My day job, believe it or not, is to hunt for aliens -- just like in the movie "Contact". I'm also the host of the "Big Picture Science" radio show, produced right here at the SETI Institute in lovely, glamorous Mountain View, California. I'll be around for at least the next 2 hours to answer questions about astronomy, SETI, or what you should do if gray guys from another stellar system haul you out of your bedroom.

EDIT: Verification!/SethShostak EDIT2: Well, I gotta go feed the pet muskrats. It's been fun, and we'll do it again soon ... if you want!

Comments: 531 • Responses: 57  • Date: 

vkazemi75 karma

What are the chances of aliens living in our galaxy? and based on our current knowledge of Physics, do you think is it possible for a human/alien to ever travel to another galaxy?

sshostak162 karma

Our galaxy has roughly a trillion planets. Hard to imagine that they're ALL sterile.

Traveling between galaxies is hard ... typical distances are millions of light-years. That's a trip that, even with our fastest rockets, would take longer than the current age of the universe. That's a long time to be sitting in the middle seat ...

vkazemi27 karma

Can you give us an idea of how many of these trillion planets are perhaps suitable for life, and how much do we know about them?

sshostak97 karma

We know nothing about the overwhelming majority, but NASA's Kepler telescope will tell us what fraction are habitable ... and it's not unreasonable to assume that the fraction will be somewhere between one in a thousand and one in ten. Even with the pessimistic number, that's still a billion habitable worlds ... just in OUR galaxy.

flyingvader73 karma

Why do most aliens land in the US?

sshostak142 karma

I think this is an EXCELLENT question! It could be the superior fast food in this country. Mainly, however, it's likely to be the fact that one-third of the American populace believes that aliens are visiting ... and hey, if they're here, they're not going to be spending all their time in Lower Moldavia.

hhhnnnnnggggggg17 karma

For the Bunny Ranch

sshostak62 karma

Bunny ranch? Is that a kind of salad dressing?

hhhnnnnnggggggg10 karma

Legal Brothel.

sshostak63 karma

Glad to hear it's legal.

[deleted]62 karma

How can I get a job with you guys? I'll do anything.

sshostak100 karma

Well, the real problem is ... lack of money! We're not hiring too many folks these days ... which is a real shame.

Thereminz20 karma

I want a job there too. Any extremophile biologists need an assistant?

sshostak48 karma

Hey, if you're in school, apply to NASA's REU program. If not ... well, write an astrobiologist.

smooshie58 karma

If you detect an anomaly of some sort, how do you determine whether it's an alien signal, or something more mundane like a human satellite or computer error?

And thanks for the AMA :)

sshostak76 karma

Good question. First, we look at some of the signal characteristics to see if it's just a transmitter bolted to the Earth, in which case we can throw it out. But the real test is to move the antennas around a bit, and establish that the signal's coming from one spot on the sky, that moves across the sky at the same rate as the stars.

daBedroomIntruder49 karma

Is lack of funding a huge problem? Are you concerned for the future or are their new opportunities and advancements to look forward to?

sshostak339 karma

Huge. There may not be enough money for me to finish this sen

flyingvader42 karma

How far away could aliens detect our radio signals if they had the same technology that we have today?

sshostak56 karma

Not very far. In fact, not even the distance of the nearest star for many signals (such as TV). But our radars ARE very powerful, and could be found with technology analogous to ours from tens or hundreds of light-years distance.

VanBuren2235 karma

What kind of procedures are in place if contact is made? What steps take place once you can verify that the source of a signal is not terrestrial? Also, are you allowed to just run around screaming you found life, or does Uncle Sam put a lock down on it?

sshostak47 karma

No lock down. We KNOW this from false alarms. We do every test we can think of to determine if a signal's extraterrestrial ... including calling up someone at a different radio telescope, and asking THEM to confirm the detection.

Moon-Base30 karma


sshostak42 karma

Could be, but habitats in orbit might be easier to build and supply.

lighthaze30 karma

Been having your book on my amazon wishlist for a long time now. Now i'll finally buy it! Thank you for your work and being here!

sshostak40 karma

Thank you, thank you, thank you!

dcoats8627 karma

I want to thank you for inspiring me to go back to school; it was AWA/BPS that reminded me that if you do something you enjoy, you will never have to work a day in your life.

As for questions: 1. I've heard of using spectroscopy to determine elements in clouds of stuff out in space; would it be possible to see atmospheres on planets, and if so could one determine if there were strange chemical processes going on? 2. How much do you like your day job? As in, do you find astronomy and science communication rewarding? 3. You talk a lot about sci-fi flicks from yesteryear, do you have any favorite sci-fi books or short stories?

