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Gonzales Weekly Citizen - Gonzales, LA
  • Looking Up: Planets parade after dusk

  • The most casual viewer of the night sky this winter cannot help to notice the dominance of planets Venus and Jupiter in the west.

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  • The most casual viewer of the night sky this winter cannot help to notice the dominance of planets Venus and Jupiter in the west.
    Following evening twilight and even before the sky is fully dark, these two brilliant planets stand out, piercing the deepening blue. Venus is the brighter of the two. As the planets continue their procession - that includes our Earth in its travels - Jupiter and Venus are appearing closer and closer together.
    They will be closest - in conjunction - on March 15, only 3 degrees apart (six widths of the moon).
    Joining the scene is the elusive planet Mercury, also very bright on its own, but harder to distinguish. Mercury, the closest world to the sun, never ventures far from the solar glare. During late February and March, look very low in the west below Venus around 30 or 40 minutes after sunset. If you wait much longer, Mercury will have set, as the darkening sky brings out Venus and Jupiter even more.
    The crescent moon adds to the solar system drama this week, night to night moving up and getting fatter (maybe it is made of green cheese...) as it climbs higher and higher. Watch as the moon glides past Venus and then Jupiter, on its way to first-quarter phase on Wednesday, Feb. 29.
    At this time the moon looks like a half. So why in the world is it called first “quarter”? It’s because the moon in its orbit is one-quarter away around, from new moon to full moon.
    A small telescope will show that Venus and Mercury also display phases, like the moon. Venus is currently showing a gibbous phase, like the moon will appear on its way from first quarter to full. In this case, Venus is rounding its orbit on it way to a growing quarter phase and finally as a crescent, on its way to “new” phase. All this time, Venus will appear as our “Evening Star.” This is only one-half of its orbit. When it is roughly between Earth and the sun and its back side is toward us, we normally can’t see it, as it is much too close to the sun. Astronomers have a 12-cylinder term for this: “Inferior conjunction.”
    Venus then slides into view once again in the morning eastern sky before sunrise, first as a crescent (as seen in a telescope), then a quarter phase and later as a gibbous. When Venus heads back behind the sun (or very close to it) it would appear in “full phase” facing right at us. Again, we never actually see this because the sun’s glare is too great.  At this time Venus is completely opposite from the Earth, on the other side of the sun - and this is known as “superior conjunction.”
    Page 2 of 2 - Venus takes 224.7 days to orbit once.
    Note that I mentioned that normally we can’t see Venus in inferior conjunction. This time around we can! On extremely rare occasions we can actually view the silhouette of Venus as it crosses the face of the sun (with safe precautions). A “transit” of Venus will be occurring June 5. More on this later.
    Mercury performs like Venus, but its loop is not as broad and is much quicker, being closer to our friendly star. Mercury zips around the sun once in 88 days.
    Jupiter, on the other hand, is farther away from the sun than the Earth and thus is called an “outer planet.” Planets farther out display little phase, except for a very slight gibbous, most noticeable with Mars. This is because of our long perspective; at certain times, the angle at which we see the outer planets show a little less of their full disc in our telescopes.
    Mars is visible in the east during the evening. The bright Red Planet is at conjunction March 5, rising at sunset and in view all night. Saturn may be seen low in the east around 11 p.m. and is much easier to see later on.
    Readers are welcome to send notes to news@neagle.com. Please mention where you read this column.
    Keep looking up!
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