Several thousand planets orbiting other stars have been found so far and some are "Earthlike.”
So far, almost all these planets have been found by detecting the slight dimming of their stars as they pass in front of them. They are tiny points of dark crossing almost-as-tiny points of light.
We can estimate their sizes and the distances at which they orbit their stars and even analyze their atmospheres. However, there is no sign of our being able to image them—yet. Maybe an array of optical telescopes in space would do it, but that won't happen for a while.
What would be nice would be able to actually go there and have a look.
In our space exploration we often hear terms like “deep space" and “outer space". Although our achievements in space exploration are things to be proud of, as yet we have scarcely stepped outside our cosmic backyard.
Men have walked on the Moon, our unmanned spacecraft continue to explore the Solar System and Mars is now populated by a growing number of our robots.
The two Voyager space probes have left the Solar System and are now moving out into interstellar space. However, to put all that in perspective, manned spacecraft have ventured maybe one and a half light-seconds into space. A light second is the distance light travels in a second, around 300,000 kilometres. The edge of the Solar System lies less than a light day away.
To get to the nearest star we need to travel over four light years. Sirius, that bright, blue-white sparkling star in the south during the evening at the moment, is more than eight light-years away. Most of the stars we see in the sky lie at distances of up to a few thousand light years. Our galaxy is 30,000 light years thick in the centre and about 100,000 light years in diameter. Such distances lie far beyond current technology.
For example, at the moment we can envisage building a spacecraft capable of reaching 100 kilometres a second. If we were to go to Mars, travelling at that speed, it would take 10 days or more, depending on the route. However, a trip to the nearest star would take almost 14,000 years.
In some science fiction stories, the crews of the spacecraft are deep frozen for the trip and revived just before arrival. That might work, but would your family, or even your country, recognize you when you arrive home 28,000 years later.
If we could achieve, say, 50% of the speed of light, that is 150,000 kilometres per second, it would still take eight years or so. Maybe we could be frozen for that long, but getting home a century after leaving would be a bit hard on most of us.
Going close to, or at, the speed of light raises other serious issues. At such speeds, time passes for the astronauts far more slowly than for the people back home. The closer to the speed of light we travel, the stronger the effect.
Travelling very close to the speed of light for a few years could mean by the time we get home, thousands of years could have passed.
At the moment, the stars are out of reach. We can only look at them. The distances between the stars have been called "God's Quarantine Regulations".
However, science fiction author Arthur C. Clarke said, "When an eminent scientist says categorically that something is impossible, he or she is almost certainly wrong".
Science fiction authors have come up with "jumps through hyperspace,” "warp drive,” and "space warp". It is true that at the moment we have no idea how to achieve such things, but as we increase our knowledge of what the universe is like, and learn more about the subtleties of space-time, maybe such developments cannot be ruled out.
Looking at the technical achievements littering our history, the idea that one day we could be orbiting a distant, Earthlike planet, and looking down at the surface of a truly alien world is not so farfetched.
• After sunset, Mars lies high in the south, with Venus and Jupiter low in the southwest amidst the fading sunset glow.
• The Moon will reach its first quarter on Feb. 27.
Ken Tapping is an astronomer with the National Research Council's Dominion Radio Astrophysical Observatory, Penticton.
This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.