Science, Experiment, and the failure of Reality.

[TANGODANCER]

If it's not pissing it down tonight, and the skies are cloud free, stand in your kitchen door at 10 o'clock tonight, and turn 35 degrees to your left. If a tree isn't blocking your view, down close to the horizon will be the brightest dot in the dusk sky.
That's Jupiter.

Thanks. A, it is pxxsing down, B my house sits at the foot of what used to be the old railway embankment, and C, I can't see the wood for trees, literally. I'll keep looking though.

[Lost Leopard Spot]

If it's not pissing it down tonight, and the skies are cloud free, stand in your kitchen door at 10 o'clock tonight, and turn 35 degrees to your left. If a tree isn't blocking your view, down close to the horizon will be the brightest dot in the dusk sky.
That's Jupiter.

Thanks. A, it is pxxsing down, B my house sits at the foot of what used to be the old railway embankment, and C, I can't see the wood for trees, literally. I'll keep looking though.

you'll not be seeing Jupiter tonight then.

[Dujon]

Spotty, is this the unit of which you speak?

http://www.flybird.co.uk/helios_evostar_458_2.htm

It looks like a decent sort of kit. If the objective lens (150mm) is tucked in the forward end of that tube, then it's a formidable piece of equipment, including a decent mount. Is chromatic aberration a problem? Most refractors I've used (not necessarily owned) exhibited this somewhat disconcerting trait, even those with claimed anti-CA lens coatings. I'd appreciate your comment.

By the way, I sold the Newt and its mount and accessories a few years ago. 9mm, 15mm and 25mm eyepieces plus a 2xBarlow and visual collimator , not laser (which I had, but was totally useless - it was so sloppy in the eyepiece holder that I could wobble it to an extraordinary degree). I must have valued the collection well below market price as I was inundated with offers to purchase when I advertised it as 'for sale'.

[Dujon]

To you, TANGO, and your star map question.

The majority of star maps that include your part of the northern hemisphere and are centred roughly on your location put you at the centre of the map and are marked outside the circle, which indicates your horizon (excluding obstructions) with the four cardinal points (north, south, east and west).

Now, with the map laid out before you on your table or lap, move the map so that the direction you wish to view is at the top of the map. Beware here, as magnetic (compass) readings are not true pole readings. I don't know your offset (see later), mine is about 11º eastwards from north. In your case I think the deviation is only about 0.5º west (about the width of the Moon) so it shouldn't be a problem for visual observations.

Once you have organised that, then the area at which you are looking on the map should be, when you raise your eyes to the sky, the same as the map. Please note that I am not disagreeing with Spotty's explanation, merely attempting to simplify it.

[Lost Leopard Spot]

Spotty, is this the unit of which you speak?

http://www.flybird.co.uk/helios_evostar_458_2.htm

It looks like a decent sort of kit. If the objective lens (150mm) is tucked in the forward end of that tube, then it's a formidable piece of equipment, including a decent mount. Is chromatic aberration a problem? Most refractors I've used (not necessarily owned) exhibited this somewhat disconcerting trait, even those with claimed anti-CA lens coatings. I'd appreciate your comment.

By the way, I sold the Newt and its mount and accessories a few years ago. 9mm, 15mm and 25mm eyepieces plus a 2xBarlow and visual collimator , not laser (which I had, but was totally useless - it was so sloppy in the eyepiece holder that I could wobble it to an extraordinary degree). I must have valued the collection well below market price as I was inundated with offers to purchase when I advertised it as 'for sale'.

Similar to that, but not the same. Mine is an older version of that particular kit. Main difference is D=125mm and F=1000mm. The lenses in the older kit are however superior - the one in your link has coated lenses made in China, very nice lenses, but mine has coated lenses made in Germany, outstanding lenses.
The mounts are identical are are very sturdy and smooth.
As for Chromatic Aberration, I don't think you can get any refractor instrument completely free of it, but mine is virtually free of CA. The only time I notice it at all, and only on the very edges of the image, is when I'm moon viewing at full moon, and that is fairly easy to resolve by putting the edge mask over the front end so that only the centre of the lens is gathering light, which cuts out the CA completely. But I usually don't bother because by the time I've lugged the bloody thing out onto the patio and set everything up, I've either forgotten where I stored the edge mask or can't find it in the dark

[Enoch]

I looked up at four this morning and there wasn't a single point of light visible in the sky, not a single one. Was quite bright though, couldn't say if it was a fullish moon behind cloud, or the sun coming up.

[TANGODANCER]

I've got a headache just reading about it Dujon. I think I'd better ask a policeman..or something.

Anyway, it's dark and peeing down again today....

[Lost Leopard Spot]

I looked up at four this morning and there wasn't a single point of light visible in the sky, not a single one. Was quite bright though, couldn't say if it was a fullish moon behind cloud, or the sun coming up.

Twas a waning crescent moon this morning, and would have been sitting just below the horizon at 4am about to rise. Sunrise was ~5:15am (in your neck o'the woods). Therefore I'd say the illumination was a combination of both sun and moon lighting up the upper atmosphere.

