Our Galaxy Has at Least 100 Billion Planets, Study Shows

http://www.jpl.nasa.gov/news/news.cfm?release=2012-010

by jfoucher • 15 years ago

96 48 15 years ago

jpl.nasa.gov

bitops• 15 years ago

Eric Idle already told us that quite a long time ago.

arethuza• 15 years ago

http://www.youtube.com/watch?v=buqtdpuZxvk

brudgers• 15 years ago

...and also that there is an infinity of worlds

Giordano Bruno beat him to the punch by four centuries (if of course one accepts 100,000,000,000 as a reasonable approximation of infinity).

http://www.positiveatheism.org/hist/brunoiuw0.htm#IUWTOC

huxley• 15 years ago

The "Galaxy Song" only specifies that there are a 100 billion stars :-)

For some serious geeky pedantry, it's hard to beat the Wikipedia entry for the song (especially the section entitled "Accuracy of figures quoted in the lyrics"):

http://en.wikipedia.org/wiki/Galaxy_Song#Accuracy_of_figures...

pessimist• 15 years ago

Hmm, "Our Milky Way galaxy contains a minimum of 100 billion planets according to a detailed statistical study based on the detection of three extrasolar planets by an observational technique called microlensing."

So we looked in 3 places, found 3 planets and are extrapolating to 100 billion? Surely I would wait for a few more examples?

Edit: Reading the full story, "Of the approximately 40 microlensing events closely monitored, three showed evidence for exoplanets. Using a statistical analysis, the team found that one in six stars hosts a Jupiter-mass planet. What's more, half of the stars have Neptune-mass planets, and two-thirds of the stars have Earth-mass planets. Therefore, low-mass planets are more abundant than their massive counterparts."

I dont get it. Any explanation?

mturmon• 15 years ago

The reason it's OK to extrapolate in this way would appear to be in this fact (from TFA):

"Unlike other prominent planet-detection techniques, which measure the shadows of planets passing in front of their stars (transit) or measure the wobble of a star due to the gravitational tug of a planet (radial velocity and astrometry), the gravitational-lensing technique is unbiased in the selection of the host star."

To know more, we have to read the story in Nature, which is here:

http://www.nature.com/nature/journal/v481/n7380/full/nature1...

Look at the error bars on their percentages. Super-earths (planets of 5-10x earth mass) are present on "62 +35 -37"% of systems. So, your intuition that the extrapolation was shaky is correct.

Retric• 15 years ago

Assuming the title and your numbers are correct they basically said. 'We estimate that there is a 95% chance that there are 250Billion stars +/- 60% which means there is a 97.5% chance that there are at least 100billion planets.'

However, the actual study costs US$32 so I am not buying it so somewhere in the game of telephone that we just played information could have mutated.

rokhayakebe• 15 years ago

I cannot even start to grasp the meaning of 100B planets.

I read that if the "Milky Way" was the size of China, then the the sun and 6 closest planets around together would be the size of one quarter.

InclinedPlane2• 15 years ago

I just did the math on that, it's about right. It's closer to a dime though.

thret• 15 years ago

If you really did the math, I love you.

cvg• 15 years ago

that's about one for every person that's ever lived.

karamazov• 15 years ago

very appropriate 2001 reference.

JeffL2• 15 years ago

Sounds a little more lonely when you read "it's likely there are a minimum of 1,500 planets within just 50 light-years of Earth." 1,500 isn't that many, and 50 light-years is a really long distance.

michaelcampbell3• 15 years ago

> 50 light-years is a really long distance.

Compared to what we can wrap our brains around generally, sure, but in the scheme of the universe, not so much.

meepmorp• 15 years ago

What about in comparison to a distance we'd be likely to reach before we annihilate ourselves?

celoyd• 15 years ago

We don’t really know how many 1,500 is, because we’re missing a lot of the variables we need to have even an order-of-magnitude estimate of how common intelligent life is. It could be practically inevitable on planets with liquid water; it could be one in a million even given “animal” life. Qualified experts disagree.

And 50 light years is a long distance to travel even at a tremendous speed like 0.01c, but it isn’t that long to send postcards. If we’d sent out a bunch of reasonably good questions in 1912, we would still be interested in the answers today. (More interesting, I think, is what they would ask us.)

In retrospect, I’m assuming we’re taking a finding-intelligent-life perspective here. But if you’re thinking in terms of human expansion – terraforming and so on – then I agree.

prawn3• 15 years ago

More interesting again is what they could tell us. I think with the time scales involved, chances are that anyone communicating with us would be significantly more advanced.

felipemnoa• 15 years ago

We are pretty isolated. Had we belonged to a cluster of stars our chances of finding life would have been greater.

From Wikipedia: http://en.wikipedia.org/wiki/Star_cluster

Globular clusters, or GC, are roughly spherical groupings of from 10,000 to several million stars packed into regions of from 10 to 30 light years across.

martey• 15 years ago

From http://en.wikipedia.org/wiki/Globular_cluster :

"However, they are not thought to be favorable locations for the survival of planetary systems. Planetary orbits are dynamically unstable within the cores of dense clusters because of the perturbations of passing stars."

malbs• 15 years ago

Some have theorized that the reason we are even talking about this is because we are _not_ in a cluster. We are pretty isolated, life ending events are pretty rare, every 60 million years?

michaelfeathers• 15 years ago

I'm just troubled by the fact that alien TV signals appear to look like static.

CamperBob• 15 years ago

This is unfortunately no joke. Only a fairly primitive technological culture will waste energy and S/N ratio by using coherent signals for communications. Modern radio and TV signals look more or less exactly like static to a receiver that doesn't know what it's listening to, for the same reason that a .jpg or .zip file looks like random data to a program that doesn't know how to decompress it.

So it seems clear that SETI-like efforts will be unlikely to detect any transmissions from civilizations who aren't deliberately trying to talk to us. Only civilizations that occupy the narrow time slice caught between the invention of radio and the widespread adoption of digital computers would be detectable, otherwise.

julian37• 15 years ago

This is very exciting.

On a related note, the number put forth by the study (at least one planet per star, on average) is roughly consistent with Drake's 1961 estimate that half of all stars will have planets, and stars with planets will have 2 planets capable of developing life.

Except, of course, that Drake estimated an average of >=1 habitable planets per star. Still, it's good to see one of his estimates being corroborated.

http://en.wikipedia.org/wiki/Drake_equation

microarchitect• 15 years ago

Drake just pulled a bunch of numbers out of a hat and multiplied them. This is a much more serious scholarly effort.

demallien• 15 years ago

Drake did no such thing. The Drake equation was not designed to give us an answer as to the number of civilisations out there, but to show us which questions needed to be answered to help us identify candidate search locations.

As an example, the Kepler mission is a direct result of the Drake equation, designed to resolve the first two parameters - fp and ne.

shaggyfrog• 15 years ago

The headline reads even better if you imagine Carl Sagan saying "billion".

rbanffy• 15 years ago

So, where are the other kids? We want to play.

johnnyg• 15 years ago

Now all we need to do is get each of them to send us $150. US debt crisis solved.

eru• 15 years ago

Where should they take the money from? You print all the dollars. Unless there's been trade with aliens, they won't have any earthling money.

Joakal• 15 years ago

I believe there are much more planets because not every planet has a star: http://www.dailygalaxy.com/my_weblog/2011/09/billions-of-dar...

ifearthenight• 15 years ago

Now I feel a bit of a loser for only having visited one so far.

Our Galaxy Has at Least 100 Billion Planets, Study Shows

Related Stories