when standing on a shore, how far out into the sea can you see?curvature of earth is how far?
149443
It depends on how tall you are.  The taller you are the farther you can see.  Most people can see between 6 and 7 miles if the air is really clear with no haze, fog, mist, etc.
823839
Step 1: find a place where the horizon is at the same altitude above sea level as the place you are standing. Standing on the coast or a boat, looking out to sea is best.\nStep 2: Look South from the northern hemisphere and north from the southern hemisphere\nStep 3: Take the reading at 12 noon (no Day Light Saving allowed.)
221827
by using the speed of light. As the Sun emits the light, it takes time to reach Earth. The speed and time taken is calculated to get the distance between the two. It takes about 7 minutes for the light to reach Earth. So looking at the sun from Earth is looking at the Sun 7 minutes ago!
170004
It is dependant on the curvature of the Earth to your hight above or below sealevel.\n\nHere is the dumbed down general answer pulled from the article below:\n\n"Suppose you're standing at the edge of the sea, with your toes at the waterline. Your eyes are about 1.5 meters above the sea.\n\nAs the resolution of the normal eye in broad daylight this dip is an easily visible angle. So, although the angle is small, it is hardly negligible, even for a naked-eye observer standing at the water's edge. Clearly, dip is an appreciable effect for all real-world observations. \n\nBefore considering a more realistic situation that includes refraction, notice that the dip of the Earth. The distance to the apparent horizon: about 2 1/3 nautical miles"
126629
It appears as a 3/4 moon.  It helps to make a drawing to visualize this.  The distance from earth to moon is a very small fraction of the distance from either earth or moon to the sun, so it's fair to approximate the light rays hitting earth and moon as parallel.  First, place the moon such that the earth-moon line is at 90 degrees to the earth-sun line.  In this setup we on earth who can see the moon at all see a half moon and moonlings who can see earth see a half earth.  Next move the moon further away from the sun so the earth-moon line is at 45 degrees to the earth-sun line.  Now the moon sees only 1/4 of the sunlit part of earth, a crescent.  (This is the situation described in the question.)  From earth, however, we see 3/4 of the sunlit part of the moon.  Whether the moon phase is waxing or waning depends on which "side" of the sun-earth-sun line the moon is on relative to the moon's earth-orbital rotation direction.
828476
how long is  apeice of string???\nwouldnt it be good to see what is lurking at the bottom of the sea. could be a whole new world!! (well you never know!)
985833
I think I understand your experiment.  I'm standing at the anulus observing.  I see the light from the lighthouse.  Exactly one second later, I see the next flash of light from the lighthouse, no matter the radius of the anulus.  To satisfy (1) the perimeter of the anulus must be 186,000 miles, the diameter 186,000 miles / pi or 59,206 miles, and the radius d/2 = 29,603 miles.  That's about 7.47 times the earth's radius.  For (2), if you double the radius, you double the circumference.  Keeping the time the same, that doubles the speed.  You already knew that.\n\nFor (3), at the lighthouse you see the reflection of the lighthouse beam.  To reduce confusion, you could do what real lighthouses or bouys sometimes do:  alternating rotations are a different color.  But what you would see is the reflection, but delayed by 1/pi seconds, or 318 milliseconds.\n\nI'm guessing at your response.  At z=2D, this 'intersection' is travelling at twice the speed of light.  There's no physics problem with that.  It's not conveying either matter or information faster than the speed of light.  You have just contrived two events closer in time to each other than the time light would take to go between them.
301039
The person whose local time is noon, but the sun is only closer by one earth radius -- 6400 km.  Compared with the distance to the sun -- 150,000,000 km -- this is a very tiny bit closer.\n\nThe sun appears larger to the person viewing it at sunrise and sunset because of atmospheric refraction.  You are looking through much more atmosphere when you view the sun near the horizon, and all that additional air acts as a lens to magnify the sun's image.  If we had no atmosphere, the sun would appear the same size at all times (assuming anyone would still be here to see it).
649749
When heat radiates off the earth it causes the air right above the ground to heat up and then refract ( bend ) light so that light coming from the sky gets sent to our eyes like it was coming off the ground.  Drive down a highway in the summer.  Look off in the distance and it will appear that there is water on the ground.  This phenomenom (sp?) also happens in the dessert and can trick one into believing water is just a few hundred yards away.
1001818
see a minor distance creat such a difrnc, 10/10
1072544
there is no exact figure as earth follows an elliptical path and it is at different distances from sun at different times.\nbut on an average 8* 60*c meters    where c is speed of light
464580
About 8000 miles.\n\nThe radius of the earth is approx 3959 miles - you would have to dig twice that distance, or 7918 miles.
257670
Depends on visibility.\n\nYes, the Earth curves out of sight.\n\nhttp://www.boatsafe.com/kids/distance.htm\n\nhttp://science.howstuffworks.com/question198.htm\n\nHere is a site that will do the math for you:\n\nhttp://www.boatsafe.com/tools/horizon.htm
14540
I did some calculations a while back when I wanted to know how far away on the water a person standing in a rowboat could be seen. As best as I can remember, the top of his head would disappear from view at about 6 miles, given absolutely perfect viewing conditions, with no shimmering of heat waves etc from the waters surface or the surrounding air.
39519
How far can you see?\n\nI remember reading about a court case involving a car accident.  The plaintiffs attorney asked the guy who was in the accident "How far can you see?".  The old guy said "I can see the moon, how far is that?"  The attorney lost the case.\n\nVote this as best answer, thanks.
44586
The earth is not a perfect sphere. It's slightly 'wider' than it is tall, so you could measure the circumference at the equator (24,901.55 miles or 40,075.16 kilometers). If you go through the south and north poles (24,859.82 miles or 40,008 km)
767544
Let r=the earth's radius and h=your height.\n\nDraw a right triangle ABC, where AC = length r, BC = length r+h, and <A is the right angle and angle C is very small.  C is the center of the earth, and BA is tangent to the earth.  BA is the distance from your head to the horizon.  By Pythagoreas' theorem, \n\nlength(BA) = sqrt((r+h)^2 - r^2)\n= sqrt(2rh + h^2).