Hi and welcome my space related page. I have a strong interest
in space related things and always have ever since I can remember.
Here I have written some interesting articles and included some interesting
facts. I am currently looking to include more links to space related
sites on this page so let me know if you know of any and I will include
65 million years ago the Earth was believed to
have been struck with a comet or asteroid that nearly destroyed all life
on the planet and if it were much bigger may have knocked us out completely.
Scientist have found a huge impact crater near the coast of Yucatan, Mexico measuring 200 km in diameter and matching the age needed to have occurred at the same time as the extinction of the dinosaurs. So what you say this theory has been around for some time.
Well yes it has but when you think about it you can start to ask some pretty profound questions. For one thing it has proven that it is possible for an asteroid or comet to hit the Earth and profoundly change the environment. This impact is believed to have spread an ejecta across the immediate area and into the atmosphere causing dust clouds that obscured the sun for years after the event. This would have caused a decade long below zero temperature spell for the entire globe followed by a time of reduced sunlight.
Eventually both from the immediate impact and the environmental effects over 75% of all life on the planet was destroyed. That is the Earth was almost sterilized completely. Luckily some species survived including mammals that were well suited for the cold.
This asteroid or comet was predicted to have been between 10 to 15 km in size when it hit. Not so big really when you consider there are many more asteroids of at least that size floating around out there in space. It is estimated it would take only a 2 to 3 km sized comet or asteroid collision to push us to the brink of extinction today. Now hundreds if not thousands of such bodies and bigger have been discovered many with orbits that cross the Earths.
For example the famous Tunguska event almost 90 years ago flattened a vast forested area in Russia. It is believed to have been a comet that approached and exploded in the atmosphere causing a huge shock wave that caused the damage. Luckily this occurred in an unpopulated area and noone was injured. If it had happened over New York it would have been quite a different story.
It is quite possible that some kind of extra terrestrial body like a comet or asteroid is orbiting in space with our name on it. However it is a relatively rare event for a collision to occur. There have been many close calls though including a near miss back in 1986 when an asteroid passed by as close as twice the distance of the Moon. Quite safe really but still close enough to be noticed.
NASA is spending great amounts of resources to combat the threat of a collision and has a good program to detect any asteroids or comets before they get anywhere near us. But one never knows where the next impact object will be lurking and we may never know of it until it is right on top of us.
Mars and Martians
By now I am sure you have heard of the so called
bacteria found in a martian meteorite. It was widely published in
the media and proclaimed to be proof of life on Mars. So was it?
Well to answer that question you must first understand a few things about
the meteorite and Mars itself.
Firstly the meteorite is most likely to be from Mars due to its chemical composition, secondly as it entered the atmosphere it was sealed by frictional burning of its outer layers meaning no Earth bacteria could have entered the rock. Also the type of bacteria is a very specific type most closely resembling the so called nano-bacteria that are found deep underground on Earth.
Scientists were at first a little puzzled because the bacteria like fossils found in the Martian meteorite seemed to display very life like qualities both chemically and physically but they were too small. Then they hit upon where the bacteria came from nd found it was most likely from underground on Mars. On Earth we have very small bacteria that live underground called nano-bacteria and scientist speculated that the Martian fossils may be a form of similar bacteria that once lived on Mars.
To fully understand if life ever existed on Mars you have to look at the planets history. Today Mars is a dry barren desert world with large ice caps and virtually no atmosphere. However in the past Mars may have been dramatically different.
Several features on Mars indicate a more interesting past. One there are huge canals or channels that wind around on the surface of Mars looking rather like dry river beds, secondly there are huge extinct volcanoes on Mars and also evidence of what would seem to be water erosion.
Those volcanoes were probably active as little as 2 billion years ago and definitely would have produced huge amounts of gas and dust filling the Martian atmosphere with a density that could sustain liquid water on the surface. Evidence of liquid water having once flowed on the surface of Mars comes in the form of canals or valleys that wind all over the planet and show strong evidence of past erosion by water. If liquid water existed on the planet then Mars would have to had been warmer than it is today at least above 0 degrees Celsius.
If Mars was that warm it would have needed a thick atmosphere to keep heat around the planet. This atmosphere would have been produced by some kind of volcanic activity meaning it would have been high in carbon dioxide gas. Carbon dioxide is a greenhouse gas and traps heat very well. All these things point to Mars being rather warm with liquid water on its surface. In fact there is enough liquid water in the Martian poles and permafrost to completely cover the surface of Mars by two centimeters.
Mars was probably a tropical paradise in its youth however the volcanism on Mars stopped and the atmosphere no longer able to be replenished began to thin. As the atmosphere thinned the temperature of Mars dropped, the poles grew as water froze out onto the Martian poles. The oceans evaporated and froze as permafrost and ice at and near the poles. Effectively Mars died.
It is questioned weather Mars evolved life during its youth when it was to all purposes rather Earth like. The general idea is that it was more than likely that something began to evolve on Mars even if it was only simple bacteria life may very well have started on Mars only to be cut short when the Volcanism stopped about 2 billion years ago.
The bacteria may have survived deep underground for quite some time after Mars had effectively died and some scientists speculate that some bacteria may still be living near the martian poles feeding off the ice and soil.
The question of life on Mars is not an easy one. Those Martian fossils in that meteorite may present scientists with more questions than answers. Questions that are driving people to seek to explore the red planet and discover its many hidden secrets possibly even finding new life or at least understanding how life evolves and what went so wrong to turn Mars from its infant paradise into a modern frozen wasteland.
If you know of any good astronomy
related sites let me know the URL and I will consider linking it here.
Naturally I will add more links in time but these three are pretty good
and worth checking out especially the NASA site it is very big and full
of news, images, articles and more.