abstract:Transit passage is a concept of the Law of the Sea which allows a vessel or aircraft the freedom of navigation or overflight solely for the purpose of continuous and expeditious transit of a strait between one part of the high seas or exclusive economic zone and another. The requirement of continuous and expeditious transit does not preclude passage through the strait for the purpose of entering, leaving or returning from a state bordering the strait, subject to the conditions of entry to that state.
The reason astronomers want to observe reflected sunlight during the transit of Venus is to test whether they can detect the faint imprint of passage of the sun's light through the atmosphere of Venus.