[TANGODANCER]

I looked up at four this morning and there wasn't a single point of light visible in the sky, not a single one. Was quite bright though, couldn't say if it was a fullish moon behind cloud, or the sun coming up.

Twas a waning crescent moon this morning, and would have been sitting just below the horizon at 4am about to rise. Sunrise was ~5:15am (in your neck o'the woods). Therefore I'd say the illumination was a combination of both sun and moon lighting up the upper atmosphere.

Just how much can "The sun rises in the east and sets in the west be relied upon as actual ease/west compass points, Spots?

[Lost Leopard Spot]

I looked up at four this morning and there wasn't a single point of light visible in the sky, not a single one. Was quite bright though, couldn't say if it was a fullish moon behind cloud, or the sun coming up.

Twas a waning crescent moon this morning, and would have been sitting just below the horizon at 4am about to rise. Sunrise was ~5:15am (in your neck o'the woods). Therefore I'd say the illumination was a combination of both sun and moon lighting up the upper atmosphere.

Just how much can "The sun rises in the east and sets in the west be relied upon as actual ease/west compass points, Spots?

Like a stopped clock that is correct twice a day, the sun rises in the East and sets in the West twice a year.
Think of a sine wave with the first peak being winter in the northern hemisphere and the first trough being summer in the northern hemisphere, that is the path the sunrise follows. A transverse line through the sine wave describes the east-west axis. When the sine wave crosses the mid transverse line that is when the sun rises exactly in the east. These are very near the equinoxes. The sunrise in the East and sunset in the West are usually staggered by a day or three, as sunrise and sunset follow slightly different sine wave patterns.

You've got to remember, also, that a day is only extremely rarely exactly twenty four hours long. The Earth spinning around in one complete rotation is longer than when the Earth spins to face the sun again. The siderial day is 23 hours 56 minutes and 4 seconds long.
Where the siderial day meets the equinoctic has a relevance as to when the sun rises in the east.

[TANGODANCER]

Thanks. All of which serves to remind me of my father's simple view of things: "The more you know, the more you know you don't know" He was but a humble labourer with common sense.

[Lost Leopard Spot]

Thanks. All of which serves to remind me of my father's simple view of things: "The more you know, the more you know you don't know" He was but a humble labourer with common sense.

Thing is, the sun never rises in the West, nor does it ever set in the East. So for all practical purposes you don't ever need to know Exactly where East is, do you? So your father was right.

[TANGODANCER]

Thanks. All of which serves to remind me of my father's simple view of things: "The more you know, the more you know you don't know" He was but a humble labourer with common sense.

Thing is, the sun never rises in the West, nor does it ever set in the East. So for all practical purposes you don't ever need to know Exactly where East is, do you? So your father was right.

A lot of this stems from a little experiment I did. I have a flagged patio at the rear of the house and I set a stick in one corner of a central flag in it (in the old boy-scout adage of finding east-west by the shadow and pebble method.) I suppose for what I need, that's good enough as I can mark the compass points on the flag itself (all just curiosity really) I'd paint them on but my wife is more Crystabel than Chistopher where exploring is concerned. She does know Morrisons is "almost" due north of our front gate and Asda Bolton a bit north east as the crow flies (does she xxxx) .

[Lost Leopard Spot]

Thanks. All of which serves to remind me of my father's simple view of things: "The more you know, the more you know you don't know" He was but a humble labourer with common sense.

Thing is, the sun never rises in the West, nor does it ever set in the East. So for all practical purposes you don't ever need to know Exactly where East is, do you? So your father was right.

A lot of this stems from a little experiment I did. I have a flagged patio at the rear of the house and I set a stick in one corner of a central flag in it (in the old boy-scout adage of finding east-west by the shadow and pebble method.) I suppose for what I need, that's good enough as I can mark the compass points on the flag itself (all just curiosity really) I'd paint them on but my wife is more Crystabel than Chistopher where exploring is concerned. She does know Morrisons is "almost" due north of our front gate and Asda Bolton a bit north east as the crow flies (does she xxxx) .

Ahhhh. The old sundial.
Three things.
We change over between GMT and BST twice a year, which kicks a bloody big hole in't'owd sundial timekeeping.
Second: as summer lengthens, shadows shorten - it's no good having a pebble stuck where winter noon is when your summer shadow is feet off it.
Thirdly. We lie north of the equator, so your east-west sundial line will follow a curve, not a straight line.

Other than that, I reckon you'll be fine.

[TANGODANCER]

Ahhhh. The old sundial.
Three things.
We change over between GMT and BST twice a year, which kicks a bloody big hole in't'owd sundial timekeeping.
Second: as summer lengthens, shadows shorten - it's no good having a pebble stuck where winter noon is when your summer shadow is feet off it.
Thirdly. We lie north of the equator, so your east-west sundial line will follow a curve, not a straight line. Other than that, I reckon you'll be fine. :

Ah, but the pebbles (two actually) are to point the west and east line over a period of time are they not? Is that not a reliable fact? Surely the length is immaterial summer or winter as long as it's discernible?

