# Sunsets are Quite Interesting

By Phil Plait | November 20, 2011 7:14 am

There’s a wonderful comedic quiz show in the UK called "QI" — for "Quite Interesting" — which is hosted by none other than Stephen Fry. The participants are comedians, and they’re asked questions ranging over just about every topic you can imagine. The BBC recently uploaded a clip about which alert BA Bloggee Brett Warburton informed me. In it, Fry shows the contestants a video of the Sun setting, and asks them to ring in when they think the Sun has completely set. Here’s the clip:

This is, in fact, correct! The Earth’s air bends the image of the Sun upward, so we can still see the Sun even though it is physically below the horizon. If we didn’t have air, daytime would be shorter. In fact, this effect works for sunrise as well, so we see the Sun rise before it’s physically cleared the horizon.

And Stephen was correct in the amount too; the light is bent upward by just about the same size as the Sun, so when the lower limb of the Sun just kisses the horizon it’s actually already set.

But it’s a bit more complicated, of course. The amount of bending changes as the Sun dips lower, because we’re seeing through more air the closer to the horizon we look. I’ve written about this before. In fact, I found a nice graph from NOAA showing the amount of bending:

The amount a ray of light is bent is shown on the vertical axis, and the distance from the horizon on the horizontal. The units are degrees, with 360° in a circle, of course, and the Sun’s size in the sky is about 0.5°. Reading off the graph, you can see that right on the horizon, a ray of light is bent upward by about a half degree. In fact, the light from the top of the Sun is bent less than the light from the bottom, so this effectively pushes the bottom of the Sun up toward the top, squishing it! You’ve probably seen countless pictures of the Sun looking squashed on the horizon (the Moon, too — I just posted about that yesterday, in fact!). Well, that’s why.

Now, what the comic was saying about the roads in New Zealand didn’t make much sense to me; the Sun gets low to the horizon everywhere at some point during the day (well, except maybe for the poles during their local summer, but they don’t have well-traveled roads anyway), so glaring reflections are always a problem.

I am endlessly fascinated by phenomena like this in the sky, and I’m pleased that "QI" was able to explain it to so many people. Even if one of the comics didn’t like it. But there you go: the Universe is under no obligation to make us like it. It does what it does, and you might as well enjoy it when you can.

Image credits: NOAA; NASA

Related posts:

CATEGORIZED UNDER: Astronomy, Cool stuff, Humor, illusion

1. “Its not there…” | Intelligent Life | November 21, 2011
2. Watch the lunar eclipse Saturday | 100planet.com | December 10, 2011
3. More than one horizon…. | Voyages Around My Camera | January 16, 2012
1. Why can’t we have a show like IQ with a host like Stephen Fry here in the US? Instead we get Motorcycling Midget Brides Wearing The Dress Cooking for Gold in Alaska, or some such nonsense…

2. critter42

Could what the comic talking about New Zealand be related to the ozone hole over the South Pole? IE, while not an actual increase in brightness, there would be an increase in UV radiation.

3. Bob

@critter42 no he’s just referring to the sun being close to the horizon due to NZ’s latitude.

4. jlbrewer

The stated reason QI isn’t much showing overseas (at least according to its page on tvtropes.org, dunno about more official sources) is that those images and videos they project on the big screens behind the panel cost a lot to license. So some of us have been making do with diligent Brits uploading the show right after it airs…

Anyway, for more science goodness, look up the show from a few weeks ago when Professor Brian Cox was a guest panelist. (Preferably the “QI XL” extended cut.

5. Gjeff

I’ve seen the show and I figure the New Zealand thing is just some nonsense made up for comedic effect. That’s typical Allan Davies for you. Or maybe New Zealanders are less likely to wear sunglasses while driving. I dunno. That’s typical me.

6. Chris P

@Larian LeQuella

I don’t know why you can’t have your own version, but the reason you don’t have reruns of our version on BBCAmerica is apparently because they have all sorts of problems clearing the images and videos they show on the backdrop screens for international viewing. which is a shame as it’s really an excellent show.

7. James

Waitaminit.
Doesn’t this imply that an observer could be as much as ½° of latitude south of the Arctic Circle but still see the midnight sun on a solstice day? After all, it’s image would be deflected above the local horizon.

