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When Opportunity Knocks
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The Perseid Meteor Shower is going on
NOW
Perseid meteor from the ISS (2011)
A few topics to cover first
• Comets
Comet Swift Tuttle
• Meteoroids
• Meteors
• Meteor Showers
Dec 15, 1992
http://cometography.com/pcomets/109p.html
• Meteorites
Comets
• A small icy Solar System
body
• When close enough to
the Sun will display a
visible coma (a thin, fuzzy,
temporary atmosphere)
and sometimes also a tail.
• These phenomena are
both due to the effects of
solar radiation and the
solar wind upon the
nucleus of the comet.
http://64.107.216.64/cyberspace/Explorers/Solar_System/Comets/
Comet Orbits
http://epoxi.umd.edu/3gallery/comet_orbits.shtml
• Bound: Ellipse shape
(ellipse with e = 0 is a circle)
– stays in the solar system
until the gravitational pull of
a planet knocks it out (Short
and Long Period comets)
• Unbound: Parabolic shape –
goes around once and
doesn’t return – either
burned up from the sun or
thrown out by a planets
gravitational swing. (Single
apparition comets)
Comets
• http://spaceplace.nasa.gov/tails-of-wonder/#
Comets
• Comet nuclei range from
Comet Temple 1
a few hundred meters to
tens of kilometers across
and are composed of
loose collections of ice,
dust, and small rocky
particles.
• Comets have been
observed since ancient
Visited in 2005 by Deep Impact Space Probe
times and have
traditionally been
considered bad omens.
http://epoxi.umd.edu/3gallery/comet_orbits.shtml
Comet Temple 1
• http://spaceplace.nasa.gov/review/cometnucleus/
Deep Impact
http://spaceplace.nasa.gov/comet-impact/
Meteoroids
• As of 2011 the International Astronomical
Union officially defines a meteoroid as "a solid
object moving in interplanetary space, of a
size considerably smaller than an asteroid and
considerably larger than an atom".
• However, very small meteoroids are called
micrometeoroids.
Meteor – or a falling star (but no star)
• A meteor is the visible
path of a meteoroid
that has entered the
Earth's atmosphere.
• Meteors typically occur
in the mesosphere, and
most range in altitude
from 75 km to 100 km.
• Millions of meteors occur in the Earth's
atmosphere every day.
• Most meteoroids that cause meteors are
about the size of a pebble.
• They become visible between about 40 and 75
miles (65 and 120 kilometers) above the Earth.
• They disintegrate at altitudes of 30 to 60 miles
(50 to 95 kilometers).
Leonid Meteor Shower 2010
Meteor Showers
• A meteor shower is the result of
an interaction between a planet,
such as Earth, and streams of
debris from a comet.
• Meteor showers are known to
occur when the Earth passes
near the orbit of a comet and so
are then associated with that
comet.
• We know that as a comet gets
closer to the Sun, it heats up and
sheds some dust and debris.
• Any of the dust or debris that
enters the Earth's atmosphere,
burns up and we see this as a
meteor.
Meteor Showers
• A meteor shower is a
celestial event in
which a number of
meteors are
observed to radiate
from one point in the
night sky.
2012 Perseids
• The Perseids: is the name of the meteor shower associated
with the comet Swift-Tuttle.
• The Perseids are so-called because the point they appear
to come from, called the radiant, lies in the constellation
Perseus,
• The stream of debris is called the Perseid cloud and
stretches along the orbit of the comet Swift-Tuttle. The
cloud consists of particles ejected by the comet as it travels
on its 130-year orbit.
• Most of the dust in the cloud today is around a thousand
years old. However, there is also a relatively young filament
of dust in the stream that was pulled off the comet in
1862. The rate of meteors originating from this filament is
much higher than for the older part of the stream.
Perseid Meteor Shower
Where to look in the sky
http://shadowandsubstance.com/
• When is the best time to view the Perseids?
• How many shooting stars should I be able to
see?
Lets check the FLUXTIMATOR
http://leonid.arc.nasa.gov/estimator.html
• Be aware: The moon will be
near full. The light from the
moon will make it difficult
for you to see meteors.
• Good news: The full moon
doesn’t rise until midnight –
so you should have a nice
dark sky from 9:00 pm –
12:00 am. You should still
see about 5 meteors per
hour
Find Tips for meteor watching here:
• http://stardate.org/nightsky/meteors
Meteor Counting
We can use our computers to count meteors!
This is a seriously cool set up. Practice it first.
• http://meteor-counting.heroku.com/
NEO’s
Meteorite
• If a meteor doesn’t completely burn up in the
Earth’s atmosphere and lands on the Earth it is
called a meteorite.
• Impact Craters
• Believe it or not…
http://titaniumringco.com/meteorite-inlaytitanium-rings15/?gclid=CLqhsK22xqoCFY125QodWwRoyg
More on Meteor Showers
• http://spaceplace.nasa.gov/meteor-shower/