Meet Joe. Joe is generally an average person with one special trait: He loves astronomy and star gazing.

However, Joe has a great paying job as a web developer. He earns 120 000 USD yearly and has a fully remote job, which has only two requirements:

  • Joe needs an internet connection
  • For legal purposes, Joe needs to work from the USA

Joe lives a moderate life and invests most of his earnings into astronomy equipment. Web developer by day, amateur astronomer by night.

Joe's astronomy hobby is his passion. He is able (and willing) to spend up to 70 000 USD yearly for equipment and he was equipping his observatory for past 5 years. (350 000 USD budget total for his equipment.)

Let's also assume that Joe started to hunt asteroids a year ago, so the past 70 000 USD can be spent directly for equipment related to asteroid hunting.

A rogue asteroid of the same magnitude as the one which killed the dinosaurs (10 - 15 km in diameter) is on a collision course with Earth. It will hit Earth 365 days from now.

  • Is Joe able to spot it?
  • Is it plausible that Joe will be the first one to spot it?
  • 4
    $\begingroup$ How much is Joe willing to spend on his hobby? It's a massive difference between having a hobby backyard telescope in the \$1,000 to \$5,000 range, and a large setup that might well cost hundreds of thousands of dollars. If you can give us some idea of Joe's budget, or even better what type of equipment he actually has available (good hobby telescope or small observatory; primarily astrophotography or direct visual observation; with or without az/el tracking; etc), that may help us give better answers. $\endgroup$
    – user
    Commented Aug 29, 2017 at 8:11
  • 33
    $\begingroup$ Moderate life, and 70k for a hobby? I need me one of those web developer jobs. $\endgroup$
    – Innovine
    Commented Aug 29, 2017 at 10:14
  • 13
    $\begingroup$ @Innovine If you can earn in Silicon Valley, but pay rent in Montana, you're rich. $\endgroup$
    – Agent_L
    Commented Aug 29, 2017 at 11:57
  • 4
    $\begingroup$ @Agent_L that 70k is more than my total annual income, before tax :( Seems an excessive hobby budget to me, but whatever.. Not that I live in the US either, but still, Joes hobby budget is still higher than the median wage in the US. $\endgroup$
    – Innovine
    Commented Aug 29, 2017 at 12:35
  • 4
    $\begingroup$ @Innovine So's his income, I guess, so it evens out... $\endgroup$
    – user
    Commented Aug 29, 2017 at 12:49

5 Answers 5


The sky is too big to let only professional astronomers look at it. Consider that professional telescopes have limited time windows for specific researches. And if you want to spot potential hazards for the planet you cannot look once in a while. At least, to watch over my house for theft I would not pay for a guard who looks at it just 1 hour every week.

NASA is actually distributing software to help amateurs spotting asteroids

In order to increase the frequency of asteroid detection, including of those bodies that could be potential threats to our planet, NASA has released a new software, developed in collaboration with Planetary Resources, Inc., capable of running on any standard PC. The software, which can be downloaded for free, will accept images from a telescope and run an algorithm on them to determine celestial bodies that are moving in a manner consistent with an asteroid. Amateur astronomers and asteroid hunters can also take images from their own telescopes and analyze them with the software.

Moreover there are already cases where an amateur found a newly discovered asteroids

last year Maley started enlisting amateur observers in Texas to observe the occultation of a 10th-magnitude star by 13th-magnitude Amalthea. And all that planning paid off, because the observing team has discovered that this asteroid probably has a small satellite.

So the answer to both your question is YES (if he also uses the equipment he has).

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – user
    Commented Sep 1, 2017 at 7:25

I upvoted Dutch and did not think anything else was needed; but in response to commentary I will add on.

  • Is Joe able to spot it?

This is an unqualified YES.

Amateurs spot new asteroids and comets all the time; it is just a matter of equipment that is affordable to many in the upper middle class, like Joe. Some people buy \$200,000 boats for their hobby, others could spend that on astronomy instead.

