Let us remind ourselves of the definitions of the many objects flying around in space..
- Comet – a relatively small solar system body comprising ice and debris that orbits the Sun.
- Asteroids – are larger solar system bodies that orbit the Sun. Made of rock and metal, they can also contain organic compounds.
- Meteoroid – a small rock or particle of debris in our solar system.
- Meteor – a meteoroid that burns up as it passes through the Earth’s atmosphere.
- Meteorite – a meteoroid that survives falling through the Earth’s atmosphere.
The origin of meteoroids is thought to be small particles that break off comets and asteroids. They are defined by their size which range from smaller than a grain of sand to objects about 1 metre wide. They are incredibly numerous in our solar system as evidenced by the huge number of impact craters on Mars, the moon and other moons around planets. Here there is little or no atmosphere to break up the meteoroid.
Further evidence is that an astonishing 15,000 tonnes of meteoroids, micrometeoroids and space dust enter Earth’s atmosphere every year.
The composition of meteoroids ranges from fragile, low-density snowball objects to dense nickel-iron rich rocks.
When meteoroids hit our atmosphere they heat up and disintegrate into particles which we know as..
We are all familiar with the term ‘shooting star’ and have witnessed these streaks of light in the night sky. What we are seeing is the break-up particles of a meteoroid glowing as they streak though the atmosphere. Most completely disintegrate before reaching the Earth’s surface.
They can be quite spectacular as a single occurrance and multiple meteor showers. A particularly bright meteor is known as a fireball. The most famous is the Leonids a prolific meteor shower associated with the comet Tempel-Tuttel. This occurs annually in November and showers an estimated 12-13 tonnes of particles across the planet. Fortunately these particles are minute and cause no damage to us or the surface not like…
A meteorite is usually part of a larger asteroid or meteoroid that has survived the passage through the Earth’s atmosphere and impacts the surface relatively intact. They may or may not be associated with an impact crater.
Many examples of meteorites have been found on Earth over hundreds of years. The most recent findings occurred in Russia after one of the most spectacular meteors exploded just above the ground at Chelyabinsk showering a huge area with small meteorites.
The most concerning aspect of this meteor is that it originated from a 20 metre wide asteroid that arrived at Earth completely undetected.
Further evidence that space is a dangerous place and our own solar system contains billions of objects which could prove disastrous for our star mission right at the beginning of our journey.