what is the bright light in the eastern sky?

bb12

was up late tonight and just before going to bed noticed a very bright light in the eastern sky...initially thought it was an airplane coming to land at dublin but it's not moving...it looks like an extra bright star but have never seen anything like it before in the eastern sky...any ideas what it is?---nevermind, just googled and discovered it's venus...never knew she was in the eastern sky

ps200306

bb12 wrote: »

was up late tonight and just before going to bed noticed a very bright light in the eastern sky...initially thought it was an airplane coming to land at dublin but it's not moving...it looks like an extra bright star but have never seen anything like it before in the eastern sky...any ideas what it is?---nevermind, just googled and discovered it's venus...never knew she was in the eastern sky

Excuse my crappy drawing, but here's what you're probably more used to seeing:



Venus is a so-called inferior planet, that is, it orbits closer to the Sun than us. At one side of its orbit it is at what we call maximum eastern elongation. That means when the Sun sets in the west Venus is trailing behind it and so we see it in the evening twilight.

It takes 16 weeks for Venus to do half an orbit, so four months later it's on the other side of the Sun, going down in the west before the Sun in daylight hours so that we can't see it. What we do see is Venus coming up in the east before the Sun:



I've exaggerated the elliptical nature of Venus's orbit which is much more of a flat line from our perspective. Also, its tilt relative to our local horizon depends on the time of year and our location on the earth's surface. However, hopefully you can picture that when Venus is at maximum elongation (either east or west) it is moving more directly toward or away from us on that orbit. This means Venus seems to hang in the eastern or western sky for weeks without moving very much relative to the Sun.

But as the orbit takes it closer to the Sun from our perspective it is also travelling more transverse to our line of sight. So it seems to move more rapidly from night to night, until it gets too close to the Sun for us to see it in a dark sky. That's why -- especially if we're not paying close attention every night -- Venus seems to suddenly pop out as an evening or morning star, stay there for a few weeks and then disappear from view until we catch it again on the other horizon.