A fireball that recently streaked through the sky north of Toronto may have released some small meteorites and researchers at the Royal Ontario Museum and the University of Western Ontario are seeking the aid of local residents in retrieving the space debris.
What can science learn from the fragments?
Five cameras set up in southern Ontario by the physics and astronomy departments at Western recorded the fiery descent of a meteorite (slow fireball) that recently appeared over Newmarket, Ontario (between Newmarket and Lake Simcoe, to be exact). Researchers estimate that the fragments may total a few hundred grams and are requesting help from the public in retrieving them.
It is indeed an uncommon occurrence for pieces of meteorites to be found because most meteoroids disintegrate when entering the earth’s atmosphere. This is not to say that some of them don’t reach the Earth’s surface each year because a few of them do, but in reality only a handful are ever recovered and made available to scientists to study.
According to Dr. Kim Tait, who is in charge of meteorite collection at the museum:
“Fireball fragments will give clues to the material in our solar system. We’re very excited about this fireball occurrence. Although this is not the first time a meteorite has fallen in Ontario, we are very interested in recovering fragments.”
The museum’s mineralogy department has requested that residents who discover fragments on their property contact the museum directly. Almost always magnetic in nature, meteor fragments are in no way dangerous to the human touch. They are usually black in color due to a fusion crust, which can be shiny or dull because its outer surface has been burned during ingress to the atmosphere.
A bit confusing, terms referring to meteors need some clarification. A meteorite refers to an object originating in outer space that survives an impact with the surface of the Earth. It is called a meteorite while still floating in space and becomes a fireball known as a meteor after it enters the atmosphere.
The pressure of impact causes the object to ignite, so to speak, forming a fireball or shooting star (or meteor, if you can’t make up your mind). If you are still in need of more clarification, consider the term, bollide, which can be either a body that collides with the Earth or a fireball-like meteor whether or not it impacts with the surface of the Earth.
Having almost as many aliases as a bank robber on the lam, a meteorite that has been recovered and observed as it impacts the Earth is called a Fall. All others are known as Finds. If this is still about as clear as mud, add the fact that meteorites are always named for the place they were found.
If there are a few of them found in a specific location, a number or letter to differentiate it might follow the name from the others. Some meteorites have informal nicknames, such as the Sylacauga meteorite, which is also known as the “Hodges meteorite” after Ann Hodges, the woman who was struck by it.
Meteorites generally fall into three broad categories: stony meteorites, which are rocks mainly composed of silicate minerals; iron meteorites formed from metallic iron-nickel; and, stony-iron meteorites, which contain large amounts of both metallic and rocky material. About 86% of the meteorites that fall on Earth are in the first category and are known as chondrites, so named for the small, round particles of silicate minerals they contain. Chondrites are believed to be about 4.5 billion years old and are often considered to be “the building blocks of the planets”.
The heating of meteorites during their passage through the atmosphere melts their surfaces and they can then be “sculpted” into various shapes. If the meteoroid maintains a fixed orientation for some time, without tumbling, it may develop a conical “nose cone” or “heat shield” shape. Those that experience disruption in the atmosphere may fall as meteorite showers, which can range from only a few up to thousands of separate fragments. The area over which a meteorite shower falls is known as its strewn field.
Large impact craters are rare as few meteorites are big enough to create them. Usually, they arrive at the surface at their terminal velocity and, at most, create a small pit. Even so, falling meteorites have reportedly caused damage to property, livestock and people.
What secrets will the research team in southern Ontario discover? Only time and the integrity of its local residents may tell.