Transcript Asteroids Comets and Meteoriods 2015

Remnants of Rock and Ice
• Asteroids
• Meteoroids (meteorites,
meteor)
• Comets
Remnants of the Solar Nebula
•Small bodies remain virtually _________
unchanged
since their formation _________
4.5 billion years ago
•They carry history of the Solar system in
their compositions
___________, ________, and _______.
numbers
Asteroid means ________,
starlike a rocky leftover
Meteoroid – small rocky material in space
_____
in the atmosphere (falling star)
Meteor – ________________
Meteorite – any piece of rock than fell to the
______
ground from the sky
Comet means _____
hair (Greek), an icy leftover
Asteroids (minor planets)
• Most abundant
_______
between the orbits
of Mars and Jupiter
• Largest is ______,
Ceres
800 km diameter
• Most are much
Smaller,
irregular
_______________
Ceres
Asteroid Eros
Asteroids (minor planets)
Evolution of the Belt
Early in the history of the Solar system, the
belt contained enough planetesimals to form
a planet.
Gravitational tugs from _______
Jupiter created the
gaps.
Two stable zones along Jupiter’s orbit host
two families of asteroids (_______).
Trojans
Jupiter’s Trojan Asteroids
Meteorites
rock that fell
Meteorites are pieces of _____
from the sky.
fireballs (sometimes with sound)
Seen as _______
May cause damage, but most fall into
oceans
______
Earth Pelted with Ashes from Nearby Supernova Explosions
Meteorites
Meteor showers – result of the Earth’s
________________________
passing through a comet orbit
Meteors are ___________
single pieces of comet dust
___________
25 million meteoroids enter Earth’s
atmosphere every day
Meteor showers get their names after
______________
constellations from which they
appear to radiate
Meteor
Showers
(These occur when
earth passes through
cloud of debris along a
comet’s orbit.)
Ionized Trail Generation by
Meteor Crossing Eastern US,
1992
The Origin of Meteorites
________
Primitive meteorites may be either rocky or
carbon-rich
___________
Processed meteorites can be removed
from the surface of a planet by an impact.
There are meteorites from Moon and Mars
found on Earth.
shootingstar_. wmv
http://www.youtube.com/watch?v=cajfFtu_
QPA&feature=related
http://www.youtube.com/watch?v=dpmXyJr
s7iU
https://www.youtube.com/watch?feature=
player_embedded&v=OFDrHe7IzA8
November 2nd, 2015
https://www.youtube.com/watch?v=7dCT407AM
NE November 4th, 2015
http://www.msn.com/enus/video/downtime/extremely-closemeteor-strike-caught-on-film/vi-BBpG13b
Feb. 18, 2016
Primitive Meteorites
Processed Meteorites
Giant meteor hits Earth. Why no one saw it.
The largest meteor since the 2013 impact in
Chelyabinsk, Russia, hit Earth on Feb. 6, 2016.
The fireball fell into the ocean off the coast of
Brazil and released energy roughly equivalent to
13,000 tons of TNT. This is significantly less than
the Chelyabinsk impact, with the equivalent of
500,000 tons of TNT, but it was at least 26 times
as powerful as any of the three impacts NASA
reported in February 2015.
rock and
• Chunks of ________
___
ice in highly
eccentric orbits
• Near sun, ice
sublimates to
__________
“tail”
produce _____
• A couple have been
visited by robotic craft
Comets
Comet Structure
Comets are basically _____________
dirty snowballs where
ice mixes with rocky dust.
Their mean size is a __________________.
few kilometers across
The comet body is called _______.
nucleus
coma
Sublimating ices create _____.
A tail pointing _____
away from the Sun appears.
There are two
___ tails: plasma tail and dust tail.
Comets
Comet Orbits
Comets
Comets contain information about the
_____
outer solar system
Most of them visit the inner part only
once, a few are regular guests
One of the most famous comets is _______
Halley’s
_____.
comet It was discovered by Edmund Halley
in 1682. Its orbital period is 76 years. The
last appearance in 1986. (2062)
Halley’s Comet
Comet Hale-Bopp
Comet ShoemakerShoemaker-Levy 9
Comet ISON
Scott Ferguson captured this image of Comet ISON on Oct. 27 while at a friend's private observatory, Northwest Florida Observatory.
• Discovered in September 2012 by
two Russian amateur astronomers
• Thought to be
making its maiden
voyage to the inner
solar system from
the Oort Cloud.
• ISON made its closest approach
to the Sun on Nov. 28, 2013 when
it came within a mere 730,000
miles (1.2 million kilometers) of
the solar surface.
• ISON broke up after passing the
Sun and was relatively
underwhelming.