I have spent 40 years either earning in Joe's range or above it but working daily with people that earn in that range; and I know from personal contact it is plausible for some to spend lavishly on their hobbies. Perhaps \$70,000 a year would be an outlier, but not implausible. Make Joe a little older (warranting the higher remote salary) and he could easily have half a million dollars worth of equipment. He is technically minded, he can understand and compute the trajectories, speeds, etc. As a computer developer he can probably program accurate simulations to find places to look, or discover anomalies. Joe can be, effectively, the same as a professional astronomer with professional equipment matching the typical university observatory setup.

  • Is it plausible that Joe will be the first one to spot it?

Another unqualified YES that apparently needs explanation. It is plausible that some amateur will find it. Why Joe out of the hundreds or thousands it might have been?

That is a question that does not have to be answered! In fiction, the author focuses on the characters that eventually get lucky or do something extraordinary; that is the nature of story telling. We generally do not take some random person and tell about their ordinary life where nothing of any real consequence happens.

Consider Stephen King's (SK) "The Stand". He focuses very early on Stu Redman, a reasonably intelligent guy hanging out at a gas station with his buddies in a small town in Texas. The Superflu, a bio-engineered disease that none of the characters have heard of, is about to escape and kill 99.999% of all humanity.

Why would SK focus on Stu? Because this gas station is about to be crashed into by patient zero, a soldier infected with the Superflu, and Arnette is about to be ground zero for the spread of this infection, and Stu is about to be the first person in the world to be proven immune; due to a 1 in 100,000 chance mutation in his DNA that has had no effect upon him so far.

What are the odds THIS gas station, out of millions in the world, is where patient zero dies at the wheel and crashes? What are the odds of THIS small town being where it happens, out of tens of thousands of such towns? What are the odds this guy is immune (1 in 100,000) and happens to be AT this gas station and hanging out with his buddies?

The odds of such a coincidence are beyond those of winning hundreds of millions of dollars in a lottery. But it is the fiction writer's prerogative and duty to focus precisely such situations because that is where the story is.

In SK case, each component is plausible, so suspension of disbelief is sustained. Somebody has to be the first survivor, so SK begins his story from the POV of that person, no matter how long the odds of any individual being that person. In Stu Redman's case, out of 7 billion people on Earth, the odds of him being both immune and the first are one in 7 billion.

I could say the same about Harry Potter: The odds of being the one out of billions is one out of billions. Or being the best secret agent, the President of the USA when extraterrestials visit or an asteroid strikes, or being invited to Jurassic Park, or being the best martial artist in the world, and so on.

Fiction writers are expected to focus on the one unique person that is going to be "The One" and tell their story.

So because it is plausible an amateur will be the first to spot it, of course it is possible Joe is "The One". Because this is fiction and the author would not focus their tale on anybody else but "The One." That is expected by the audience (readers, viewers, listeners) and does not break the suspension of disbelief in the slightest. On the first pages of a novel (or a chapter or other story cut that introduces a new character) we fully expect the focus to be on characters that will matter to the story line. The earlier in the book or movie these characters are introduced, the more important to the tale they should be (e.g. it breaks suspension of disbelief if the plot resolution comes from a character first introduced near the end of the tale; so much so we consider this to be poor storytelling [pejoratively called a deus ex machina]).

Somebody has to discover it and that might as well be amateur Joe; the OP has given plenty of reasons (perhaps too many) to tilt the odds in Joe's favor. Authors are nearly always telling the tales of people experiencing an extraordinarily unlikely string of individually entirely plausible and possible events or circumstances. Because that's where the story is!

