THE METEORS ASTEROIDS & COMETS
Little chunks of rock and debris in space are called meteoroids. They become meteors — or shooting stars — when they fall through a planet’s atmosphere; leaving a bright trail as they are heated to incandescence by the friction of the atmosphere. Pieces that survive the journey and hit the ground are called meteorites.
- The meteor glimpsed from a satellite
When on Feb 15 2013 With a blinding flash and a booming shock wave, a meteor blazed across the western Siberian sky Friday and exploded with the force of 20 atomic bombs, injuring more than 1,000 people as it blasted out windows and spread panic in a city of 1 million.
“There was panic”.
Some elderly women started crying out that the world was Ending.
“It was quite dark, but it suddenly became as bright as if it was day.
One local said it ‘was like a scene from the Armageddon movie.
Some feared a plane was about to fall out of the sky while others thought the world was ending.
The People had no idea what was happening,”
It was because its been more than 1oo years since the world has witnessed a big meteors impact on the face of the Earth. even though the Earth is constantly bombarded by objects from space but mostly by much smaller rocks. Rocks that are this size (5-15 meters) barely impact the Earth, If ever it happens than; As the Earth is mostly covered by ocean water so the events would not be noticed as often.
So all we know about these is “the Meteor Shower” or “Celestial Fireworks” and of course that its all for fun and for sky watchers. We hardly give any thoughts or interest to have an actual understanding like how dangerous it can be, how to react and respond for our own safety in a situation like, what happened in Russia.
As we know that “about 1,200 people had been injured, at least 200 of them children.. Do you know why most of them got injured ?
Many of them were infact watching the Meteor’s streaking, whizzing, lighting and crashing at that time standing on their balcony and windows, still they really have know idea what can be the aftermath of the crash.
Despite of taking safe positions or moving outdoor Many people infact came further close to their windows in curiosity to watch on the happenings.
That is where they got wronged, the moment the meteor crashed..It caused a devastating sonic boom that ripped through buildings and exploded windows, eventually they got injured by the shattered window panes and their flying glasses.
The immense pressure of the wave also tore the roof off a factory and a couple of apartments. Scientists estimated the meteor unleashed a force 20 times more powerful than the Hiroshima bomb.
The blinding flash and The booming shock wave blew in an estimated 100,000 square meters (more than 1 million square feet) of glass.
And the most important point is that “majority of the people injured, were got injured from shards of glass. Even the official report says “Most of the injuries were caused by flying glass”. According to city officials, who said 3,000 buildings in Chelyabinsk were damaged.Read further down the page about the meteor crash in Russia…
Asteroids, meteors and meteorites
When learning about space it can sometimes be difficult to know the difference between all of the amazing objects out there. The following terms are often confused with each other so let’s answer the question: What are these elements of space Meteors,meteoroid, meteorite, Asteroids and Comets.
- Asteroids are small bodies that orbit the Sun as the Earth does
- Larger asteroids are called planetoids or minor planets, smaller ones often called meteoroids
- Once any of these enters our planet’s atmosphere, it becomes a meteor
- Many meteors break into pieces or burn up entirely as they speed through the atmosphere
- Once meteors or fragments actually hit the earth’s surface, they become meteorites
A meteoroid that burns up as it passes through the Earth’s atmosphere is known as a meteor. If you’ve ever looked up at the sky at night and seen a streak of light or ‘shooting star’ what you are actually seeing is a meteor.
- A meteoroid is a small rock or particle of debris in our solar system. They range in size from dust to around 10 metres in diameter (larger objects are usually referred to as asteroids).
- A meteoroid that burns up as it passes through the Earth’s atmosphere is known as a meteor. If you’ve ever looked up at the sky at night and seen a streak of light or ‘shooting star’ what you are actually seeing is a meteor.
- A meteoroid that survives falling through the Earth’s atmosphere and colliding with the Earth’s surface is known as a meteorite.
- The fastest meteoroids travel through the solar system at a speed of around 42 kilometres per second (26 miles per second).
- The Earth’s atmosphere experiences millions of meteors every day.
- Meteors are easier to see during the lower light conditions of night.
- A small percentage of meteoroids fly on a path that goes into the Earth’s atmosphere and then back out again, they are known as Earth grazing fireballs.
- When many meteors occur in a close time frame in the same part of the sky it is called a meteor shower.
- Around 500 meteorites reach the Earth’s surface every year but of those only around 5 ever make it to scientists for study.
- Meteorites that are observed as they fall through the Earth’s atmosphere and later recovered are called ‘falls’, all others are called ‘finds’. To this date there have been around 1000 collected ‘falls’ and 40000 ‘finds’.
Where do they come from? They probably come from within our own solar system, rather than interstellar space. Their composition provides clues to their origins. They may share a common origin with the asteroids. Some meteoritic material is similar to the Earth and Moon and some is quite different. Some evidence indicates an origin from comets.
Several “shooting stars” or meteors per hour can usually be seen on any given night. Sometimes the number of meteors seen increases dramatically: these are termed “meteor showers”. In fact, some meteor showers occur annually or at rather regular intervals. For example, there are generally more visible “shooting stars” during the autumn and winter of the year. The number always increases after midnight and is usually greatest just before dawn. Perhaps the most famous are the Perseids, which peak around August 12 every year.
Meteor showers are usually named after a star or constellation which is close to the radiant (the position from which the meteors appear to come). Many of the meteor showers are associated with comets. The Leonids are associated with comet Tempel-Tuttle; Aquarids and Orionids with Halley, and the Taurids with Encke.
Meteorites may look very much like Earth rocks, or they may have a burned appearance. They may be dense metallic chunks or more rocky. Some may have depressioned (thumbprint-like), roughened or smooth exteriors. They vary in size from micrometer size grains to large individual boulders. The largest individual meteorite found is the Hoba meteorite in southwest Africa, which has a mass of about 54,000 kg and mostly consists of iron.
Considering the vast infall of meteorites, one cannot help but wonder if anyone has been hurt or killed by meteorites. There are only a few documented cases on record. A shower of stones fell upon Nakhla, near Alexandria, Egypt on 28 June 1911, one of which allegedly killed a dog. On 30 November 1954, Mrs. Hewlett Hodges of Sylacauga, Alabama was severely bruised by an 8 pound stony meteorite that crashed through her roof. This is the first known human injury.
Most meteoritic samples are either iron (actually nickel-iron alloy); stony, which are predominately rocky-silicates; or stony-iron.
While most meteors burn up before reaching the Earth’s surface, many meteoroids break apart in the upper atmosphere, and become “fluffy meteors.” This “fluffy” nature indicates a loose structure or vapor grown crystal aggregates. This gives rise to theories that some meteoroid material was aggregated — that some were subjected to heating-vaporization-condensation. This contrasts with the idea that meteoroids originated from an exploded planet, planetoid or asteroid.
Sixteen meteorites have been found in Antarctica that are believed to have originated on the planet Mars. Gases trapped in these meteorites match the composition of the Martian atmosphere as measured by the Viking spacecraft, which landed on Mars in the mid-1970s. Controversy continues about whether structures found in one of these meteorites, known as ALH 84001, might be fossil bacteria or geologic structures.
Much remains to be learned about meteorites and their origins.
Asteroids are rocky, airless worlds that orbit our sun, but are too small to be called planets. Tens of thousands of these “minor planets” are gathered in the main asteroid belt, a vast doughnut-shaped ring between the orbits of Mars and Jupiter. Asteroids that pass close to Earth are called Near-Earth Objects (NEOs).
Asteroids, sometimes called minor planets, are small, rocky fragments left over from the formation of our solar system about 4.6 billion years ago. Most of this ancient space rubble can be found orbiting the sun between Mars and Jupiter. Asteroids range in size from Ceres, about 952 km (592 miles) in diameter, to bodies that are less than 1 km (0.6 mile) across. The total mass of all the asteroids is less than that of Earth’s Moon. Even with more than one-half million asteroids known (and there are probably many more), they are still much more widely separated than sometimes seen in Hollywood movies: on average, their separation is in excess of 1-3 million km
Early in the history of the solar system, the formation of Jupiter brought an end to the formation of planetary bodies in the gap between Mars and Jupiter and caused the small bodies that occupied this region to collide with one another, fragmenting them into the asteroids we observe today. This region, called the asteroid belt or simply the main belt, may contain millions of asteroids. Because asteroids have remained mostly unchanged for billions of years, studies of them could tell us a great deal about the early solar system.
Nearly all asteroids are irregularly shaped, though a few are nearly spherical, and are often pitted or cratered. As they revolve around the sun in elliptical orbits, the asteroids also rotate, sometimes quite erratically, tumbling as they go. More than 150 asteroids are known to have a small companion moon (some have two moons). There are also binary (double) asteroids, in which two rocky bodies of roughly equal size orbit each other, as well as triple asteroid systems.
