Though Venus, which is the brightest object in the sky after the Sun and the Moon, is usually referred to as either the morning or the evening star, the distinction belongs to both Venus and Mercury. Being between us and the sun, neither can appear opposite the sun in our sky and thus are either seen to the east in the morning or to the west in the evening.
Posts: 8089 | Location: in the backwoods of North Carolina | Registered: 06-07-02
coldfuse is absolutely correct but just to tweak his answer... since the earth is rotating, the stars, planets, and sun, appear to circle the earth. since venus and mercury are closer to the sun than us, they make appear to circle the earth at about the same time as the sun ( a little before it or a little after it at different times of year). since the sun is so bright, we can't see them for most of the day. but when one of them is just ahead of the sun it will pop up over the horizon just before sunrise be visible until the sun lights up the sky. If one of them is just behind the sun, it will be visible just after the sun has set, but it will then follow the sun and also set. since planets are brighter (because of how much closer they are) than stars, these planets are visible when the sky is still slightly lit up at late dusk and early dawn.
Also, as read in the book 'Planets' (205 pages I think {published recently}) neither Mercury nor Venus can be seen later than 3 hours after the sun has set and earlier than three hours before sunrise.
