# How can I figure out what point is exactly halfway around the world from another point?

Asked by Jeruba (44872) August 9th, 2011

If I don’t have a physical, spherical globe with a world map on it, how can I tell what place is halfway around the world?

Is there a website where I can put in a location or coordinates and compute the opposite point on the globe?

I tried using Google to answer this, but I must not have come up with the right search terms.

Observing members: 0 Composing members: 0

Hope this is what you’re looking for
Now I’m gonna check… the opposite of where I am is… water.

linguaphile (14270)

Thanks, @linguaphile. That does seem to find the point that is literally opposite. And now I guess what I really meant was the point in the same hemisphere or at the same latitude. Opposite to me is water too, and that’s not what I was after. But I was able to move the maps around and make a pretty good approximation.

What search terms did you use to find this?

Jeruba (44872)

You’re welcome, @Jeruba! I think if you used the longitude the program gives you, but your own latitude, you’d find what you’re looking for.
I used “longitude latitude opposite”

linguaphile (14270)

I put it on the map as Jeruba (opp). It puts you on the eastern coast of China near Weihai. I just flipped the longitude from negative to positive.

jrpowell (40429)

Very cool, @johnpowell. But is the negative/positive flip definitely the right answer? Doesn’t that just place me an equal distance from the Prime Meridian in the other direction rather than 180 degrees around the circumference?

Jeruba (44872)

You could also use GMT times to approximate the opposite point from your area. If you are at a place where the local time is 1:00 PM look for the place where the local time is 1:00AM. However using longitudes and latitudes would be far more accurate.

raven860 (2158)

I fixed it. It is actually putting you in Iran.

edit :: Since your long is -121.928715705872 I just added 180.

jrpowell (40429)

There indeed is a website for this. I can’t remember what the site address is though. Try searching “antipode” or some variation thereof.

prioritymail (1627)

This site seems to do what you want using maps rather than coordinates.

flutherother (25729)

@Jeruba I’m curious. Why do you want to know? Are you digging a hole?

Sunny2 (18750)

@Sunny2, what a temptation to reply with a romantic fiction. But no, in actuality it’s because an acquaintance whom I don’t know very well (and feel a little put off by) mentioned that he now lives exactly halfway around the world from his birthplace. Since I’m curious about where he’s from but haven’t felt like asking, I figured that I could find out by computing what’s halfway around the globe from our present locale. And Iran would be a logical answer.

When I was about 8 or 9, I did persuade the neighborhood kids that we could dig a hole to China. We all thought that sounded exciting, and so we made a great start, right beneath a big old oak tree. Suddenly we encountered an angry red claw reaching up for us. “It’s the devil’s hand!” I screamed. “Quick, fill the hole!” What a heart-pounder that was. Narrow escape! We never tried it again.

Jeruba (44872)

@Jeruba What was the red claw? A crawdad? A scorpion? A red chicken foot? I’d be scared too!

Sunny2 (18750)

No, my dear, it was a root of the oak tree. I kind of think I realized that at the time, but I preferred the drama. Besides, I was getting a little tired of digging.

Jeruba (44872)

Isn’t it fun to reminisce? Thanks for sharing. I love the visual picture I get.

Sunny2 (18750)

or