The three broad composition classes of asteroids are C-, S- and M-types. The C-type asteroids (carbonaceous) are most common. They probably consist of clay and silicate rocks and are dark in appearance. C-type asteroids are among the most ancient objects in our solar system. The S-types (silicaceous) are made up of silicate (stony) materials and nickel-iron. M-types (metallic) are made up of nickel-iron. The asteroids’ compositional differences are related to how far from the sun they formed. Some experienced high temperatures after they formed and partly melted, with iron sinking to the center and forcing basaltic (volcanic) lava to the surface. One such asteroid, Vesta, survives to this day.
Jupiter’s massive gravity and occasional close encounters with Mars or another object changed the asteroids’ orbits, knocking them out of the main belt and hurling them into space in both directions towards or away from the sun, across the orbits of the planets. Stray asteroids and asteroid fragments have slammed into Earthand the other planets in the past, playing a major role in altering the geological history of the planets and in the evolution of life on Earth.
Scientists monitor asteroids whose paths intersect Earth’s orbit. These are Near Earth Objects (NEOs) that may pose an impact danger. Besides optical observations, radar is a valuable tool in detecting and monitoring potential impact hazards. By bouncing transmitted signals off objects, images and information can be derived from the echoes, such as the asteroid’s orbit, rotation, size, shape, and metal concentration.
Asteroid DA 14
Interestingly We have just witnessed an asteroid named DA 14 passing very close to earth’s gravitational field.
On February 16 2013 the asteroid 2012 DA 14 made the closest recorded pass of an asteroid to the Earth.
A 50-meter asteroid has skimmed past the earth at a distance of 17,000 miles, closer than any other object of its size in history. The 2012 DA 14 rock hurtled past inside the orbit of some satellites on the same day shards of meteorite came to earth in Russia. Nasa scientists said the timing of the two cosmic events was merely coincidental.
NASA space missions have flown by and observed asteroids. The Galileospacecraft flew by asteroids Gaspra in 1991 and Ida in 1993; the NEAR-Shoemakermission studied asteroids Mathilde and Eros; and Deep Space 1and Stardust both had close encounters with asteroids.
In 2005, the Japanese spacecraft Hayabusa landed on the near-Earth asteroid Itokawa in order to collect samples. Hayabusa returned to Earth in June 2010, and the tiny asteroid particles collected in the capsule are currently being examined. Hayabusa was the first spacecraft to successfully land, take off and collect samples from the surface of an asteroid.
Comets are cosmic snowballs of frozen gases, rock and dust roughly the size of a small town. When a comet’s orbit brings it close to the sun, it heats up and spews dust and gases into a giant glowing head larger than most planets. The dust and gases form a tail that stretches away from the sun for millions of kilometers.
In the distant past, people were both awed and alarmed by comets, perceiving them as “long-haired” stars that appeared unpredictably and unannounced in the sky. To some ancient observers, an elongated comet looked like a fiery sword blazing across the night sky. Chinese astronomers kept extensive records for centuries, including illustrations of characteristic types of comet tails. They recorded the times of cometary appearances and disappearances in addition to celestial positions. These historic comet annals have proven to be a valuable resource for later astronomers.
We now know that comets are leftovers from the dawn of the solar system around 4.6 billion years ago, and consist mostly of ice coated with dark organic material. They have been referred to as dirty snowballs. They may yield important clues about the formation of our solar system. Comets may have brought water and organic compounds, the building blocks of life, to the early Earth and other parts of the solar system.
Each comet has a tiny frozen part, called a nucleus, often no bigger than a few kilometers across. The nucleus contains icy chunks and frozen gases with bits of embedded rock and dust. The nucleus may have a small rocky core.
As theorized by astronomer Gerard Kuiper in 1951, a disc-like belt of icy bodies exists just beyond Neptune, where a population of dark comets orbits the sun in the realm of Pluto. These icy objects, occasionally pushed by gravity into orbits bringing them closer to the sun, become the so-called short-period comets. They take less than 200 years to orbit the sun, and in many cases their appearance is predictable because they have passed by before.
A comet warms up as it nears the sun and develops an atmosphere, or coma. The sun’s heat causes ices on the nucleus surface to change to gases so that the coma gets larger. The coma may be hundreds of thousands of kilometers in diameter. The pressure of sunlight and high-speed solar particles (solar wind) blows the coma materials away from the sun, forming a long, and sometimes bright, tail. Comets actually have two tails — a dust tail and a plasma (ionized gas) tail.