Thanks again.

sshostak33 karma

Terrific ... a listener to "Big Picture Science". Yes, spectroscopy HAS been used to look at the atmospheres of a few planets. With a space-based telescope, you could find things like oxygen and methane ... and find pigs in space! My day job's great. Except that it often extends into the evenings! And I'm painfully ignorant of written sci-fi. I know only about the really cheesy sci-fi flicks!

hopeforrobots24 karma

I'll let the more scientifically inclined redditors keep asking the interesting questions. What I really want to know is what kind of snack/beverage you prefer to consume during countless hours of data analysis and signal observation.

sshostak43 karma

What kind? The unhealthy kind, that's what! But actually, all the tedious stuff has been automated.

I will admit that the Institute recently installed some vending machines a 30 second walk from my office. I wonder if they have Corn Nuts?

brit_in_LA23 karma

Do you think its possible that we might see some odd astronomical sighting that would prove there was ETI?

sshostak37 karma

I do! It may be that we find our first evidence of ET by the accidental discovery of some mammoth astroengineering.

joshmyer23 karma

Have you guys ever considered making a little housetop dish+sensor that people could buy, install, and connect to the internet as a remote receiver that you'd control as part of a large grid? (It could include some "profit" in the purchase price to help fund the system, and perhaps be linked to an on-going pledge.)

sshostak31 karma

Harder to do than you think ... in particular, you need the high spectral resolution receiver behind the whole thing. The dish is actually the cheapest part of the operation ...

brit_in_LA21 karma

Any thoughts about how the religious leaders might react to a true ETI signal? ie how would the Catholics, Muslims and nutty right wing Christians react?

Texas would probably not allow it in their textbooks...

sshostak30 karma

Mainstream theologians would not be dismayed by this. Fundamentalists would have a harder time ... because descriptions of aliens are not found in scripture.

Can't speak to the reaction of Texas. Oklahoma, on the other hand ...

pbang20 karma

How often do you guys get all excited from signals such as the "wow" signal? Do ever prank each other with such things? I'm guessing trolling happens daily.

Also, I always had a question about the SETI @home project: how much error correction or error checking was done? If I recall, I was on dial up whe. I ran the screensaver. If my computer downloaded authentic alien data from you guys, then never reconnected to upload the findings, is t possible that I royally screwed up our only chance of being contacted? (or was the same data sent to multiple users)

Thanks bro.

sshostak45 karma

SETI@home's not our project. It's run by the guys at the Univ. of Calif. at Berkeley.

Exciting signals? Once every few years. Not much pranking, I'm afraid ... Too bad, as it would probably be educational!

pbang35 karma


sshostak68 karma

That's a signal comment!

Sushi_K17 karma

Do we really want to contact an alien civilsation? What I'm getting at is, if you look at how our own western civilisation has dealt with other societies in the past, how can we be sure that we won't be conquered by a more advanced civilisation soon after forst contact?

sshostak41 karma

No one knows if they'd be white hats or black hats. But whether we want to or not, evidence of our presence is now flying out into space. Not just our inadvertent transmissions like TV and radar, but things like the light from our cities. My advice? Don't lose sleep.

justinxduff13 karma

How ridiculous do you find the Planet X/Nibiru "theories" that are floating around the Web?

sshostak35 karma

I wouldn't give this any credit. If Nibiru existed, we would both see it and know its orbit ... not to mention being aware of the disruption of orbits in our solar system. But those disruptions are not there.

boogiemantm13 karma

Hi Seth! Big fan of you and SETI. Thanks a lot for all your hard work!

My question gravitates around Kepler. How has Kepler changed SETI? Has it had a huge impact on your strategy for finding E.T.?

sshostak21 karma

Well, obviously we look at the Kepler candidate planet systems. I think the big impact will be when Kepler finally tells us what fraction of stars have habitable planets. If that's a reasonable fraction (more than one in a thousand), then we can just look at almost all stars with confidence.

BishopOfThe90s10 karma

What do are your thoughts on the nature of potential contactees/extraterrestrials? Do you think they would really want to? Might they use a technology advanced beyond the use of radiowaves? Is SETI is more geared towards accidental contact?

sshostak16 karma

All of this depends on some things we don't know, such as (1) the motivations of aliens, and (2) their technical level. But I would bet on a deliberate signal ... easier to find.

BishopOfThe90s6 karma

I see! Thanks! I guess I will just hope that if they are sufficiently advanced enough to contact US, they would also be advanced enough to have no interest in killing us all for our resources.... Unless you have reason to believe otherwise?!?

sshostak44 karma

Hey, we don't have any resources THEY don't have ... other than our culture. Maybe they'd come here for the reggae ...