8. Cindy

Larian,

Besides, when ever we Yanks try to copy a great British show, it always seems to fall flat. Examples: “Who’s line is it anyways”, “The Office”, “Top Gear”

Maybe it’s because with a British accent it sounds less sophomoric or just that they’re more likely to have fun making fun of themselves.

Though I would love an American version with Jim Carrey on it being asked about vaccines. I don’t know who would be a good host, though.

9. Saying the sun is not there is a bit harsh. The sun is there below the horizon reflecting it’s image above the horizon by a refraction of the atmosphere.

The real color of the sky isn’t blue, that’s an atmospheric illusion as well.
What’s the real color of the sun? Green http://bit.ly/uBPi7O

10. Sili

Well, technically, by the time we see the Sun touch the horizon is already eight minutes since the sun was there.

11. WJM

Motorcycling Midget Brides Wearing The Dress Cooking for Gold in Alaska

= = =

It’s actually Motorcycling Midget Polygamous Brides Wearing the Pawn-Shop Dress Cooking Cakes for Gold Coupons in Alaska With the Stars Plus Eight. And I love that show!

12. Chief

Nice that the science over there is still being taught, even though on a game show. Don’t think It would fly here in North America as it doesn’t have a wheel and annoying sound effects.

Thanks for the new unknown piece of trivia about sunsets/rises. I knew there are 8+ mins from the actual sun to the observed sun location in the sky but this adds to it.

13. Chris

I thought the issue with sunstrike in NZ was due to a combination of our low lying latitude and our winding twisty hilly little roads (Pratchett would say we have a lot of Terrain). Thus the low sun in the winter can be a day round threat of sun strike in some places.

14. We USians do have a show like that, except that it’s on radio: http://www.npr.org/programs/wait-wait-dont-tell-me

15. Other Paul

Hmm, @Sili. I don’t think you mean what you said, the way it comes across. Although the sun’s 8 light minutes away, our horizon isn’t.

And @LarianLeQuella – we get stuff like Jelly Chihuahuas in Sunglasses Tightrope Skiing over Cheddar Gorge too. There’s no escaping it. Nowhere is safe.

16. edwardv

How does this affect the definitions for the exact time of sunrise and sunset?

17. Tyrel

Don’t forget also that the slowness of the speed of light means that where we see the sun is actually where it was over 8 minutes prior. Then again, the sun isn’t really moving, it’s Earth that’s rotating, so maybe it is where we see it at… or not? Ugh. I’m all confused now.

18. Bette Noir

Thanks for the clip. I follow a lot of British comedians on Twitter, and I’m always frustrated when they say they’re going to be on QI, since I can’t get it here.

There’s a British parody site, analogous to The Onion, that gave, as their shocking news story one day, the canard that Stephen Fry is of merely average intelligence. I don’t think that fooled anyone.

19. Rich W

So, when you look up sunset times, are those ACTUAL sunset times, or are they APPARENT sunset times?

20. icewings

@Tyrel – The sun is moving, it’s orbiting the center of the Milky Way, which is also moving within the Universe.

Too many moving parts…My brain hurts!

21. @WJM and @OtherPaul, I think we need to start a contest on who can come up with the best encapsulating title of a show that shows what the Discovery Channel and The Learning Channel have devolved into. Although it would be hard to beat WMJ’s suggestion…

Also, sign up for the Discovery Influencer Panel. Maybe we can stop them from putting that sort of crap on the telly… https://www.influencerdiscovery.com/Portal/default.aspx

22. CameronSS

Thanks for the explanation, Phil! I saw that clip last week and found it hard to believe, but couldn’t imagine that Stephen Fry could possibly be wrong about something.

23. Jeffersonian

Here’s what I don’t get: After apparent sunrise, when do we see the sun its actual place? When it’s no longer angles through the atmosphere, the illusion is gone, correct? So at some point in its apparent ascension, does it suddenly jump one sun-width in place? (I realize it doesn’t but exactly how does it morph from its illusory position to its actual one?)

24. If sun strike is more of a problem in NZ than in many other countries, it’s probably down to the wonderfully clean air in this part of the world causing less atmospheric scattering of sunlight, for much the same reason sun strike can also be a problem when driving on the Moon.

25. Peter Ellis

James@7: Actually, the effect is amplified in Arctic regions due to the layering effect of different temperature air at different heights. The Sun can “rise” as much as 5 degrees on some days, meaning it appears days ahead of schedule at the Pole.