Most comets travel a safe distance from the sun — comet Halley comes no closer than 89 million km (55 million miles)
This is the most familiar comet for us as it was seen in larger part of the world and just past near the earth in the year 1986.
1705: Edmond Halley determines that the comets of 1531, 1607 and 1682 are the same comet and predicts its return in 1758. The comet arrives on schedule and is later named Halley’s Comet.
1986: An international fleet of five spacecraft converges on comet Halley as it makes its regular (about every 76 years) pass through the inner solar system.
On Friday morning February 15 2013 a rare event took place, residents of Russia’s Chelyabinsk region were shocked by a giant fireball streaking across the sky. The explosion, caused by a small meteoroid entering the atmosphere, reportedly injured hundreds as it blew out windows and sent glass flying.
Actually a meteorite streaked across the sky and exploded over central Russia, raining fireballs over a vast area and causing a shock wave that smashed windows, damaged buildings and injured 1,200 people.
People heading to work in Chelyabinsk heard what sounded like an explosion, saw a bright light and then felt the shock wave, Chelyabinsk is an industrial city 1,500 km (950 miles) east of Moscow.
The fall of such a large meteor estimated as weighing dozens of tonnes and the size of a double-decker bus, was extremely rare, while the number of casualties as a consequence of its burning up around a heavily-inhabited area was unprecedented.
”While events this big are rare, an impact that could cause damage and death could happen every century or so. Unfortunately there is absolutely nothing we can do to stop impacts.”
to think of anything in recorded history when that number of people have been indirectly injured by an object like this… it’s very, very rare to have human casualties,” Robert Massey, deputy executive secretary of Britain’s Royal Astronomical Society (RAS), said.
Witnesses described feeling a pressure wave and hearing explosions overhead as the object hurtled to Earth.A wall and roof were badly damaged at the Chelyabinsk Zinc Plant but a spokeswoman said no environmental threat resulted.
The regional governor in Chelyabinsk said the meteorite shower had caused more than $30 million in damage, and the Emergencies Ministry said 300 buildings had been affected.
The office of the local governor said that a meteorite had fallen into a lake outside the town of Chebarkul in the Chelyabinsk region and television images pointed to a six-metre (20-foot) hole in the frozen lake’s ice.
Dozens of videos of the meteor trail and its aftermath quickly appeared online, and analyses of these eyewitness accounts as well as measurements from scientific instruments are giving scientists one of the best looks ever at an atmospheric meteor burst.
Many drivers in Russia have video recorders fitted in their cars in case of accidents or disputes with traffic police. Footage from these uploaded to YouTube show the fireball crashing to the ground.
Meteorite hits earth – What is the impact?
Illustration: THE RUSSIAN METEOR
The entry: A 7,000 tonne meteor entered the atmosphere above Chelyabinsk, Russia, at 9:20 a.m. local time at a speed at least 40,000 kilometers an hour, disintegrating at a height of 30 to 50 kilometers Researchers at NASA say it hailed from the asteroid belt between Mars and Jupiter.
The strike: The meteor unleashed a force 20 times more powerful than the Hiroshima bomb, although the space rock exploded at a much higher altitude. The fireball it produced was dramatic, causing a sizable sonic boom.
The fallout: An estimated 1,000 people including 200 children were injured. Many were hurt rushing to windows to glimpse the fireball, only to have the windows shatter seconds later. Shock waves from the debris are believed to have knocked in part of the roof and walls of a local zinc plant and damaged 3,000 other buildings.
::What was it made of?
“It is likely to be based on rock like what you would find on Earth.”
But may have contained some metals, such as iron.
::How big was it?
NASA has found this is the largest meteor since the Tunguska event in 1908, which flattened hundreds of acres of remote forest in Siberia.
The meteoroid was about 50 feet (15 meters) across before it entered Earth’s atmosphere, the space agency reported. That’s significantly smaller than Tunguska, which was about 130 feet (40 m) in diameter. It’s also about a third the size of 2012 DA14, an asteroid that made a close pass by Earth Friday afternoon, which is likely similar in size to the Tunguska object.
A 50-foot (15-m) diameter would make the Russian meteor larger than one that streaked over Indonesia on Oct. 8, 2009
::Did it have anything to do with 2012 DA14?
The arrival of the Russian meteor on the day of a close flyby by asteroid 2012 DA14 is just a weird cosmic coincidence. Videos of the Russian object show it traveling north to south, NASA has found. Asteroid DA14 is traveling south to north. The different trajectories reveal that the two space rocks are completely unrelated — other than reminding Earthlings that we live in a solar system full of flying shrapnel.
