Last year using a somewhat restrictive method of detecting exoplanets (planets outside of our solar system) scientists estimated that there were 50 billion in our galaxy. Using a more sensitive method they have just estimated that there are 100 billion. Moreover, per the article:


From this analysis, the PLANET team made a rough estimate of 100 billion exoplanets living in our galaxy. Additionally, they found that one-in-six stars host a Jupiter-mass exoplanet, half the stars in the Milky Way have Neptune-mass exoplanets and two-thirds of the stars have Earth-mass worlds. Interestingly, this result points to least 1,500 exoplanets within 50 light-years from the solar system.


The findings are to be published in the January 12, 2012 issue of the journal, Nature. 

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Astounding numbers for just one galaxy---added to which there are billions if not trillions of other galaxies. 

John Jubinsky

This is a very huge number indeed and indicates the mind boggling size of only our galaxy. I believe that the number of stars in our galaxy is also of similar order. If this is true, isn't the number of planets somewhat less? Is it likely that many more planets are likely to be in the process of formation?

I don't know whether there should be more planets or more stars in the Milky Way. At any rate here is a brief article on the number of stars in it. According to the article there are 200 to 400 billion stars in it.

Here too I have a doubt. Planets are said to be born within the protoplanetary discs formed around stars. If a protoplanetary disc can create one or more planets, then, on an average, there should more than one planet per star. Am I right in my assumptions?

I certainly know that stars commonly have multiple planets. Because stars can have multiple planets I was careful to say that I don't know whether there should be more planets or more stars in the Milky Way. I think the scientists are conducting their tests and using their rationality according to the best technology they have. However, just last year they estimated only 50 billion planets in the Milky Way and already they have estimated twice that number. As they develop new approaches to estimating the number their estimate might jump upward again. At this point I think it is safe to say that their 100 billion estimate is conservative.


Planets are not self iluminating like stars and so it must be more difficult to observe them. This could be one reason why less of them are found.

He can't be blamed for creating them. He is simply a god, you know. How he could have done it?

Why do you doubt him? How the poor fellow could have done it? He didn't even know Einstein's relativity!


What do you mean by????  Couldn't you undrerstand a bit of humour????




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