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

26. @#1 Larian Laquelle: Why can’t we have a show like IQ with a host like Stephen Fry here in the US? Instead we get Motorcycling Midget Brides Wearing The Dress Cooking for Gold in Alaska, or some such nonsense…

Bahaha, that’s pretty much exactly what I came here specifically to say!
Why can’t we have nice things?

Although, sadly, some of the shows you alluded to are some of the least brain-destroying things on American TV (for instance, that show with the amateurs trying to mine gold in Alaska). MOST of our TV seems more along the lines of “Steroid-pumped/silicone-injected orange apes boning and/or screaming at each other while stuffed suits call each other commie pinko terrorists in the background while spoiled rich girls make catty remarks about each other and cry.”

27. @#8 Cindy Besides, when ever we Yanks try to copy a great British show, it always seems to fall flat. Examples: “Who’s line is it anyways”, “The Office”, “Top Gear”
Maybe it’s because with a British accent it sounds less sophomoric or just that they’re more likely to have fun making fun of themselves.
Though I would love an American version with Jim Carrey on it being asked about vaccines. I don’t know who would be a good host, though.

I thought Top Gear was pretty cool, but then I saw the original British version. Then I had a sad.
I think you’re right, there’s something about a British accent – you can get away with more, and the dry humor sounds, well, more dry and more humorous 😛

The NZ sun thing, I think he meant that for some periods of the year, the sun remains low on the horizon all day long, so the sun strike issue doesn’t just apply towards either end of the day. Whether that’s true or not, I can’t comment.

29. Thomas Siefert

Two facts about New Zealand: There’s no snakes (not even in the zoos) and nobody wears sunglasses, except expat Aussies.

30. Robert

@Jeffersen: If you look at the graph, you’ll see that the diffraction angle slowly changes until the sun is directly overhead. So the angle just changes slowly until (solar) noon, and then increases slowly until sunset. As the graph also shows, most of that change is in the first hour.

And, as to why such shows don’t work when made in USA: There seems to be a belief there that “If you don’t take yourself seriously, no one else will.” It is something that annoys the rest of the world endlessly.

31. Kristof

What about the fact that sunlight takes 8 minutes to get here?
By the time you see the sun dipping below the horizon it’s already 8 minutes under right?

32. AJ

As a New Zealander (now living over seas) I think I know what Alan Davies was referring to. More then likely he spent some time in Auckland, the (by far) largest city in NZ. One of the largest (if not the largest) and busiest roads in the creatively titled “The North Western Motorway”.
I used to drive it every day on my way home from University.

Many tourists drive that motorway out to Waitakere and beyond to some of the most spectacular beaches in the world.

Unfortunately because of how the motorway is designed at some specific times of the year (usually summer) the direction you are driving is head first straight at the setting sun. Add a little rain before hand and you have a reflective road and BAM! can’t see a thing.
I’ve had days where I had to drop from 100kph (62 mph) down to a crawl of 20kph (13 mph) or slower and I simply could not see more than a few feet in front of my car, it was worse than some of the white out conditions I got when driving in Colorado.

And it can come without warning too, go around a corner and suddenly you can only pray to the great pasta in the sky to lead you to safety.

33. Mike Saunders

@30.

Yeah the sun in the eyes thing at extreme latitudes where it seems like the sun just rolls along the horizon is only challenged by when sailing on a super calm day as the sun sets.

Also the New Zealand thing is compounded by the types of rain they have, often it seems like its rains then lets up and is completely sunny outside.

34. sue-phi

this is interesting.
i am curious though, does elevation have any effect on how sunrise and sunset are perceived?
I would think that at higher elevations (depending on the surrounding landscape, of course) one would witness a slightly longer day. just wondering….

35. Freelance Minon

I have not seen enough of this show to know how similar it is, but it almost sounds like Wait, Wait Don’t Tell me on NPR which may be coming to some television network soon. Whether it does or not you can check out the podcast on iTunes.

36. Steve D

We had a transit of Mercury a few years back that might – just might – have been visible from not too far away from my home at sunrise. Was it worth traveling? I discovered that nobody predicts sunrise to the second, even though events like eclipses are predicted that precisely. The reason is atmospheric refraction, which is so variable that it can change the time of apparent sunrise or sunset by many seconds.

Then I had to be on the road the day of the transit, so I never saw it anyway.