  • 5
    $\begingroup$ Terry Lovejoy is an Australian amateur astronomer who discovered six comets. $\endgroup$
    – AlexP
    Commented Aug 29, 2017 at 12:12
  • 2
    $\begingroup$ This is a really long, off-topic rant, not an answer. The second OP question focusses on how plausable it is that this specific Joe is the one who discovers the asteroid. nothing in the above text quantifies joes plausability. You were much closer when you said he might look for 5 hours a night. That would make it more plausable to be joe than someone looking 1hr a night. 5 times more. Now if joe had two telescopes, he could cover twice the search area, doubling his chances again. Sadly, you went off on a tangent about The Stand and Harry Potter, so downvoted for just being irrelevant ranting $\endgroup$
    – Innovine
    Commented Aug 29, 2017 at 12:39
  • 21
    $\begingroup$ @Innovine I don't care about downvotes, and you are wrong. This is a site about people creating fiction, and how fiction works is entirely the point. Of course it is plausibly this Joe because he has at least as good a chance as any other amateur, and as a matter of craft an author always focuses on the one character that is going to be relevant. The others are specific examples to prove that point, not irrelevant in the least. The odds of anybody being the first to find it are obviously minuscule, but if found, then obviously somebody was first. $\endgroup$
    – Amadeus
    Commented Aug 29, 2017 at 14:35
  • 8
    $\begingroup$ This question asks about plausibility not probability. What are the mathematical odds of Joe being the one who [insert unlikely event]? Who cares? That's a math question, plausibility has nothing to do with math, it's about human belief. $\endgroup$
    – barbecue
    Commented Aug 29, 2017 at 19:22
  • 2
    $\begingroup$ @barbecue: It's not even unlikely. The premise is that an asteroid has been discovered. The only two options are that its discoverer is a professional or an amateur. $\endgroup$
    – MSalters
    Commented Aug 30, 2017 at 13:10

Asteroids are really hard to spot at all, you need repeated high res images of the same piece of sky and a lot of luck, ones coming straight at you can actually be completely impossible to spot depending on the angles etc... If Joe is using good equipment, at the top end of amateur status, and the right techniques, as in he's actually looking for space rocks and he gets lucky there's no reason he can't spot it as long as there's some relative motion that he can spot.

Edit: Hadn't addressed part two sorry. The sky is huge part of Joe's "luck" is in picking the right piece of sky; odds are his piece of sky isn't being watched by anyone else so if he spots it it's not only plausible but actually likely that he's first.

  • 1
    $\begingroup$ i like how this answer points out something else about Joe's character that might help - not only is he an avid astronomer, but he should be a "maverick" too - he's looking at parts of the sky no one else is looking for asteroids, because he has some radical theories that few others share which cause him to look there. That's why he spots the asteroid first - perhaps he's looking perpindicular to the ecliptic, for example. $\endgroup$
    – Adam Wykes
    Commented Aug 29, 2017 at 16:41
  • $\begingroup$ He doesn't have to be a Maverick to be looking elsewhere from the ecliptic plane. NEAs can appear ,anywhere against the sky from Earth, especially if they have extremely small orbital inclinations. $\endgroup$
    – notovny
    Commented Aug 30, 2017 at 16:41

Yes, Joe could certainly have a chance to spot it. He's got the money to set up one or more automated telescope systems that can sit there all night imaging different parts of the sky, and then automatically chewing through the images to look for anything not matching the expected results and flag them for human attention.

There's at least one real world amateur astronomer that has done this and discovered several comets like this - I remember reading about it since he let his kids find some of the later ones. Don't have a reference, unfortunately.

The big multiplier is being able to automate things so you don't have to be up driving things all night p or doing the initial checks. Given a suitable budget, you can also set up one or more extra remotely operated sites in different countries so you can still image while it's daylight at home.

Once you've got the flagged images, it should be fairly easy to blink between the reference and "interesting" images to weed out a lot of planes and similar false positives - especially if things are set up to take more pictures of the same area later for flagged images.


Amateur discovery of comets, asteroids, minor planets, etc., has already happened many times. First discovery of Earth-intersecting planet-killers, not so much.

There is a list of minor planet discoverers at the International Astronomical Union Minor Planet Center, and a similar list at Wikipedia. Looking down the list in descending order of number of discoveries, I see the 'amateurs'

And so on. What's an amateur, anyway?

Looking at this from a different angle, assuming a constant, non-accelerating, average velocity of 25km/sec (here), the dino-killer would travel 788,400,000km in 365 days.

The distance of the Earth to the Sun, or 1AU, is 149,597,871km.

So the dino-killer would be 5.27AU from Earth when Joe spots it, or about the distance of Jupiter from the Sun.

So maybe another way to think of this is: what is the probability that an 'amateur' can discover a 10km asteroid at about the distance of Jupiter, taking enough observations (over what period of time) to accurately calculate a trajectory that will intersect Earth?


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .