how many other planets, do you think?

Question

then are there like a million other planets out there? think of all the stars... are those suns for some planets? and if we are only in the milky way, then does that mean that there are other places that there could be living beings?

Answer 1

You've awakened the starry-eyed dreamer in me at this late hour! I should be sleeping, but can't resist your question.

How many other planets, do I think? Actually my number is a lot higher than millions! In fact, on this subject you get into numbers so large that most of us humans cannot relate them to anything in our experience. So, sadly, I doubt we can appreciate the grandeur of the universe. But let me try...

One fairly recent estimate says there are 70 sextillion *visible stars* in range of modern telescopes (70,000 million million million).

To help put that in perspective, I'll use a rather old but useful analogy. Imagine scooping up a big handful of sand at the beach. Try counting the grains of sand. You'll give up, most likely, in seconds, assuming you even bother to try. Now look all around you on the beach, and think about *that* number. Now think about all the grains of sand on *all the world's* beaches... and deserts. Now multiply that total number by ten, and you get approximately the number above -- of stars in the *known* universe. The stars not visible to us by even our most powerful telescopes may equal the visible figure -- or be multiples of it. Mind-boggling, no?

So to your planet question: One next has to wonder how many of those stars are actually a sun to one or more planets (hey, I just noticed that was your wording, too; I like it). Does every star have at least one planet revolving about it?

Well let's just be very conservative and say that there are only 70 sextillion stars in the *entire* (not just known) universe. Let's further say that only one tenth of those stars (7 sextillion) have a planet orbiting them. If we assume merely one planet per sun, then there must be at least 7 sextillion planets in the universe. Using our sand analogy, that's a planet per grain of sand on all the world's beaches and deserts!

Anyone who believes that is a reasonable number must surely wonder, "How could there NOT be living beings somewhere other than the earth?"

Of course not all planets will have life on them. Earth may be the only body in our solar system, for example, which does harbor life, though at least one of Jupiter's moons is also a tantalizing possibility.

If only one out of a *thousand* of those planets are earth-like -- in the sense that they are rocky, not gaseous, and contain liquid water -- there may be 7 quintillion earth-like planets in the universe. That's 7,000 thousand trillion. I've been very careful, but if my math or estimates are off by even a factor of a *billion* there could be 7,000 million earth-like planets in the universe, a figure I think is extremely low.

These figures seems to jibe fairly well with an estimate of the number of earth-like planets in our galaxy alone, found at space.com (the bottom link in my sources) -- 30 billion, from a 2002 article.

My personal belief, based on numbers such as this, and on the likelihood that any planet supporting life may contain (extremely conservatively!) a thousand species... is that there are *billions* of intelligent species in the universe outside the earth.

Since you were wise to point out that we reside in the Milky Way galaxy, which is only one of perhaps billions of galaxies, you might be fascinated by the Hubble photo in the references, below. I liked it so much, myself, that I made it my new desktop wallpaper.

Finally, on the specific subject of life, there is a well-known method of estimating the number of intelligent, communicating civilizations, called the Drake Equation. In my references you can see how it works to condense all the possible stars down by multiple factors, leaving the fraction which we may be able to communicate with, or at least hear from!

Happy dreaming (for me, too), and I hope you are as inspired by all this as I am. :-)

Answer 2

Lots of questions, you have! Answer them, I will try. Yes, there are other planets out there, probably too numerous to count -- we've already detected and catalogued a whole bunch, although with our current technology, we can only see things larger than Saturn or Jupiter, so finding an Earth-like planet will be a while. It is assumed that there are probably more stars out there that have planets orbiting them than those without, though the conditions on any one of them may very well be beyond our ability to imagine. As for life... we just don't know, but to paraphrase the great astronomy populizer Carl Sagan, out of billions upon billions of stars, and out of all the planets that must orbit them, the idea that we are so special here in our tiny, insignificant little corner of it that we are the only planet in the universe to have developed life is not only arrogant, but patently ludicrous.

Answer 3

They have proof of planets in other star systems. Most of the planets that they have discovered are huge planets like Saturn and Jupiter, but they are getting better at finding them I think earlier in the spring they found a planet that was 6 or 7 times the mass of earth and that is pretty small compared to Saturn.

There are a lot of theories as to where to find these planets, so that should help in finding them. I think that it would be pretty cool to walk on another planet that has an earthlike atmosphere.

Answer 4

Infinite number of planets. Not all stars will have planets but there are enough that we are finding new planets around other stars very often. The Seti project is currently searching for other civilizations. Statistically, if is illogical to think we are the only life in the universe.

Answer 5

From what I've read and watched in documentaries, whether it's possible that other living beings could inhabit another planet somewhere out there afar, we don't know. It's more likely that when we speak of finding life on another planet, that the life being referred to is on a molecular or germ level, rather than recognizable life as we're accustomed to. At least that's what I get from news on such things.

Answer 6

definetly, there are billions of planets and stars. But what are the chances of us actually contacting and finding life? I honestly don't know but what I do know is that traveling out of our galaxy is not going to happen anytime soon. Let me put it this way the nearest star other then our sun is 4.4 lightyears away that is it takes light 4.4 years to travel from there to us. To translate, if we were to be ina spaceship it would take us 4.4 years to get there if we move at speed of light which is not going to happen therefore in reality it will take us alot more time. Life in the universe is possible but chances of us discovering it anytime soon (or it happening in our lifetime) is very rare.

Answer 7

billions if not trillions

Answer 8

We are not alone!