dg comments

please empty your brain below

Excellent - I'm loving this. Very well explained and endless fun, if that be the word, to be had with that sunset/altitude calculator. People never seem to notice sunsets climbing up skyscrapers - or maybe they just don't stand and stare at them like me. Likewise I don't know how many Londoners saw Mercury at about 6.30pm last week - if you happened to notice Venus shining brightly after sunset, Mercury was actually well above it. Question though - is there a map which takes into account the altitude of your apparent horizon, not just the altitude you are at? I've not made that clear, but standing on Richmond Hill watching the sunset, behind me in a direct line London is already in shade, partially because it is to the East, but part of that must be down to the height of the hill I'm standing on.

GJ | 18.03.18 - 8:07 a.m. | #

excellent write up. Your blog really is a cornucopia of wonders, you never know what you are going to get when you open it!
Thank you

richard | 18.03.18 - 8:15 a.m. | #

Is there a reason why the gain/loss of daylight in Spring/Autumn is longer than in the height of summer/depts of winter? From my reading of the tables and charts it looks like the rate of increase in daylight is not consistent throughout the 6 months of longer days.

dg writes: See previous posts.

Robert Butlin | 18.03.18 - 8:37 a.m. | #

The use of the word cornucopia by richard reminds me of another Bow pub now gone,The Horn of Plenty,alongside Mile End Station. It had a cornucopia bar back in the 1970's.
Regarding this post I started off thinking this was going to be boring and ended up aware of a sequence of which I had no idea existed. Bored to enthralled in one article. Thank you.

Dannyr | 18.03.18 - 8:57 a.m. | #

@Robert: It’s a smooth process so it has to slow down before it stops and goes in reverse.

Jimmy | 18.03.18 - 9:06 a.m. | #

I had noticed this phenomenon and idly wondered about it - and now I know! Thank you dg. I shall cut out and keep this post along with your previous fascinating astronomical explanations.

Sarah | Homepage | 18.03.18 - 9:27 a.m. | #

@Sarah,
astronomical: emphasizing that the previous explanations are very large indeed, of having to do with astronomy. I presume the latter.
What glory the English language!

scrumpy | 18.03.18 - 10:38 a.m. | #

I too shall save this post for future reference.
It warms my heart to learn the science behind what I observe. I just wish the weather would do the same!

Cornish Cockney | 18.03.18 - 10:47 a.m. | #

I became acutely aware of the massive differences when I moved into my new flat with south-facing wraparound balcony a few years ago. My summer sun rises above Canary Wharf, in winter it's almost Lewisham.

commonliner | 18.03.18 - 11:32 a.m. | #

All fascinating stuff.

In an idle moment I wondered what the flat earthers would make of it. Amazingly, the Flat Earth Society tries to give an explanation !

Somehow I can't get my head around their colourful diagram showing the sun whizzing around in expanding and contracting circles at varying heights, but always above the flat earth. If this were true, then the sun would always be visible to some extent.

Gerry | 18.03.18 - 11:40 a.m. | #

At 56N (the latitude of Edinburgh) the maxima and minima azimuths of sunrise and sunset are at 90 degrees to each other, so exactly NE, NE, SW, and SE.

I am told it is possible to see the sun set twice in Blackpool, first by watching from the beach, and then from the top of the Tower, where the sun will still be completely above the horizon. (It may depend how long you have to queue for the lift!)

timbo again | Homepage | 18.03.18 - 1:22 p.m. | #

I did know all that but could never have explained so clearly. But one point: are you defining sunrise (or sunset) as being the top visible limb of the sun or the centre? I presume you must mean the top.

Another rather insignificant factor is the state of the atmosphere: slightly non-standard refraction effects can be shift the apparent sun up or down compared to normal.

As for climbing Blackpool Tower and seeing two sunsets, I once saw three or four! I was an airline pilot and a stepped climb* out of Newcastle was memorable.

*Stepped climb is when Air Traffic Control cannot for whatever reason (usually other aircraft in the way!) permit steady climb and require several periods of level-off before resuming climb.

Jack

Jack Harrison | 18.03.18 - 3:11 p.m. | #

The shifting position of the sun across the sky through the year also causes problems for broadcasting.

For a few days in March and September, the sun rises through the part of the sky used for geostationary satellites. Satellite dishes are focussed at a very small patch of the sky, trying to pick up a relatively small radiated signal. This works fine until a much stronger emitter of radiation (ie the sun) moves behind the satellite - the receiver gets swamped by wideband radiation, and loses the intended signal in amongst all the noise.

It's entirely predictable (there's a calculator - so for contribution circuits, broadcasters can arrange to use a different satellite or downlink position (which would be affected at a different time), but for satellite viewers at home, there's no avoiding it.

martin | 18.03.18 - 3:14 p.m. | #

A great article, thanks. Having a west facing clear view from SW2, in winter the sun sets behind Tooting, and in summer north Kensington, just short off Grenfell tower. On certain days it's obscured by certain tall buildings along the horizon (sometimes it shines right through Empress State) and these have become markers in the procession of my year - one can easily imagine how Stonehenge tracked much more than the solstices. At any rate, longer days than nights from next week - hurrah!

NickW | 18.03.18 - 5:57 p.m. | #

If you go to Whitby near the summer solstice, you can see the somewhat disconcerting sight of the sun setting into the North Sea. The angle of the Cleveland coast is roughly WNW-ESE, so there is sea NW of you.

Gregg | 18.03.18 - 10:42 p.m. | #

Coincidentally I was watching a TV celebration of Ken Dodd last night, and this blog reminded me of one of his greatest lines - "My show is educational. As you leave, you'll be saying 'Well that taught me a lesson'".

MCG | 19.03.18 - 12:57 p.m. | #

I was saying to a colleague only the other day how much lighter the evenings are getting. Beats discussing the weather.

This astronomical dance causes Manhattanhenge - the phenomenon of the sun rising and setting in direct alignment with the east-west streets in New York (and elsewhere).

Thanks for mentioning Mercury, GJ. I am sad to have missed the best views last week - will try to catch it before its crescent disappears into the Sun.

Andrew | 19.03.18 - 2:18 p.m. | #

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