Our word meteor comes from the Greek word meteoron which means "a
thing in the sky."
A meteor, sometimes
called a "shooting star," can be the brightest object in the night
sky, yet meteoroids are the smallest bodies in the solar
system that can be observed by eye. Wandering through space,
perhaps as debris left behind by a comet, meteoroids enter the
earth's atmosphere, are heated by friction, and for a few seconds
streak across the sky as a meteor with a glowing trail.
A brilliant meteor,
called a fireball, may weigh many kilograms, but even a
meteor weighing less than a gram can produce a beautiful trail.
Some of these visitors from space are large enough to survive (at
least partially) their trip through the atmosphere and impact the
ground as meteorites.
Fireballs are sometimes followed by trails of light that persist
for up to 30 minutes; some, called bolides, explode with
a loud thunderous sound.
How can a particle
the size of a grain of sand produce such a spectacular sight? The
answer is the speed at which the meteoroid enters the earth's
atmosphere. Many meteoroids travel at 60-70 kilometers per second.
As a comparison, the shuttle moves around the earth at about 8
kilometers per second.
During its trip
through the atmosphere, meteoroids collide with air molecules,
knocking away materials and stripping electrons from the meteor.
When the stripped atoms recapture electrons, light is emitted. The
color of the light depends on the temperature and the material
On almost any night
a few meteors an hour will be seen from any one place. However,
periodically there are meteor showers, with hundreds of
meteors emanating from the same apparent spot in the sky.
These showers typically last from a few hours to several days.
These showers are usually associated with comet paths, and are
caused by debris expelled by the comet.
day as many as 4 billion meteors, most miniscule in size, fall to
earth. Their masses total several tons, seemingly a large amount,
but negligible compared to the earth's total mass of
When a meteorite
actually hits, the impact can be tremendous. Many meteorites
actually explode on impact or just above the surface leaving
nothing visible but a crater. During impact, debris is
thrown from the crater. This displaced earth is called
the ejecta. It usually contains rocks of different
composition melded together called breccia.
The shape and size
of the crater depends on the size and velocity of impact.
Small diameter meteorites (less than 4 kilometers or 6.4 miles)
usually leave a round bowl crater, while larger meteorites cause
craters with raised centers called the central peak. This peak is
caused by the surface's attempt to rebound from the impact. Huge
impacts can leave multiple rings in the earth's surface in the
same way a rock creates ripples in a pond.
Source: National Resources Canada
The Meteor Crater in the state of Arizona was the first crater to
be identified as an impact crater. Between 20,000 to 50,000 years
ago, a small asteroid about 80 feet in diameter impacted the Earth
and formed the crater.The crater is the best preserved crater on
Earth and measures 1.2 km in diameter.
In 1908 a 200-foot-wide comet fragment slammed into the atmosphere
and exploded over the Tunguska region in Siberia, Russia, with
nearly 1,000 times the energy of the atomic bomb dropped on
Major Meteor Showers (2012)
Comet of Origin: 2003 EH1
Radiant: constellation Bootes
Active: Dec. 28, 2011-Jan. 12, 2012
Peak Activity: Jan. 4, 2012
Peak Activity Meteor Count: 120 meteors per hour
Meteor Velocity: 25.5 miles (41 kilometers) per second
Notes: A waxing gibbous moon will set at about 3 a.m. local time, allowing
for several dark-sky hours of observing before dawn. This shower has a
very sharp peak, usually only lasting a few hours, and is often obscured
by winter weather. The alternate name for the Quadrantids is the Bootids.
Constellation Quadrant Murales is now defunct, and the meteors appear to
radiate from the modern constellation Bootes.
Comet of Origin: C/1861 G1 Thatcher
Radiant: constellation Lyra
Active: April 16-25, 2012
Peak Activity: April 21-22, 2012
Peak Activity Meteor Count: 10-20 meteors per hour
Meteor Velocity: 30 miles (49 kilometers) per second
Notes: A new moon on April 21 guarantees a dark sky in the late night and
early morning hours, making this year ideal for observing from 10 p.m. to
dawn. Lyrid meteors often produce luminous dust trains observable for
Comet of Origin: 1P Halley
Radiant: constellation Aquarius
Active: April 19-May 28, 2012
Peak Activity: May 5-6, 2012
Peak Activity Meteor Count: 10 meteors per hour
Meteor Velocity: 44 miles (66 kilometers) per second
Note: While the shower peaks an hour or two before dawn, the year's
closest and largest full moon will be out all night, resulting in a
moonlit sky that will wash out all but the brightest meteors. Meteor
watchers in the Southern Hemisphere stand the best chance of seeing any
Comet of Origin: unknown, 96P Machholz suspected
Radiant: constellation Aquarius
Active: July 12-Aug. 23, 2012
Peak Activity: July 28-29, 2012
Peak Activity Meteor Count: Approximately 20 meteors per hour
Meteor Velocity: 25 miles (41 kilometers) per second
Notes: It's not a good year for the Delta Aquarids -- light from the
August full moon make them nearly impossible to see.
Comet of Origin: 109P/Swift-Tuttle
Radiant: constellation Perseus
Active: July 17-Aug. 24, 2012
Peak Activity: Aug. 12, 2012
Peak Activity Meteor Count: Approximately 100 meteors per hour
Meteor Velocity: 37 miles (59 kilometers) per second
Notes: Moonlight won't be as big a problem as last year, as its waning
crescent won't rise until after midnight, and the shower peaks from about
10-11 p.m. local on the night of Aug. 12.
Comet of Origin: 1P/Halley
Radiant: Just to the north of constellation Orion's bright star Betelgeuse
Active: Oct. 2-Nov. 7, 2012
Peak Activity: Oct. 21, 2012
Peak Activity Meteor Count: Approximately 25 meteors per hour
Meteor Velocity: 41 miles (66 kilometers) per second
Note: With the second-fastest entry velocity of the annual meteor showers,
meteors from the Orionids produce yellow and green colors and have been
known to produce an odd fireball from time to time.
Comet of Origin: 55P/Tempel-Tuttle
Radiant: constellation Leo
Active: Nov. 6-30, 2012
Peak Activity: Night of Nov. 17, 2012
Peak Activity Meteor Count: Approximately 15 per hour
Meteor Velocity: 44 miles (71 kilometers) per second
Note: The Leonids have not only produced some of the best meteor showers
in history, but they have sometimes achieved the status of meteor storm.
During a Leonid meteor storm, many thousands of meteors per hour can shoot
across the sky. Scientists believe these storms recur in cycles of about
33 years, though the reason is unknown. The last documented Leonid meteor
storm occurred in 2002.
Comet of Origin: 3200 Phaethon
Radiant: constellation Gemini
Active: Dec. 4-17, 2012
Peak Activity: Dec. 13-14, 2012
Peak Activity Meteor Count: Approximately 120 meteors per hour
Meteor Velocity: 22 miles (35 kilometers) per second
Note: The Geminids are typically one of the best, and most reliable, of
the annual meteor showers. This year's peak falls perfectly with a new
moon, guaranteeing a dark sky for the show in the nights on either side of
the peak date. This shower is considered one of the best opportunities for
younger viewers because the show gets going around 9 or 10 p.m.
Credit: NASA, International Meteor Organization
Data compiled from The
British Antarctic Study, NASA, Environment Canada, UNEP, EPA and
other sources as stated and credited Researched by Charles
Welch-Updated daily This Website is a project of the The Ozooe Hole