::How often does this happen?
Large meteor explosions aren’t a daily occurrence, especially over populated areas, but they do happen. Meteors of this size enter the atmosphere every few years to every decade or so, said Mark Boslough, a physicist at Sandia National Laboratories in New Mexico who studies impacts.
“It’s like shooting craps,” Boslough told LiveScience. “You can go a long time without rolling a seven, and then in a short period, you roll a few. That’s just the way random events work.”
::Why do meteors explode?
Asteroids are just chunks of rock, so what makes them so explosive? In a word: speed.
The kinetic energy, or energy of motion, of a speeding asteroid is enormous. The Russian meteor entered the atmosphere going 40,000 miles per hour (64,374 km per hour), Bill Cooke, lead for the Meteoroid Environments Office at NASA’s Marshall Space Flight Center in Huntsville, Ala. said in a NASA press briefing.
The chunk of asteroid or comet that caused the 1908 Tunguska event is estimated to have entered the atmosphere at about 33,500 mph (53,913 km/h).
The shock wave from an asteroid’s interaction with the atmosphere heats up the rock, essentially vaporizing it, Boslough said. The hot vapor then rapidly expands in the atmosphere, with explosive results.
“It’s just like TNT going off, only much more energy,” Boslough said.
::What would have happened if it had hit Earth?
Objects of that size rarely penetrate the Earth’s atmosphere but it could have got through in one piece had it contained more metal.
If it landed in its original form, this would leave a crater three times its size and a “quite substantial” blast which would emanate a large amount of heat transferred from the kinetic energy of the meteor.
“You would probably see considerable fatalities if it hit a populated area.”
::What’s the difference between an asteroid, a meteorite and a meteor?
The terminology surrounding near-Earth objects can be confusing. Here’s a primer: Asteroids are rocky objects in space, smaller than planets. They have no atmospheres, but do exert gravitational pull, sometimes orbiting one another.
Meteors are asteroids, comet fragments or other space objects that enter Earth’s atmosphere or burn up. If you’ve seen a shooting star, you’ve seen a meteor.
Meteorites are meteors that make it all the way to Earth’s surface. They’re tough to find. The staff of the American Museum of Natural History in New York fields multiple emails a day from people wanting to know if an odd rock they’ve found originated in space. In more than 17 years, only one of these supposed meteorites has panned out, a planetary science staff member recently told LiveScience.
::Can we see asteroids coming?
Russians weren’t expecting explosions in the sky on Friday morning. But there’s both good news and bad news about how much we know about dangerous space rocks .
The good news is that NASA researchers have calculated the paths of at least 90 percent of near-Earth asteroids more than 0.6 miles (1 km) across — the sort that could have a humanity-ending impact. [Top 10 Ways to Destroy Earth]
Smaller space rocks are more elusive, though. Astronomers have spotted only about 30 percent of asteroids 330 feet (100 m) wide that come near Earth during their orbits. Those asteroids could do a lot of damage if they entered Earth’s atmosphere. And only about 1 percent of smaller rocks like 2012 DA14 are known.
At about 150 feet (45 m) wide, 2012 DA14 and its ilk are three times the size of the rock that shattered glass and injured hundreds in Russia on Friday. The Russia asteroid approached the Earth from the daytime sky, NASA’s Cooke said. That made it invisible to telescopes, which can only search the night sky.
:: What can be done if we know a meteor or asteroid is going to hit Earth?
Scientists are constantly monitoring space for asteroids and meteors, and there are options to deal with them, including nuclear weapons.
But if the object is between 0.6 and 1.2 miles in size, it would cause a global catastrophe.”There are surveys going on to look for the larger stuff. It depends how soon you could pick them up.
“If you detect them early then we can contemplate deflecting an asteroid. As a very, very last resort you can always call upon nuclear weapons.
“And if everything goes wrong you do have the option to evacuate people.
“But if you get something between 0.6-1.2 miles in size then you are talking global catastrophe so evacuation probably wouldn’t do any good.”Read further
- What’s the Difference Between an Asteroid and a Meteor? (gizmodo.co.uk)
- Meteorite, Asteroid, Russia and the Big Difference (asccharlotte.wordpress.com)
- Know Your Terms: Shooting Stars, Dirty ‘Snowballs’ and Space Rocks on Earth (pbs.org)
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