A Thousand Planets
Sometimes science news brings one up short with wonder about the things we have discovered about the Universe.
A science programme broadcast on the BBC this evening reported that the number of extra-solar planets discovered has passed the thousand mark this week. (Wikipedia says that it the number was a thousand and ten as of 22nd October 2013.)
It is only about 21 years since the first confirmed discovery of a planet orbiting a star other than our sun. At that time the only extra solar planets we could discover were supergiants (planets like Jupiter) because they are big enough that both the planet and it's sun orbit around a common centre of gravity.
This in turn causes a slight doppler shift, "upwards" (higher frequency, meaning the light of the star is slightly more blue) when the star is moving towards Earth, alternating with a doppler shift "downwards" (lower frequency, more reddish light) when the star's orbit carries it away from earth. Human instruments have been able to detect such shifts since about 1988 and since the early 1990s a gradually increasing number of stars have been confirmed to have planets. As telescopes have continued to improve, and wtih the advent of the Hubble Space telescope, more and more planets have been discovered, some by other methods such as spotting the miniscule drop in a star's brightness when a planet passes between us and that star, and even in a few cases direct observation.
It will be many years before a human, or anything built by humans, could reach another solar system. However, one of the suns which appears to have at least one planet (though scientists are still debating the point) is Alpha Centauri B in the nearest star system to this one, four light years away.
We live in an amazing universe. We should not be ashamed to take time to wonder at that universe - or to take pride in how much we have managed to learn about it.
A science programme broadcast on the BBC this evening reported that the number of extra-solar planets discovered has passed the thousand mark this week. (Wikipedia says that it the number was a thousand and ten as of 22nd October 2013.)
It is only about 21 years since the first confirmed discovery of a planet orbiting a star other than our sun. At that time the only extra solar planets we could discover were supergiants (planets like Jupiter) because they are big enough that both the planet and it's sun orbit around a common centre of gravity.
This in turn causes a slight doppler shift, "upwards" (higher frequency, meaning the light of the star is slightly more blue) when the star is moving towards Earth, alternating with a doppler shift "downwards" (lower frequency, more reddish light) when the star's orbit carries it away from earth. Human instruments have been able to detect such shifts since about 1988 and since the early 1990s a gradually increasing number of stars have been confirmed to have planets. As telescopes have continued to improve, and wtih the advent of the Hubble Space telescope, more and more planets have been discovered, some by other methods such as spotting the miniscule drop in a star's brightness when a planet passes between us and that star, and even in a few cases direct observation.
It will be many years before a human, or anything built by humans, could reach another solar system. However, one of the suns which appears to have at least one planet (though scientists are still debating the point) is Alpha Centauri B in the nearest star system to this one, four light years away.
We live in an amazing universe. We should not be ashamed to take time to wonder at that universe - or to take pride in how much we have managed to learn about it.
Comments
Alpha centaui is not just a star, its actually 3 stars, that make up a single system. Many stars are binary (two stars really close and orbiting each other).
anything sad about the alpha centari system? - yeah, firstly it can only be seen from the southern hemisphere which is a shame.
whilst we have never built anything that has entered another solar system, we have built something that has left ours, Voyager 2. Voyager 1 will do the same thing next year
Voyager 1 and Voyager 2 are both on courses which will take them within a couple of light years of nearby stars in about 40,000 years' time.
We have not yet sent anything towards Alpha Centauri. I hope this is done soon (e.g. in the next couple of decades). I know I will never live to know what's over there but I would like my great-grandchildren to.