[Lost Leopard Spot]

Ahhhh. The old sundial.
Three things.
We change over between GMT and BST twice a year, which kicks a bloody big hole in't'owd sundial timekeeping.
Second: as summer lengthens, shadows shorten - it's no good having a pebble stuck where winter noon is when your summer shadow is feet off it.
Thirdly. We lie north of the equator, so your east-west sundial line will follow a curve, not a straight line. Other than that, I reckon you'll be fine. :

Ah, but the pebbles (two actually) are to point the west and east line over a period of time are they not? Is that not a reliable fact? Surely the length is immaterial summer or winter as long as it's discernible?

Your north and south pebbles (call them Norman and Scotty) will be in straight line.
But 'Enery and Wesley pebbles won't be. Each and every day they will move. Starting in winter they will be up near Norman's latitude and far away, but as summer comes they'll move nearer Mr. Stick and descend (like teenage bollox) towards Scotty!

[TANGODANCER]

Ahhhh. The old sundial.
Three things.
We change over between GMT and BST twice a year, which kicks a bloody big hole in't'owd sundial timekeeping.
Second: as summer lengthens, shadows shorten - it's no good having a pebble stuck where winter noon is when your summer shadow is feet off it.
Thirdly. We lie north of the equator, so your east-west sundial line will follow a curve, not a straight line. Other than that, I reckon you'll be fine. :

Ah, but the pebbles (two actually) are to point the west and east line over a period of time are they not? Is that not a reliable fact? Surely the length is immaterial summer or winter as long as it's discernible?

Your north and south pebbles (call them Norman and Scotty) will be in straight line.
But 'Enery and Wesley pebbles won't be. Each and every day they will move. Starting in winter they will be up near Norman's latitude and far away, but as summer comes they'll move nearer Mr. Stick and descend (like teenage bollox) towards Scotty!

Ah, right. I'm off to buy another pocket compass...

[malcd1]

Ahhhh. The old sundial.
Three things.
We change over between GMT and BST twice a year, which kicks a bloody big hole in't'owd sundial timekeeping.
Second: as summer lengthens, shadows shorten - it's no good having a pebble stuck where winter noon is when your summer shadow is feet off it.
Thirdly. We lie north of the equator, so your east-west sundial line will follow a curve, not a straight line. Other than that, I reckon you'll be fine. :

Ah, but the pebbles (two actually) are to point the west and east line over a period of time are they not? Is that not a reliable fact? Surely the length is immaterial summer or winter as long as it's discernible?

Your north and south pebbles (call them Norman and Scotty) will be in straight line.
But 'Enery and Wesley pebbles won't be. Each and every day they will move. Starting in winter they will be up near Norman's latitude and far away, but as summer comes they'll move nearer Mr. Stick and descend (like teenage bollox) towards Scotty!

Ah, right. I'm off to buy another pocket compass...

Magnetic north is changing faster than ever before so although still 'fairly' accurate it is moving by 30 miles per year. Experts are predicting it may be about to flip to the south pole soon. Apparently this happens around every 400,000 years but it is 780,000 years since it last flipped. According to this article, it takes around 10,000 years so you should get some use from that compass for a few years yet.

https://www.mnn.com/earth-matters/clima ... nal-pole-r

[Lost Leopard Spot]

Ahhhh. The old sundial.
Three things.
We change over between GMT and BST twice a year, which kicks a bloody big hole in't'owd sundial timekeeping.
Second: as summer lengthens, shadows shorten - it's no good having a pebble stuck where winter noon is when your summer shadow is feet off it.
Thirdly. We lie north of the equator, so your east-west sundial line will follow a curve, not a straight line. Other than that, I reckon you'll be fine. :

Ah, but the pebbles (two actually) are to point the west and east line over a period of time are they not? Is that not a reliable fact? Surely the length is immaterial summer or winter as long as it's discernible?

Your north and south pebbles (call them Norman and Scotty) will be in straight line.
But 'Enery and Wesley pebbles won't be. Each and every day they will move. Starting in winter they will be up near Norman's latitude and far away, but as summer comes they'll move nearer Mr. Stick and descend (like teenage bollox) towards Scotty!

Ah, right. I'm off to buy another pocket compass...

Magnetic north is changing faster than ever before so although still 'fairly' accurate it is moving by 30 miles per year. Experts are predicting it may be about to flip to the south pole soon. Apparently this happens around every 400,000 years but it is 780,000 years since it last flipped. According to this article, it takes around 10,000 years so you should get some use from that compass for a few years yet.

https://www.mnn.com/earth-matters/clima ... nal-pole-r

D'y'all reckon Ken Anderson's bought a stake in the North Pole?

[TANGODANCER]

A simple question just for my interest Spots/anyone who can answer (please respect the spirit in which it is asked as a Christian) : Regardless of curvature, In which direction does Jerusalem lie in relation to the UK (specifically Bolton, but UK will do) when facing forward. It seems, on a flat map to be roughly South East .