37. Phil, can you tell us once and for all how many moons the Earth has? QI says we have 2 in this clip http://www.youtube.com/watch?v=D1zuAQAhhMI
But then a year later, they say there had been 3 more discovered! http://www.youtube.com/watch?v=D1zuAQAhhMI
Would be very interested to hear your thoughts.

38. samm

New Zealander a little bemused by this discussion….:)

Not sure what Davies is referring to TBH, since relatively speaking the UK is at a higher latitude than NZ, and thus potentially subject to more low lying sun than we are here. Methinks he is making it up/misinformed. At no time during the year does the sun remain low or near the horizon all day long in NZ. You get longer/shorter periods of daylight depending on how north/south you are, but horizon circling arctic circle style no.

I wouldn’t think sunstrike is any more or less of a problem here than any other particular place.

@ #31
Our climate is pretty much oceanic, hence subject to often frequent and dramatic changes over short periods of time.

@ #28 I wear sunglasses all the time (occasionally at night even. Handy for keeping track of visions in my eyes etc).

39. Roy Mongiovi

Hmmm… I’m not sure I can agree with this. When I look up “sunset” in the dictionary I see “The event or time of the daily disappearance of the sun below the western horizon”. So the fact that the atmosphere refracts light is already built in to the definition. Sunset is when the apparent position of the sun disappears below the horizon.

40. New Zealand isn’t at particularly extreme latitudes – it stretches from 29 to 53 degrees south, so it is neither as close to the equator as Miami nor as close to the pole as Edinburgh. Auckland, the largest city, is at roughly the same latitude as Fresno, California (except for being in the opposite hemisphere).

41. john

The most amusing part of the clip was the completely puzzled expressions on the faces of the panel.

Try watching it without sound, as I did.

42. Yuri

@Roy: I’m with you on this one…

This is a nice thing to know about, and I like the fact that science is being looked at on TV through day-to-day experiences. However, this is blatant equivocation on the definition of the word sunset, between “time at which the sun is no longer visible due to occlusion by [physical material on] the horizon” on one hand, and “time at which a straight line drawn from the upper edge of the sun through the [theoretical] horizon passes above the observer”. I suspect the second definition is more useful to astronomers, but this is an example of the kind of error Phil explored in his earlier post http://blogs.discovermagazine.com/badastronomy/2011/10/19/scientists-are-from-mars-the-public-is-from-earth/ , albiet a relatively inconsequential one.

Actually, you can show all kinds of interesting and surprising things by equivocating on the common definitions of words e.g.
Q: I pour all the water out of a cup, when is it empty?
A: It isn’t, there’s still quite a lot of air in there…

This comes down to a question of who ‘owns’ the word – just because I’ve come up with a more technically convenient definition for a word for an event in my field of study, does that make your old definition, understood and comprehended by the rest of the world, wrong all of a sudden? I’d say no, and one should be particularly clear about where you’re using the alternate definition, especially in contexts where older definitions are more useful and meaningful (as here). It’s all in good fun here, of course, but one needs to be wary of this kind of thing when there’s more at stake.

43. Chew

The definition of sunset has already been commented on here and by all known definitions of sunset QI was wrong. Fry was referring to the “celestial horizon” but he didn’t know it. To also call it a mirage is not accurate.

Temperature and pressure affect the refraction a small amount and elevation depresses the visible horizon; a higher elevation causing a delay in the time of sunset.

44. Yuri

Indeed. Stephen Fry was actually far closer in his terminology than Phil Plait on this one – tut tut…

45. Monkey

So simple I thought I would have known that…mysteries you never knew existed being uncovered each day. Science. Is. So. Cool.

46. Richie

From New Zealand.

I used to drive in/out of Auckland, NZ along a stretch known as the North Western Motorway. Get a bit of rain on that, then clear skies right afterwards and you can get really epic amounts of sunstrike. Thumbs up to Alan Davies for mentioning this unique hazard.

It can also get pretty bad along the Kapiti highway out of Wellington – the sun setting over the ocean isn’t as romantic when you’re driving right into it. It’s got a lot better since the road was resealed, but still…

47. abc

The universe doesn’t give a damn, it does what it wants.

Eww, look at that, the universe just made another star.

Is that a Coronal Mass Ejection? Gross! Eeeww, that black hole is so ugly. The universe doesn’t care. The universe doesn’t give a damn.

