how to tell if its a bright star or a planet

[buc4933]

My question is if you see a bright star in the sky, how could you tell whether it is a star and not, for example Venus?

 

[nexium]

Stars twinkle more than planets.<br />Planets will move in relation to surounding star field.<br />but not as fast as satellites. Don't confuse the two as its inbarassing trust me on this. <br /> PS a star chart is helpful.

 

[CalliArcale]

Note for beginners: the fast relative motion against the background of fixed stars isn't all that fast. But you can see it for yourself by look at a planet in the sky each night for a week. Plot its position by hand; you'll definitely realize that it's moving relative to the stars. The more distant planets appear to move more slowly, but they do move noticeably. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[MeteorWayne]

Another pretty easy way to tell is to learn where the brighter stars are in the sky, and to learn where the "ecliptic" is. Since the solar system is very flat (except for Pluto, but you can't see that without a decent sized scope anyway), all the planets, the sun, and the moon move in a fairly narrow band in the sky.<br /> I demonstrate this for folks at my observatory by pointing my head at the north star, then sticking my hands straight out and spinning my upper body. (It's pretty funny to watch, but it's a lesson that is never forgotten <img src="/images/icons/laugh.gif" /> )<br />And since this is the sun's path across sky is what the constellations of the zodiac are named for, a planet will almost always be in one of those constellations. For example, Saturn in in Leo right now, Venus and Uranus are in Aquarius, Mercury and Neptune are in Capricorn, and Mars is in Sagittarius.<br />Most of these are farly bright and easy to learn constellations. It's also fun to watch them change throughout the year as we move around the sun.<br />Interestingly, Jupiter is in Ophiucus right now, which is not one of the Zodiac constellations, an error made by astrologers, who included this part of the ecliptic in with Scorpio. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[langolier]

Someone please correct me if I'm wrong, but I've always been under the impression that when using a pair of binoculars you could distinguish a planet from a star by how hard it was to "steady" in your view. Stars sit there relatively motionless but the planets tend to dance and hop around. In particular, I find that they have a bright "tail" behind them as they do this; which is much less apparent with the more distant stars.

 

[MeteorWayne]

Welcome to SDC!<br /><br />I can't think of any reason for what you are saying to be true. In fact if anything it would be the opposite.<br />Since a star is a point, it moves around a bit as the light is refracted by air parcels in the atmosphere.<br />A planet is a disc, so the movements average out across the disk.<br />That is why stars twinkle, and in general, planets don't.<br /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[langolier]

Thank you for the correction. I certaintly do observe this happening consistently with certain objects in the sky when I stargaze with just my binoculars and arms (to steady) though, so I am curious as to what those might be. They stand out from all the other stars because even the slight trembling of my arms causes them to jiggle and skip across my field of view to a much higher degree than anything else.<br /><br />I must admit I'm no expert (obviously) and infact, I don't think I even qualify as an amateur.

 

[MeteorWayne]

If you're looking at the skies with binoculars, you're an amateur astronomer <img src="/images/icons/smile.gif" /><br /><br />Where are you? <br /><br />Maybe I can suggest some good binocular targets! <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>