I was told the other day that due to the curvature of the earth the furthest you can see is 17 miles, can anyone confirm this?
cheers
Matt
cheers
Matt
Earths Curvature
- Thread starter Lithril
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My Guess it is wrong I have seen ships and other things over sixty miles away from Black mountain, and loads of other things as well.
When I get up early and face east the furthest thing I can see is about 93,000,000 miles
(it's the sun)
When I get up early and face east the furthest thing I can see is about 93,000,000 miles
(it's the sun)
dunno, but I would imagine it depends on your altitude. Perhaps that's 17 miles at sea level?
Also, the earth aint round, it's an elipse, so the value will be different for different points on the surface.
Also, the earth aint round, it's an elipse, so the value will be different for different points on the surface.
I don't know what the geometry of this is, but if at the beach you should be able to see further than the geometrical distance due to the weird properties of light.
At Dover you can see Calais relatively easily and that's about 15 miles isn't it? so i suspect the actual distance you can see is greater than 17, and it may also depend on the weather?
At Dover you can see Calais relatively easily and that's about 15 miles isn't it? so i suspect the actual distance you can see is greater than 17, and it may also depend on the weather?
Surely not right. I can see Swanage from a beach on the IoW, so that's not due to elevation???Lithril said:
Martyn said:
Have you got any data for that Martyn??
Cheers for the quick reply everyone, the reason I ask is that I've just started teaching the Solar System topic to some year 7 (11-12 year old) students and was after something a bit different to tell them.
Cheers
Matt
if you imagine the earth is a perfect sphere, has no atmosphere and your eyes are precisely at the surface, then you won't see squat.
bushtuckerman said:
Absolutely true! There are "weird optical effects and the Dover strait is a good example. You will appreciate i'm most often standing on the other shore
.Some days "Perfide Albion" is a mere shadow in the distance. On other days it looks as if you could spit on it. I' ve seen the cars drive on top of the Dover Cliffs from a sand dune in Ambleteuse (near Boulogne). It's a strange feeling how, depending on the weather, Britain is moving further or closer;
I knew there was an advantage to being a Viking. My World is flat and I can see all the way to the edge. .... 
Wayland said:I knew there was an advantage to being a Viking. My World is flat and I can see all the way to the edge. ....
and you can have cool viking websites
I've read (in Stephen Jay Gould) that at eye level above sea level, the horizon is about 20 miles away. Its one of the reasons sailors always knew the earth wasn't flat, as a ship would begin to disapear at that distance, hull first, mast last.
Pappa
Pappa
40km rings a bell with me that works out to 25miles this about the maximum distance microwave telecoms towers can be apart they send out a straight beam of microwaves so need repeating to follow the curvature of the earths surface
James
James
It's generally accepted that the farthest naked eye object is M31, the Andromeda galaxy which is 2.9 million light years away.[size=-1]SMARTY said:
[size=-1]Oh, and to be really picky, the Earth is a tri-lobed oblate spheroid.[/size][size=-1]Martyn said:
As for surface distance due to curvature, check out: http://www.imagiverse.org/resources/howthingswork/horizon/
Of course, when you add back in the surface features and atmosperic refraction there's local variability.
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That comes out as 4.8 Km (3 miles) from eye level to the horizon.Povarian said:
And that comes out as 4.8 Km too.bushtuckerman said:
3 miles doesn't sound right to me. There are landmarks (or should that be seamarks) at sea that I know to be further than 3 miles away, and yet I can clearly see them from top to bottom, without the horizon obscuring part of the view.
There's some interesting stuff about atmospheric refraction here:
http://en.wikipedia.org/wiki/Atmospheric_refraction
Pappa
This page:
http://mintaka.sdsu.edu/GF/explain/atmos_refr/horizon.html
suggests the distance could be very highly variable depending on a huge ammount of factors, but quotes reliable observed distances of several hundred miles.
http://mintaka.sdsu.edu/GF/explain/atmos_refr/horizon.html
suggests the distance could be very highly variable depending on a huge ammount of factors, but quotes reliable observed distances of several hundred miles.
Yup, that's what the maths gives.
I thought I'd sanity check with Dover to Calais (21miles). Dover cliffs are approx 100m giving approx horizon distance of 36km (22.37 miles) This accords with my memory of only just being able to see Calais from there. Add in refraction (mirages anyone) and that can throw the results significantly.
Edit: Ah! Just seen your last post - good link.
I thought I'd sanity check with Dover to Calais (21miles). Dover cliffs are approx 100m giving approx horizon distance of 36km (22.37 miles) This accords with my memory of only just being able to see Calais from there. Add in refraction (mirages anyone) and that can throw the results significantly.
Edit: Ah! Just seen your last post - good link.