Look! It’s expanding! That’s SO disgusting!

48. captain swoop

One of the things about BBC progs compared to any other channel is that they don’t have to worry about keeping sponsors and advertisers happy. On ‘Top gear’ for example they can slag off a bad car without fear of the manufacturer pulling any advertising.

49. Nigel Depledge

Joseph G (27) said:

I thought Top Gear was pretty cool, but then I saw the original British version. Then I had a sad.

Well, I guess you could try emigrating, but you’ll find everything more expensive in Europe.

I think you’re right, there’s something about a British accent – you can get away with more, and the dry humor sounds, well, more dry and more humorous

Heh. For some strange reason this reminds me of the Top Gear episode in which messrs Hammond, Clarkson and May went to the southern US. They were challenged to buy a car in Florida for no more than \$1000 and drive it to New Orleans, with various challenges along the way.

One of their challenges was to drive through the little bit of Alabama that sticks southward from the rest of the state – simple enough, you might think, but they were given the opportunity to “decorate” one another’s cars beforehand. So, they ended up with slogans such as “Nascar sucks”, “Man-love rules” and “Hillary for president” on the cars they were driving through Alabama. They stopped for fuel, and ended up fleeing as they were pelted with rocks and threatened with shotguns (even the film crew had rocks thrown at them). The Alabamans featured quite obviously have no sense of humour and take themselves far too seriously.

Maybe the reason that many British shows don’t work when re-made for the US is because this attitude is not just restricted to Alabama?

50. Peter Davey

Regarding horizons, in his novel, “Game of Empire”, the late lamented Poul Anderson created a world which had no horizon, claiming that he had done so on the basis of established scientific principles, and that it would only take a comparatively minor change in the Earth’s size, and related criteria, to produce the same effect here.

Unfortunately, I don’t have the book with me, so I cannot quote the details of his claim, which was set out in an Appendix, running to several pages.

Perhaps we can appreciate horizons more, knowing that there was a possibility that we might not have had them.

51. JB of Brisbane

Not wanting to boast or anything, but Australia gets QI no questions asked, licence fees be damned.

52. Nigel Depledge

JLBrewer (4) said:

Anyway, for more science goodness, look up the show from a few weeks ago when Professor Brian Cox was a guest panelist. (Preferably the “QI XL” extended cut.

Oh, yes, that was an unforgettable episode.

Especially the bit about Ewoks . . .

53. PayasYouStargaze

Oh yes! The discussion of the nuances of tossing an ewok into a lake of fart. I laughed so hard at that.

54. Chris P

@48. captain swoop

“On ‘Top gear’ for example they can slag off a bad car without fear of the manufacturer pulling any advertising.”

… and even if they did, advertisers have far less say in the content of programs here in the UK than they do in the US.

55. Tibs

WOW. I was JUST contemplating this yesterday. I got a figure for an equatorial sunset that didn’t include airmass and it was so far from my experience that I just wanted someone ELSE to investigate the details.

Thanks Phil.

56. Jeffersonian (#23):

Here’s what I don’t get: After apparent sunrise, when do we see the sun its actual place?

Check the NOAA graph that BA posted above. You’ll see that the refraction goes to zero when the elevation is at 90 degrees. So, it’s always “wrong” unless it is directly overhead. (Well, it’s always “wrong” by 8 minutes, but that’s another story.) And, it doesn’t “jump”. Rather, the refraction slowly lessens as the Sun goes from sunrise to local noon, and then slowly increases towards sunset.

I suppose you could measure this effect by timing how long the Sun takes to travel its diameter near sunrise/sunset, and comparing that to local noon. Given the NOAA chart, I would expect the Sun to appear to move slower near the horizon than at noon.

57. gray lensman

QI is funny, intelligent (mostly) and informative but the humor is sophisticated in a seven-year-old English way, with lots of references to gay terms, body parts etc. If you watch with your kids, you might have to explain some embarrassing references and words. Adults shouldn’t have any problems , except maybe Aunt Tilly from the country. She probably won’t understand the accents anyway.

58. Calli Arcale

I don’t think the Sun’s position is ever wrong by 8 minutes, except due to atmospheric distortion. Light speed is a red herring.

