified as a
dwarf planet• Pluto’s moon Charon
was discovered in 1978.
• Pluto’s average temperature is -210ºC
Video (Part 2)