Comet 67P/
Churyumov-Gerasimenko
• A European
robot probe
Philea,
released from
the Rosetta
spacecraft,
has made the
first, historic
landing on a
comet.
Philae's
landing
site is on
the head
of the
4km-wide
rubberduckshaped
comet
Leg of
Lander
Nucleus
Photo from Philae shows the surface
during the lander's approach
Earth impacts
• Do we ever get hit?
• Yes! The questions are when and
by what?
size
• Classify events by ____
–Small
–Medium
–Large
Impacts
The ______
larger the ________,
impactor the _________
more rare
the impact
In 1908, an unusual explosion occurred in
Siberia
________.
Arizona formed 50,000
Meteor crater in _______
years ago.
A ____________
larger impactor occurred ___
65 million years
ago perhaps caused the _________________.
dinosaur extinction
Earth impacts: small
• Small: _____
less than ___________
50 m across at top of
atmosphere
all the time
– Happening _____________
– Will burn up or break up in the atmosphere
_________
– Most are very tiny (‘pea’ sized)
Shooting stars
– Meteors! (“_____________”,
“Falling stars”)
• Can see 3 - 5 per hour on a typical night
• 25 million every day!
• 100 tons per day
© AP Photo: Yekaterina Pustynnikova,
Chelyabinsk.ru
http://abclocal.go.com/wls/story?id=8997035
•This meteoroid was only 62 feet wide.
•Traveling at 42,000 mph.
• Burst over Chelyabinsk in February with
the force of 40 Hiroshima-type atom bombs.
•It released a shock wave that shattered
thousands of windows and injured more
than 1,600 people.
•Its flash was bright enough to temporarily
blind 70 people and cause dozens of skinpeeling sunburns just after dawn in icy
Russia.
http://www.redorbit.com/news/video/space_2/1112977820/russianmeteorite-fragment-ural-mountains-lakebed-101713/
Earth impacts: medium
• Medium: ________________
50 m – 1 km across at top
of atmosphere
–Only ~ __________________
one every century or
millennium
____________
–Causes “severe local damage”
–Two great examples from ‘recent’
history
Earth impacts: medium
• The Tunguska event - Siberia, Russia
–Happened in 1908
Flattened a forest
–_________
–Knocked people over _______
200 km (140
miles) away
No crater (exploded just above
–__________
ground)
• The impactor?
–A stony meteorite (?) Size: 30 m
The Tunguska event
The Tunguska event
Earth impacts: medium
• The Berringer Crater, in Arizona
–Happened ______________
50,000 years ago
–The crater:
• _____
1,200 m across
200 m deep
• ____
Earth impacts: medium
• The impactor?
–An iron meteorite
100 m across (50 m on impact)
–____________
–Going _______
40,000 mph!
–Explosion = ____________
20 million tons of TNT
• A moderate atomic bomb
• 2 Mt. Saint Helens
The Berringer crater, Arizona
Earth impacts: large
• Large: ___________________
more than 1 km across at
top of atmosphere
One every ________________
–____
few million years
–Severe global effects
–More than __
2 km can cause
mass extinction
–Most recent: 65 million years
ago
Earth impacts: large
• The K/T extinction event
–Some history…
• ‘K/T’ = ‘Cretaceous / Tertiary’
• 60 % of all species on Earth
disappeared, including the
dinosaurs
• One explanation (there are several):
Earth was hit by a large impactor
Earth impacts: large
• The K/T extinction event
–Evidence for an impact:
Iridium found at that
• _______
geologic level
• A crater near the _________,
Yucatan
in Mexico
The K/T
extinction
event
Earth impacts: large
• The K/T extinction event
–The impactor:
Asteroid
• Probably an ________
• Size: ~ ___________
10 km across
• Energy released:
100 million million tons of TNT
–____
–__
5 million atomic bombs
10 million Mt. Saint Helens
–___
How often is there an impacted?
How often do impacts occur?
How To Avoid Impacts?
Bombs - Detonate close - push object away
Lasers - Pulses to decrease mass, slows
Solar collectors -Vaporize to decrease mass
Kinetic kill – Space speed bumps - slows
Dock & push – Space craft pushes object
Solar sails – Use solar wind to push object
Gravity tractor – position craft close
http://astro1.panet.utoledo.edu/~anatoly/astr1010/materials/324,41,Slide 41
http://campus.pari.edu/sara/arecibo/presentations/fields/294,13,Meteor Trail Recorded During Leonid Meteor Shower,
1998
http://departments.weber.edu/physics/schroeder/astro/lectureslides/356,8,Kuiper Belt objects (other stuff near Pluto)
http://www.phys-astro.sonoma.edu/people/faculty/carico/A100/367,2,Earth impacts