Yes, you are seeing the Sun where it was eight minutes ago, but how much different is that than where it is now? If you think “well, just wait eight minutes and see where it is in the sky then”, you’ll be wrong. Most of the change in its apparent position is not due to the Sun’s motion but due to the Earth’s rotation. If you could see the Sun against the background of stars, you’d see that it doesn’t actually move very much at all in eight minutes. In fact, it takes a little over 365 days for it to make a complete circuit, so in a whole day it’s moving less than a degree. (If I’m thinking about this right. Monday morning mental math. Not ideal.) Light speed cannot realistically be a factor.

59. Jim A

Well…I actually put this down as one of those “trick questions,” that’s relies upon a misconception of the definition rather than anything actually clever. What is the definition of sunset? By whom and for what purpose? You can find several different definitions and none of the are “right” per se. Civil twilight might well be the definition that you need if the question is “what does ‘park closes at dark’ really mean?”

60. icemith

@50. Peter Davey Says:

“Regarding horizons, in his novel, “Game of Empire”, the late lamented Poul Anderson created a world which had no horizon, claiming that he had done so on the basis of established scientific principles, and that it would only take a comparatively minor change in the Earth’s size, and related criteria, to produce the same effect here…….”

I seem to remember a long time ago, maybe in the 50s or early 60s, there was an article in Popular Science (I think), relating to what we might see on some other planets, due to their different atmospheres, pressures and even the size of the planet.

I remember one example, and the staggering concept that there would, (could) be a view that would just go on, and on, and on to the zenith, not unlike a version of the effect a fisheye lens has on the perspective of any view at which we looked. I imagined it to be as if WE, the viewer, were literally at the bottom of the world, no matter where we actually were on that planet.

Obviously the Zenith would be at Infinity, and the detail would be lost of course. I also imagine it would be akin to looking from the bottom of a teardrop – from inside, and the light would just be reflected around. How light would enter initially, I have no idea, but it did cross my mind.

Sorry I can’t be of any more help with regard to the precise article, or who the author was.

Asimov? Sagan? Bradbury? Or the Editor of the magazine? No idea!

Ivan.

61. Jeeves

It should probably be noted that Alan Davies is the one permanent member on the panel, playing the role of token ignoramus. He is the low-brow “yin” to Stephen Fry’s professorial “yang”. It used to be that he finished last as a matter of course (although the scoring system is chaotic at best). These days he’s much more careful about blurting out the obvious, but wrong answer and he’s even finished first once or twice.

Still, any little-known fact stated by Alan Davies is very likely to be false.

By the way, the names of the panel members are (left to right) Phill Jupitus, Alan Davies, Ronni Ancona and Robert Webb.

62. Chris P

@Jim A

“Well…I actually put this down as one of those “trick questions,” that’s relies upon a misconception of the definition rather than anything actually clever.”

That’s what QI usually does; you don’t get points for being correct, just for being interesting (even if you go off on a tangent from the question asked). What’s more you lose points for giving the obvious, but wrong, answer, which is why the alarms went off when Phil Jupitus pressed the buzzer as the top of the sun disappeared below the horizon.
You can see the same thing in the clip Crystal (#37) linked to; Stephen Fry asks ‘How many moons does the Earth have?’ and Alan Davies answers ‘One’, setting off the bells and klaxons.

63. Twirrim

@icemith not sure what you’re specifically referring to, but 2 fascinating ideas I do recall on a related theme:

1) Ringworld. (Larry Niven?) A giant artificial planet, one big ring with a diameter roughly equal to Earth’s. Rotating at a speed sufficient to produce gravity. With the planet that shape there is no night, so giant squares are also in orbit.

2) Dyson sphere. Similar to Ringworld but a full sphere. Part of the idea is that it would be collecting the entire output from the sun, a massive source of energy to supply the needs of the world and it’s inhabitants.

64. Simon Green

@Sili, that’s a relativity fail. Everything is relative. For an observer on earth, the sun sets when we see it sets, and that is perfectly correct because it’s all relative to your status as observer.

An observer sitting off to the side (say in a parallel orbit with the earth, but 30 degrees along) would see something different, and an observer on the sun itself would see something different again. And they are ALL correct.

There is no independent objective ‘now’. That’s why it’s called the theory of relativity.

65. Chris S

I’ve read this several times now, and the up/down thing is really, really bugging me.

