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Guest 112233
25th Aug 2009, 17:28
Ok - this one may have been done to death many years ago but here goes.

Imagine that you are at the latitude of the UK in mid/late summer and that you take off heading West say 10 minutes after sunset from ground level and climb fairly quickly in a passenger airliner at say 2500 ft per min - Will you see the sun rise and set again.

I know the speed of rotation of the earth's surface but given the geometry of climbing just after sunset does I think make it possible. The reason I ask is that from a childhood memory I think that I did see the sunset twice.

It was a Viscount in mid August leaving BHX for DUB, take off was at about 20.00 Hours hence the figures - obviously latitude matters, and time after sunset as well as aircraft performance - E G an F104 or Concorde just as the limb of the sun sinks below the horizon would be an extreame example.

Sorry it this is a repeat but the Maths and Geometry of the Idea make it a nice little conjecture.

Is my memory faulty ?

Thanks CAT III

Don Coyote
25th Aug 2009, 17:45
Saw it myself on departure from Heathrow not too long back.

FlyingScientist
25th Aug 2009, 18:21
Fly from London to Edinburgh.

Rainboe
25th Aug 2009, 18:24
No it's not a faulty memory! You would see the sun rise again, but you would only get partial disk rising in something like a Viscount (IMO!). However, set off in a jet for the West Coast, and as you go up toward Iceland and west across Greenland, the sun not only rises again a long way, but stays up there for 9 hours right in your eyes, then as you arrive at LAX, it drops below the horizon at last. Quite disconcerting to get used to.

Guest 112233
25th Aug 2009, 18:45
Ah great - Yes It was a Viscount - I simplified the Prob a bit. We went North West sort of; Staffa, WAL Lynas way - so there was a bit of help from the shape of the earth - And the orb was very low on the horizon. Big window syndrome again.

CAT III

Seat62K
26th Aug 2009, 08:28
Off topic, I know, but the following experience might be of interest:

Departed Heathrow at 1730, arrived Vancouver at 1715. This was only possible because the UK had changed to summer time before Canada, combined with a fast journey (8h45).

Pax Vobiscum
27th Aug 2009, 15:07
Alternatively, any evening departure east-bound trans-pacific flight will allow you to witness two sunsets on the same day - having set your watch back ~20 hours on crossing the date line. :ok:

Bushfiva
28th Aug 2009, 02:02
Do a full day's work in Tokyo on Thursday. Get the evening plane to Hawaii just after local sunset. Work on the plane. Land in Hawaii, it's Thursday morning again. Do a full day's work. Get one day's pay. :bored:

PV,
having set your watch back ~20 hours on crossing the date line

Actually, it's exactly 24 hours...:)

Pax Vobiscum
28th Aug 2009, 20:56
Well, if you want to be picky it's 23 hours, Bushfiva (if it's 19:59 on Tuesday just as you approach the date line, it will be 21:01 on Monday shortly after you cross it) - but I, for one, don't reset my watch every time I overfly a time zone change. :)

Tough luck about the two days' work for one day's pay, but hopefully you'll make it up on your next west-bound trans-Pacific flight. :ok: