How can we estimate the number of Earth-like planets in the Galaxy?
I'm doing a science project and i had to read a science fiction book and find the facts in it and it said that 100 billion stars in our galaxy and 10 percent of those starts have planets and maybe one percent of them have earth-like conditions. Is that true? And how can you estimate the number of stars with planets with earth-like conditions?
We do not have a very complete picture of how planets form around stars and how Earth-like planets form, although the basic idea is that they form from a disk of matter around a young star.
There have been a few observations of such disks around young stars and we know of about 100 extra solar planets (none are Earth-like).
From the basic idea and the small number of planets we have found we can make an educated guess at the number of planets that are really out there and the fraction of those which might be Earth-like. The numbers you quote sound OK, but should be taken only as a rough estimate for the reasons I gave above.
You might notice that these small fractions still give an estimate of 100 million Earth-like planets in our Galaxy alone, so the main point that you should draw from this is that since there are such a large number of stars in the Galaxy, even if it is extremely unlikely that a given star will have an Earth-like planet around it, there could be a large number of them overall.
Get More 'Curious?' with Our New PODCAST:
- Podcast? Subscribe? Tell me about the Ask an Astronomer Podcast
- Subscribe to our Podcast | Listen to our current Episode
- Cool! But I can't now. Send me a quick reminder now for later.
- Can the theory of formation of the solar system explain all the observables?
- Will the next generation telescope OWL be able to detect an Earth like extrasolar planet?
- Why is our solar system so different from all the others we've found?
- Which planet is most similar to Earth?
- Could there be life in the galaxies nearest to the Milky Way?
How to ask a question:
If you have a follow-up question concerning the above subject, submit it here. If you have a question about another area of astronomy, find the topic you're interested in from the archive on our site menu, or go here for help.Table 'curious.Referrers' doesn't existTable 'curious.Referrers' doesn't exist
This page has been accessed 32464 times since January 20, 2003.
Last modified: January 20, 2003 5:38:48 PM
Ask an Astronomer is hosted by the Astronomy Department at Cornell University and is produced with PHP and MySQL.
Warning: Your browser is misbehaving! This page might look ugly. (Details)