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[Chicago Astronomer - Astro Joe]

Lunar Disk to meet up with Mars and Saturn

July 5th & 7th 2014

Two very nice pairings (or Conjunctions), of the Moon and two planets will be visible from the Chicago area this coming week...and if the skies are clear, it's a great time to grab your binoculars and aim your telescopes to catch two celestial bodies slide past each other.

On Saturday, July 5th, the 1st quarter Moon will join the reddish Mars in our southern skies - about 1/2 degree of separation from each other.  The farther south the observer is, the closer the meeting of the two.

And on Monday, the 7th of July, The Moon will visit another planet, this time Saturn, but with a larger separation of about 1 degree - but still will make a nice coupling.

Hopefully we will have clear skies and enjoy these conjunctions - take pics if you can and share them with us here.

[Centaur]

Jul 3, 2014 10:08:09 GMT -6 Chicago Astronomer - Astro Joe said:

...the 1st quarter Moon...

It's really nice of you to post that alert for folks, Joe. The Moon and planets will indeed be putting on a good show during the coming days. That's why I was hoping to schedule a Turner Camp star party for July 5.

But yikes, Joe! The Moon will end the first quarter of its current lunation and enter the second quarter of that lunation during the morning of July 5. So that evening it will already be in its second quarter. What's posted on calendars is the date for the end of the first quarter of a lunation when the Moon is elongated by 90° (quarter circle) from the Sun. At that time what we see in the sky is a Half Moon (half of its apparent disk illuminated). That's what it has long been called by most people. Wide usage determines definitions. 

The proper astronomical term for 90° elongation from the Sun of any solar system body is quadrature. Astrologers call it quartile. A week later when the Moon is elongated by about 180° (half circle) from the Sun we see a Full Moon in the sky, not a Half Moon. A "Quarter Moon" would be a crescent with 25% of the Moon's apparent disk illuminated. But I wouldn't apply the term that way either, since it has the potential for ambiguity.

Sorry, Joe, but I get into this because the use of jargon in any specialty (and especially its misuse) confuses laymen. Language is supposed to communicate, not obfuscate. They see first or last (or third) quarter on a calendar and are surprised by a Half Moon appearing in the sky. German's do it right and post Halbmond (Half Moon) on their calendars. Unfortunately some years ago English language calendar makers started abbreviating "end of the first quarter of the Moon's lunation" to simply "First Quarter" (but never "First Quarter Moon"). Half Moon is what I post in the calendars on my website that you reproduce here. I realize that you are not alone in the use of the term Quarter Moon, but please join me in helping to promote clearer astronomical language for laymen. We wouldn't want the residents of Half Moon Bay, California to have to rename it Quarter Moon Bay.

[Chicago Astronomer - Astro Joe]

Curt,

I dig all your fine edged tweaks and support.

Righteous.

[Centaur]

I've created a diagram that shows how the Moon and Mars will appear at their closest angular approach on July 5 as viewed from the Adler Planetarium.

[Paulie pchris00]

It was cloudy every time I looked outside last night.