Expert: James Gort - 1/13/2009

Question
Hey James,
Every clear night for the last week or so (could be longer can't say I've purposely looked out at it) I've seen a bright object (star?) in a southwestern position from my house.
I live in the midlands in England if that will help at all.
I'm just curious, because I don't really see many stars where I live.  Also, it seems to be travelling quite fast across the night sky from a south of SW position to a point closer to the west.
Thanks :)
Stephen

Answer
Hello Stephen,

The object that's caught your eye is actually not a star at all, but the brightest planet there is - Venus.  Venus is always very brilliant - appearing about 16 times brighter than the brightest star in the sky (Sirius), but because Venus has a closer orbit to the Sun than earth does, it sometimes appears very close to the Sun in the sky, so it's harder to see.  And sometimes it's only visible in the daytime (with a small telescope, you can easily find Venus even in the daytime).  

But what makes Venus "stand out" now is that it appears almost at its most distant from the Sun - about 47 degrees -  which makes it more visible in the evening twilight.  Venus is always fairly close to the Sun in the sky, appearing in the Southwest in the evening (before sunset) or in the Southeast in the morning (before sunrise).  However, on January 14th, it reaches 47 degrees from the sun in the evening, which makes it visible higher in the sky and visible longer before it finally sets.

It's not really "travelling", but appears to move as the earth turns on its axis.  You're probably comparing it to stationary objects in the distance (trees, buildings, etc.), so Venus appears to be moving as it makes its way towards setting in the west.

Cheers,

Prof. James Gort