any rate, the possibility that some alien civilizations are much more advanced than us is very good. If so, perhaps they have visited the Earth during our history or are doing so now. Just because we have no incontrovertible evidence they are doing so is not proof they are not doing so.
By definition, aliens will think and act in alien ways, beyond our comprehension and understanding. Maybe we simply cannot detect their existence because of some peculiar characteristic of their spacecraft.
There is a great deal of modern scientific research and brilliant deductive studies in the emerging field of exobiology: life outside of the Earth. Hardly a month goes by without more analyses being completed on another sample of Martian soil or rock in a quest for evidence of extraterrestrial organisms. The duplication of amino acid formation in the early stages of Earth’s history has convinced many scientists that life would likely arise on other planets and produce creatures somewhat similar to ourselves.
We know with a high degree of certainty that other human-like creatures do not exist elsewhere in our Solar System. Speculation is rampant that primitive lichens and bacteria may exist on Mars, in Venus’ atmosphere or perhaps even on a large moon of Jupiter or Saturn. Regardless, our local star system has been more or less eliminated for extraterrestrial life, based on our knowledge of what conditions are necessary for life to be viable, such as heat, light, water, etc. Where else might it occur?
UFOS AND ALIENS IN LITERATURE
The term Martian conjures up images of bug-eyed monsters, many-tentacled monsters and evil aliens, all intent on doing us in, but also a black-headed cartoon character who battled Bugs Bunny in several shorts and features. As well, Edgar Rice Burroughs, creator of Tarzan, wrote a series of space romance novels in the early 1900s in which American John Carter travelled to Mars only and battled many strange creatures, often necessary to rescue maidens in distress.
On a clear night, you can see only about 5,000 of the billions of stars in the universe. The rest are too far away and their light is too dim to be seen by us here on Earth. Some of these stars are physically very close to us and can be called our neighbours, even though they are still trillions of kilometres away!
The nearest star system to us is the Centauri triplet of stars right next door, only 40,621,000,000,000 kilometres away! That’s about 4.3 light years in astronomical terms; it takes light waves more than four years just to reach us from those stars.
The nearest of all other stars is Proxima Centauri. It’s a dim, red star that orbits the pair of stars known as Alpha Centauri A and Alpha Centauri B. These three stars perform a kind of cosmic waltz with one another, with Proxima dancing by itself while revolving around the two others of the trio. Proxima is about 4.2 light years from us, while its companions are 4.3 light years away. Alpha Centauri A is the same colour as our Sun, which means it is about the same temperature as the Sun. All things being equal, it might be able to support planets like Earth and sustain life.
WHAT IS A LIGHT YEAR?
Distances in space are measured not in miles or kilometres, but in light years. One light year is the distance that light travels in one year. Although light seems instantaneous, it actually takes time for it to travel great distances. The speed of light is 300,000 kilometres per second.
For example, since the Moon is about 376,000 kilometres away from the Earth, light takes a little over one second to travel between the Earth and Moon. The sun is much farther away, and light takes about eight minutes to reach us from its surface. But other stars and galaxies are much farther away, and light takes many years to travel that far.
However, with three stars orbiting around one another, the mechanics of planetary formation are complicated, so stable orbits for small planets may be difficult. But the two main stars of this system are a considerable distance apart, about the same as the distance between Earth and Uranus, so there may be stable orbits for planets close in to their stars.
In the movie Avatar, this is exactly what has happened, and one of the large gas giant planets orbiting Alpha Centauri A has a moon named Pandora that is inhabited by the mysterious blue creatures named Na’vi.
Next out is Barnard’s Star, named for Edward Barnard of Lick Observatory in California, who discovered it in 1916. It is a dim, cool star like Proxima Centauri and is the closest nearby star that can be seen from the northern hemisphere, in the constellation Ophiuchus. Although it is about six light years away, it’s getting closer to us, zipping through the galaxy at such a rate that it will come closer than Proxima Centauri in about 11,000 years, then move off again into deep space!
Wolf 359 is yet another small red star, this time in the constellation Leo. German astronomer Max Wolf measured its movement and listed it in a catalogue in 1917. More than seven light years away, it’s very faint and is actually one of the coolest stars known. Any planet orbiting this star would have to be very close to it in order to get enough heat and light to support any kind of life.
OUR NEAREST NEIGHBOURS
1. Proxima Centauri
2. Alpha Centauri A
3. Alpha Centauri B
4. Barnard’s Star
5. Wolf 359
6. Lalande 21185
7. Sirius A
8. Sirius B
9. Luyten 726-8 A
10. Luyten 726-8 B
11. Ross 154
Other planetary systems may have more than one sun in the sky. This artist’s conception shows what the sky might look like on a planet orbiting within a three-star system. Could such a planet support life?
Lalande 21185 is in Ursa Major, better known as the Big Dipper. It was first catalogued by French astronomer Jerome Lalande in 1801. Although it’s much brighter and hotter than the previous few stars in our list, it’s not as warm as our Sun. Even though it is a bit more than eight light years away, astronomers have been able to detect a planet around it and it may have more. Could life have formed here?
Sirius, the Dog Star, is in the constellation Canis Major, more than eight-and-a-half light years from us. It is the brightest star in our sky, blue-white in colour and very noticeable when it is shining in the night, often casting shadows on Earth. It’s about twice the size of our sun but much, much hotter. It might be possible for life to form on a planet in orbit around it, but it would complicated by Sirius’ companion star, Sirius B, which is a much smaller star — a dwarf star — that is only about the size of Earth but is made of very dense matter. A milk jug filled with this kind of matter would weigh as much as a four-story building on Earth. Could life form in this two-star system?
Luyten 726-8 A and B are two small stars in the constellation Cetus, and are nearly nine light years away from Earth. They were discovered by Willem Luyten, a Dutch astronomer, in 1948. They are also “red dwarf” stars but have a distinctive characteristic that may make them unfit for sustaining life: they
