|
So you're into sci fi? But what about sci fact? Sometimes fact
is stranger than fiction...
Each month our very own Voyager Science Queen* will bring you interesting,
quirky and downright bizarre tid bits from the world of science. And its all
completely, totally, 100% true!
September Sci-Facts
When is a star, not a star?
(Or, how to catch a falling star and put it in your pocket.)
|
I was wondering if you would explain how it is possible that micrometeorites are constantly raining down on earth, and that we don't live in a mud pit if this is so.
Yours Sincerely, Lavengro
Asteroid: a small rocky body orbiting the sun, occurring mainly between the orbits of Mars and Jupiter.
Meteor: a small body of rock or metal from space that enters the Earth’s atmosphere, becoming incandescent as a result of friction and appearing as a streak of light; also known as a falling star.
Meteoroid: a small body moving through space, being a potential meteor in the event of an encounter with Earth’s atmosphere.
Meteorite: a fallen meteor, of sufficient size to reach the surface of the Earth without burning up in the atmosphere. Meteorites are broadly classified according to their composition, over 90 per cent are rock while the remainder consist partially or wholly of iron and nickel.
All definitions are from
The Oxford English Reference Dictionary (Second Edition)
|
|
Every day the atmosphere of the Earth is bombarded by millions of meteors. Only a very small proportion of these are large enough to survive the intense heat of entry into our atmosphere, but every eon or so, a huge object impacts and leaves a crater.
Australia delights in approximately twenty impact craters and more are being discovered every year.
The most famous one is Wolf Creek Crater in Western Australia. It is considered to be the second most perfect crater known on the planet. It is about 900 metres across, with a defined rim of 25 metres. The original crater floor is approximately 150 metres below the rim, but time has been unkind, eroding this figure, and the floor has been partially filled in by wind-blown dirt and other debris.
These monstrous meteors are rare, and as previously mentioned, most meteors evaporate in our ionosphere.
But the ionised metals can condense again, much like water vapour can condense back into a liquid. Metallic ions derived from meteorites lurk in the E region of the ionosphere; the E region is where most aurora activity takes place. Lower down, in the cooler areas of our atmosphere, the metals can cool enough to form micrometeorites.
In their solid form, tiny, shiny spheroids, these micrometeorites then fall to Earth, as dust. They are considering highly collectable, and you can find them by running a magnet over the ground. The best areas are where the heavier gravels collect, washed down and sifted by the action of running water. Or, if you’re lazy, there are micrometeorites to be bought on eBay.
Meteor burst communication relies on the phenomenon of reflecting radio waves off the ionized trails left by micro-meteors as they enter the atmosphere and disintegrate. The huge numbers of these tiny meteors are enough to give usable trails.
All in all, there is more dust in the atmosphere than most people realise. It is this dust that creates the ‘seeds’ for raindrops, glorious sunsets, and ‘red’ snow in New Zealand. Most of this dust comes from pollution, volcanoes, or wind-collected ground soil, and a small proportion of this dust is formed by micrometeorites. A small proportion of the dust escapes back into space, driven by the tremendous forces of the weather in the atmosphere.
Even though millions and billions of meteorites strike the Earth’s atmosphere, they do not make an appreciable difference to the enormous mass of the Earth, even over geological time scales. So, we won’t be living in a cosmic mud pit any time soon, Lavengro.
|
*The Voyager Science Queen is also known
as Lynne Green
So, who is this woman who attempts to entertain us with Science?
Well, I really am a scientist. I have a Bachelor of Science degree from the
University of Queensland, in Zoology. And, at the moment, I am working in
a Pathology laboratory.
I have always been intensely curious about every aspect of our universe,
from the teeny tiny workings of the gene right up to the mind-bending forces
that are twisting and knotting inside a blackhole. So, now I am sharing a
brain stuffed full of trivia…and hopefully entertaining people at the
same time.
As well, I write Fantasy stories and novels. One day, I hope to have a book
published, but don't hold your breath. Reading is my other major love, and
my favourite authors are Terry Pratchett and Isaac Asimov, though I could
list hundreds of others. If I had one wish, I ask for more time to write!
Read previous Sci-Facts:
The Red Planet
Minerals
Hot Topic - Vitamins
A brief glimpse of New Technologies
Cuddly Australian Animals
Something light-hearted
Living in Interesting Times
New Hope for Our New Year
The Meaning of Life…
As the worm turns
Forensics
A Grab Bag of Facts
Bits and Bobs
Australian Achievements
Getting Your Attention
May Sci-Facts
After the Big Bang
The Big Bang
Ashes to ashes;
Dust to dust
Twists in the
tale
Robots in the
Swim and other things
The Tachyon and
other things
Looking for more scientific oddities? Have you checked out Dr
Steven Juan's website? He is, quite literally, the wizard of odds!
|
