Just scale the uvs to match.
Go to the uv window and select all the points (A Key). Then scale them (S Key) and lock it so they only scale up and down, which is the Y coordinate (Y Key). Then you should be able to scale it by just moving the mouse. But to make it accurate you can lock the scaling to 0.1 intervals by holding CTRL, so do that and scale it 2.0 times on the Y axis. Then to get it back on the center of the uv window click on the menu right under the uv thing and click on UVs->Layout Clipped to Image Size, and then use G to move the vertices and they should snap to the center of the earth texture image. Then if you want you can unclick Layout Clipped to Image Size so you don’t forget and it doesnt cause problems. But that should be how you would do it…
If that still doesnt line up correctly then select the two halves of the sphere separately (Draw a box to select, B Key) and move them (G Key) and scale them (S Key) to match up