i know venus is caleed morning/evening star, but is there any time where i can see it all night long?

Besides the Sun and the Moon, Venus is the brightest object in the sky. It cannot be seen in the middle of the night. But you can try and spot it near the horizon at sunrise or sunset.


It seems we should see Venus through all the night because Venus is inner planet.

For the inner planet, it never gets very far away from the Sun. The further in the planet is, the closer to Sun (in the sky) it is. There is a maximum angle between the Sun and the planet in the sky and that happens when the planet subtends a right angle between Earth and the Sun. This is called the greatest elongation and in the case of Venus, it is something like 46 degrees. Hence, the maximum Venus can get from the Sun (either in the morning sky or the evening sky) is 46 degrees and hence Venus always sets in less than about 3 hours after sunset or rises no earlier than 3 hours before sunrise.

No. Since Venus is closer to the Sun than us it can never get more than about 50 degrees away from it in the sky from our perspective. To be visible all night long an object has to be capable of getting close to 180 degrees away from the Sun (this is called opposition). The planets further from the Sun can do this, as of course can stars. The Moon is there when it is Full.

Nope..

No. Venus is always 1-2 hours before sunrise or 1-2 hours after sunset.

Right now Jupiter is out half way up in the South skies right after sun down. It can be seen til about mightnight.

You will never see Venus all night long because its orbit is inside Earth's orbit. At best, you will be able to see it around midnight, but then it will be barely above the horizon.

As for Web sites that tell you what planets are visible on a given night, there are a bunch of them. I'll find one if there isn't already one listed when I post this.

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OK, the following site is a good one for nighttime viewing. Not only will It tell you what planets are visible, it describes other events, such as the meteor shower coming up this weekend.

http://www.space.com/spacewatch/sky_calendar.html