My description would be: on an airless earth, the path of the image of the sun would be over your head when the sun is below the horizon. However, the presence of the atmosphere causes atmospheric refraction. The result is that the atmosphere bends the image path so that it comes *down* to where you are. Even if I reverse the process, I imagine that my viewing path is bent *down* below the horizon.

Oddly enough – it feels overly haughty to refer to the “image is bent up” – because that’s only how *you* see it. I find that I get far less confused if I take myself out of the process, and just try to understand what is happening without treating myself as a preferred observer — because, as Copernicus instructs, there is no preferred point from which to observe.

66. @ 49 Nigel DePledge: …One of their [Top Gear] challenges was to drive through the little bit of Alabama that sticks southward from the rest of the state – simple enough, you might think, but they were given the opportunity to “decorate” one another’s cars beforehand. So, they ended up with slogans such as “Nascar sucks”, “Man-love rules” and “Hillary for president”

Bahahaha!!! I’ll have to try and dig that one up on Youtube.

Maybe the reason that many British shows don’t work when re-made for the US is because this attitude is not just restricted to Alabama?

I’d like to say it’s not, and in fact, there are plenty of places where such slogans might be par for the course. But yes, there are wide areas where people seem to have a much narrower view of what is socially acceptable. Only a tiny fraction of those people are going to result to brandishing rocks and guns, but still, they exist.
And they vote. Oh, do they ever.

67. @51 Peter Davey: Regarding horizons, in his novel, “Game of Empire”, the late lamented Poul Anderson created a world which had no horizon, claiming that he had done so on the basis of established scientific principles, and that it would only take a comparatively minor change in the Earth’s size, and related criteria, to produce the same effect here.

I’m scratching my head over this one. Was the world on the inside of a sphere?

68. Stan

Years ago, Sky & Telescope had an article regarding this phenomenon about the sun actually being below the horizon during apparent sunrise or sunset. The article describes one observer seeing the sun rise twice one morning! Though I have the magazines on DVD, I have yet to find that article. Searching the index using “double sunrise” or “double sunset” (just in case my memory is incorrect) does not work. Think it was sometime during the 1980’s.

69. Crux Australis

It annoys me without limit, when people, upon learning such fascinating and potentially world-view-changing information as this, respond with something akin to “That’s stupid; who cares?”, as Phil (OMFSM I wish this was my last name) Jupitus did. The same reaction occurs in that clip about Cruithne.

Oh, and as a driver in New Zealand, I’m not sure what Alan is on about, either. And I do wear sunglasses.

70. I love QI. Of course, being an American I have not watched every single episode of Qi at all. Nor have I watched them multiple times. I certainly have never done that.

71. Crux Australis, you really need to see more of QI to understand why Phil Jupitus is reacting that way. QI has a way of making the panelists doubt everything they think is right or sensible. Phil’s just been through one too many of those Klaxons.

72. Yuri

IIRC the “horizonless world” effect was a thought experiment in which the refraction effect mentioned in the above video/article is increased dramatically – instead of just seeing the sun higher in the sky than it is, the light would be sufficiently bent that you would see objects ‘behind’ the planet’s curvature as being above the horizontal plane, making a convex world appear concave from the surface – basically a planet-wide superior mirage. A sufficiently strong refractive effect would make light from objects on the other side of the planet curve all the way around and hit you from above, though in practice, the view would probably be lost in haze before that point – if all observable detail is lost in haze before the critical angle is reached, there would be no apparent horizon. Any incident light from the planet’s sun, moon(s), stars etc. would also be bent so as to come from directly above, for practical purposes.

The really interesting thing here would be the native’s reaction to extra-planetary visitors, given that their world is “obviously” the inside of a sphere and solid rock in all directions…

73. I’m still wondering, if the clip hadn’t run at high speed, how long it would have taken from when the horizon touches the lower part of the sun till it disappears. Or just how high above the horizon the sun was eight minutes before touching it.

After all, the trick in this trick question is making it about where the sun is in a geometric sense, and light speed should be taken into consideration. The contestants are of course wrong, but how wrong is Fry when he says “this is the time the sun has actually set” and the sun is just touching the horizon?

74. Buzz Parsec

Just want to point out that Alan Davies (the guy who mentioned the roads and drivers in New Zealand) was the star of the eminently skeptical Jonathan Creek

75. bob

Glad he got that one right. His explanation of how GPS worked was a bit embarrassing.

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