UncleMatthew9 karma

Maybe an obvious question, but what's the juiciest find you know of? The thing that you really can't explain?

sshostak22 karma

I know this is disappointing ... but all the signals we find these days are checked out, and quickly discarded as terrestrial interference. In the old days of SETI, we'd record data ... and look at it later. That's when you would find things like the "Wow" signal -- which we couldn't check out very easily. But probably all those early "unexplained" signals were interference too.

UncleMatthew13 karma

You have simultaneously crushed by spirits with your response but raised them with its promptness, professionalism, and clarity. I am confused, but thank you. I think.

sshostak13 karma

Professional and clear, but now you're confused? Guess it wasn't either professional or clear!

SolomonGrumpy5 karma

Do you ever wonder if somehow upper management was deliberately obfuscating real alien communication (like introducing bugs into pattern recognition algorithms so that they are mislabeled "terrestrial interference?")

sshostak20 karma

Let me assure you, they have neither the incentive nor the technical ability to do this!

flyingvader9 karma

How long until Gary has his own comedy show?

sshostak18 karma

You'll have to talk to Gary about this!

flyingvader8 karma

Gary, please do an AMA!

sshostak24 karma

I'll pass your request on to him!

hhhnnnnnggggggg8 karma

So, when can we expect space colonies?

sshostak15 karma

In the 1970s, it was predicted that tens of millions of people would be living in orbiting space colonies by the 1990s. Didn't happen. I figure towards the end of this century.

Fuqwon8 karma

How often do you wake up hoping that it's finally the day you start to live out the plot of The Arrival?

sshostak16 karma

Not often! If you do that, you'll be destroyed by dashed hopes.

PurpleHaseman8 karma

What it is the best way an average joe can promote the SETI Institute.

sshostak22 karma

Tell your friends. Or maybe, if you're a skywriter, you could write the name of the organization in the skies above, say, New York!

[deleted]28 karma


sshostak26 karma

Can't imagine.

rgower7 karma

Do you ever lay awake at night wondering if the evolutionary history of Earth was necessary for intelligence? If the evolutionary history was necessary, then it seems highly unlikely that it exists elsewhere given the immense variation of paths life can take.

So the philosophy of SETI is rooted in the notion that intelligence is convergent, an idea that I find persuasive... but not absolutely convincing until we have a second data point! Does that ever keep you up at night?

Edit: BTW I'm a huge SETI fan, even made this video for you guys. Keep it up!

sshostak14 karma

Doesn't keep me up at night. Spicy food might. Yes, there are many paths evolution could take ... but hey, intelligence has survival value, so I figure it might occur in many places.

rgower3 karma

But one could argue that 2 hands and 2 feet (quadrupedalism), 10 fingers and toes, or even certain patterns of bird plumage have survival value. And yet of course we don't expect to see peacock feathers on alien worlds. In order for us to believe that intelligent life exists elsewhere in the cosmos, we have to believe that it has universal survival value and that the evolutionary road to get there is convergent.

Like I said, in all likelihood I think intelligent life exists elsewhere, but a small portion of me sees merit in arguments that say it's an Earthly anecdote like peacock feathers. And that small portion... keeps me up at night. Thanks for the answers and good luck :)

sshostak8 karma

The pessimistic point of view might be right, but we'll never settle this argument sitting around in bars, swigging beers. Need to do the experiment ... Right?

sshostak10 karma

Oh, and liked the video.

danoo7 karma

Love that you're doing this. Some random questions:

  • I remember reading somewhere about using the sun as a gravitational lense, putting a telescope way out near the sun and thus being to resolve objects with incredible resolution(like trees, vegetation on exoplanets). How doable is this currently besides the prohibitive distance?

  • Alpha Centauri, any updates on detected exoplanets there?

  • What is next after Kepler? It's a real shame there is not something like the TPF. We've got our priorities out of wack I say.

sshostak18 karma

Using the Sun as a gravitational lens works on paper ... but involves sending spacecraft to a distance 100 times farther than we've ever done. Maybe by the end of this century?

Agree about the TPF ... they say to write your congressman, but I'm not sure that's so efficacious these days.

freemarket276 karma

How many Earth like planets are close enough to our planet for their incidental radio wave transmissions to reach us? Stated the other way, how many "capable of supporting intelligent life" planets are close enough to Earth to be able to hear the radio wave broadcasts we are transmitting?

sshostak15 karma

We don't know this. But let's say that one in a thousand stars has an Earth-like planet (maybe not a bad guess ...) Then within 70 light-years (we've been broadcasting TV for 70 years) there are roughly 10 such planets.

