PDA

View Full Version : Moon Occults Venus - North America - Daytime - Dec 7



Centaur
2015-Nov-29, 07:24 PM
The 13% illuminated waning crescent Moon will occult the brilliant planet Venus for observers in North America during the daytime on Monday 2015 DEC 07. Venus is visible by naked eyes amid daylight, but a telescope would be immensely helpful. Avoid looking at the Sun.

Immersion will occur on the lunar bright limb and emersion on the dark limb. Telescopic observers on a graze path will witness a partial Venus in the background as lunar hills and valleys pass by. Observers between the two graze paths will see a full occultation.

I’ve created a graze map, preview graphic with data ideally for observers at Chicago’s Adler Planetarium, and a set of Besselian elements. They can be seen by first going to my astronomy webpage: www.CurtRenz.com/astronomy.html . Then click The Moon followed by Lunar Occultations.

Photos and descriptions of the event would be welcome additions to this thread. If you would like specific occultation or graze predictions for your location based on precise numerical integration, please reply to this post with your longitude, latitude, elevation and time zone.

mapguy
2015-Dec-01, 12:36 AM
Thanks for the info, Curt. Could I please get the times of immersion and emersion for my location?
North 39.67604, West 104.95296
Elev. 5389, Mountain time zone

Centaur
2015-Dec-01, 01:16 AM
Thanks for the info, Curt. Could I please get the times of immersion and emersion for my location?
North 39.67604, West 104.95296
Elev. 5389, Mountain time zone

mapguy, for your location I predict that the immersion of the center of the full disk of Venus will occur at 09:35:51 MST with emersion at 11:13:10.

Good luck! Verification of the predicted timings would be appreciated. :)

chornedsnorkack
2015-Dec-01, 06:10 AM
I observe that while graze paths are depicted, rising and setting edges are not.

ngc3314
2015-Dec-06, 06:33 PM
Thanks for calling this to our attention. Now if the weather will just cooperate...

I looked up our local circumstances using Guide, and was puzzled at the long duration at our near-central location until I realized that Venus moves over 4 arcminutes during the occultation. A solar system full of moving objects.

Centaur
2015-Dec-06, 11:12 PM
Thanks for calling this to our attention. Now if the weather will just cooperate...

I looked up our local circumstances using Guide, and was puzzled at the long duration at our near-central location until I realized that Venus moves over 4 arcminutes during the occultation. A solar system full of moving objects.

You're welcome. I'll see what I can do about the weather. ;)

The motion of Venus is indeed a factor. Another is the rotation of the Earth making the Moon appear to move more slowly against the celestial background for an observer on the Earth's surface than as viewed by X-ray vision from the Earth's center.

tony873004
2015-Dec-07, 05:44 AM
...until I realized that Venus moves over 4 arcminutes during the occultation. A solar system full of moving objects.
Here's a sim you can run in your browser that shows just how much both Venus and the Moon move during this event. This illustrates the lengthening of the event. It's set for San Francisco, but you can choose your city from the list, or enter your Lat & Lon.
http://orbitsimulator.com/gravitySimulatorCloud/simulations/1449465767095_MoonOccultsVenus2.html



...Another is the rotation of the Earth making the Moon appear to move more slowly against the celestial background for an observer on the Earth's surface than as viewed by X-ray vision from the Earth's center.
Here's a simulated image showing just how much the rotation of the Earth affects the Moon's position. Each cycle represents 1 day. A viewer with X-ray vision in the center of the Earth would see a straight line Moon path.
http://orbitsimulator.com/BA/moonPath.png


I'll see what I can do about the weather. ;)

Can you fix San Francisco too? I'm going to try to take my Physics class outside tomorrow morning to show them. Disappearance happens 7 minutes after the start of class. But right now it is raining!

schlaugh
2015-Dec-07, 05:17 PM
About T-minus 25 minutes here in Atlanta (the occultation starts at 12:42 local). We're lucky to have clear skies and mild temps.

I tried to set up the Dob to snap some afocal photos - and ran into alignment issues. The scope was last out of the bag a few years ago and yes I should have known better. So I grabbed my collimator laser - and of course dead batteries, the button type found on battery stands in some stores.

*sigh* Back to binocs.

schlaugh
2015-Dec-07, 05:35 PM
Hmmm...Venus disappeared (as far as I can see) at 12:33 EST. I'm using my phone for the time hack.

ETA: Not sure where I picked up that 12:42 time. Clearly that's incorrect, or may have been correct for some other location. But not here.

Centaur
2015-Dec-07, 05:52 PM
Hmmm...Venus disappeared (as far as I can see) at 12:33 EST. I'm using my phone for the time hack.

My predictions for Atlanta (W 84.39050 - N 33.79590 - 100 m) were immersion of the center of the full disk of Venus at 12:32:45 EST with emersion at 13:58:05.

schlaugh
2015-Dec-07, 06:04 PM
My predictions for Atlanta (W 84.39050 - N 33.79590 - 100 m) were immersion of the center of the full disk of Venus at 12:32:45 EST with emersion at 13:58:05.
Thanks Curt, that's spot on! I'll be looking for emersion after lunch.

ngc3314
2015-Dec-07, 06:31 PM
Good weather in the Southeast for the event. Here are some frames from a video during immersion, using the University of Alabama 0.4m campus telescope - wasn't sure how well we could see the sunlit limb of the Moon. Now off to try emersion.

21162

schlaugh
2015-Dec-07, 07:12 PM
And Venus reappeared for me at 1:58:20.

Nice photos ngc!

mapguy
2015-Dec-07, 11:55 PM
From what I could tell, generally speaking, the southeast was the only cloud-free area in the continental US during the occultation.
Eager to see other photos/videos that people were able to obtain.