MahaliAudran6 karma

What's a typical day at work like? Any plans to join Fraiser Cain and Dr. Pamela Gay during one of their weekly hangouts?

sshostak9 karma

I've been on Pamela Gay's podcast once. But do check out You might find it interesting.

nuclearblaster6 karma

What is your best guess about the 'wow' signal ?

sshostak15 karma

It wasn't found when a follow-up observation was made about one minute later. Best guess is that it was terrestrial interference.

astroman3005 karma

The ATA has started looking at Kepler planets for artificial radio signals. Given that the majority of Kepler planets are thousands of light years from Earth, how powerful would a radio transmission have to be to be detected by the ATA in its current 42 dish configuration?

sshostak14 karma

Good question, and I haven't actually worked the numbers carefully, but roughly this would require a transmitter power of 10 Megawatts or so if they have a transmitting antenna 1000 feet across (same as the Arecibo antenna in Puerto Rico)

astroman3007 karma

Wow. That's actually not as bad as I thought it might be. Wikipedia says Arecibo is capable of much more than that, so maybe you guys will find something after all. Good luck.

BTW, I read "Confessions of an Alien Hunter" and I loved it. Thanks.

sshostak17 karma

Thanks for the kind book review! I thank you. So does my Mom.

flyingvader2 karma

Not much of a point then?

sshostak20 karma

Wouldn't say that. We build megawatt transmitters. Why couldn't your average, technically inclined Klingon?

buzzti865 karma

What do you think of the Fermi Paradox?

sshostak16 karma

It's puzzling and paradoxical! But really, I wouldn't draw too many conclusions from a "local observation" about non-local truths.

buzzti865 karma

As a kid I enjoyed "playing" with the Drake equation. Recently I stumbled across Susan Blackmore's revised version of the equation. Here (starting at 13:30) she talks about it. She says it's more about replicators than "intelligence". Do you agree?

sshostak8 karma

I'm not sure I follow what she REALLY means, but hey ... Look, what's important is the number of places where something (replicator, life form, AI machine, or anything else you like) is able to build a radio transmitter. That's all.

Lewke5 karma

Any chance we can make the system distributed like galaxy quest, einstein@home and some of the other searching systems? Even if we have to start an open source project?

sshostak18 karma

We do have SETIlive, so check that out at The difficulty with all these programs is user support!

Lewke2 karma

i'll give it a go, anything to contribute :)

p.s. i'm a software/hardware dev, if theres anything else, let me know :D

sshostak5 karma

OK. Let me know if you find it worthwhile or otherwise.

Jerranto4 karma

Don't you think that the chances of an alien civilization transmitting radio waves is VERY low? I mean, what are the chances of an alien civilization have thrilled the same technological path as our civilization at all? Would they necessarily have to communicate via radio?

sshostak8 karma

On the basis of the physics we know, it's a very inexpensive way to send bits of info from one place to another.

Vitalic1234 karma

How can us ordinary citizen folk muster up interest in the public so that people are once again interested in exploring the cosmos?

sshostak13 karma

Good question, and I wish there were a straightforward, obvious-as-Bergerac's-nose answer. Better science education would help. But that's easy to say.


how big of a transmitter/receiver would we need in order to pick up a signal from andromeda galaxy?

sshostak12 karma

One that ws about 10,000 times larger in area than necessary to find the same signal from a planet around the nearest stars. So roughly twenty miles across!

radicalporotta3 karma

What is your daily routine like?

sshostak11 karma

These days ... mostly answering e-mail! Remember: the data analysis is done real time at the observatory. I don't sit here with headphones.

brit_in_LA3 karma

Some telescope observation that could only be caused by an ET? - It would have to be very BIG I guess...

Dyson sphere building or a supernova being used as a local BBQ or some such.....

If anybody could ever prove anything about String Theory could this be useful to SETI?

sshostak11 karma

Not sure how string theory could help, but of course I might have said the same thing about quantum mechanics a long time ago ... and it helps.

Like the idea of a supernova barbeque. Tasty, crispy critters.

freemarket272 karma

Did you expect that we would have heard something from an alien civilization by now?

sshostak12 karma

No. We've barely scratched the surface ... only looked carefully at about 1,000 star systems. Fortunately, the search is speeding up!

brit_in_LA2 karma

How far back do you think Proxmire in 78 and Congress in the 80/90s put back SETI?

Where would we be today if the money had been spent back then?


sshostak6 karma

No one can say. Proxmire only killed NASA SETI for a year, but the Bryan Senate amendment in 1993 killed it forever (or at least, until now). We'd have more and better experiments by now. And faster ones, too.

rainmatt2 karma

what novels do you read while the computers grind away at the data? and what would you say to 10 year old interested in science?

sshostak8 karma

I read the current month's selection of my book club.

To the 10 year old, I would answer questions and buy them an occasional book.

[deleted]2 karma


sshostak5 karma

Well, again, we do take a few student interns each summer ... mostly via NASA's REU program (check it out). It's a small number, alas.

Multiple universes seem to make sense from the point of view of physics. Not clear we can ever prove their existence, though.