The Moon and Jupiter Dance Tomorrow

Good day folks.

As I noted back in August, there will be an occultation of Jupiter by the Moon early Tuesday morning 7 Dec., 2004. This should be a wonderful sight for those motivated to view it. It will be naked eye visible but binoculars will make viewing it much better.

It could only be better if the disappearance were to occur from the dark side. As it is, Jupiter will slide behind the bright side of the crescent Moon to reappear about an hour later from the dark side. If you can catch the reappearnce in binoculars, it will be something to remember for a long time.

This event will be visible for all North America from the East Coast to the mid-West. Those in the east will have a better view as the Moon will be at a greater elevation above the horizon.

There are of course two events: 1) The disappearance. 2) The reappearance

1) The disappearance will be visible approximately as far west as the curved line from Amarillo, Tx., Dodge City, Ks., Grand Forks, ND, and Winnipeg, MB. These cities will have the Moon virtually on the horizon at the time of the disappearance. The further east you are the better the view. For example: Bangor, Me will have the Moon at 24º above the horizon, Albany, NY will have the Moon at 21º, Charleston, SC will have the Moon at 20º, Atlanta, Ga will have it at 16º, and Orlando, Fl will be at 22º.

2) The reappearance will be visible further west since the Moon has now had about 1 hour to climb higher in the sky. Cities as far west as Flagstaff, Az, Helena, Mt, and Provo, Ut will be able to see the reappearance if their local conditions allow them to see the true horizon.

To find the times that both events will occur for you, or a city near you, go to this URL:
[link to www.lunar-occultations.com]
The first table is the list for the disappearance event. The second for the reappearance.

An important note about the reappearance: Since Jupiter is behind the Moon it is difficult to guess where it will emerge at the calculated time. Also, since the Moon has had about an hour to move during the occultation it will have the appearance of having rotated due to perpective which further confuses a guess.

You will notice in the tables on the IOTA webpage a column labelled CA. This is the cusp angle of the event, either disappearance or reappearance. To use it to view the reappearance from the dark limb of the Moon you find the angle and note whether it is N or S. This is the arc for the reappearance measured from one of the two cusps.

For example, Reappearance:

Cleveland, OH: Time: 4:58:45am EST. Moon elevation = 26º. CA = 78ºN
At 4:58 and 45 seconds Jupiter will reappear from the dark edge of the Moon 78º from the Northern Cusp (upper point of the crescent). The 78º can be estimated if you consider that the whole disk of the Moon is 360º around. This would be about 1/5 around the disc starting at the northern cusp and measuring *into* the dark limb.

Durham, NC: Time: 5:00:51am EST. Moon elev. = 31º. CA = 88ºS
At 5:00 and 51 seconds Jupiter will reappear from the dark edge of the Moon 88º from the Southern Cusp (lower point of the crescent). The 88º is about 1/4 around the disc starting at the southern cusp and measuring into the dark limb.

The cusps will not be straight up and down, but rotated anticlockwise somewhat. The one that is more at the top of the Moon is the northern. This should get you pretty close to the emergence point with binoculars. Set your watch to the NIST at www.time.gov which will get you within a few seconds of actual time (server lag, etc.). A few minutes before reappearance find the approximate spot emergence with your binocs and note it so you can find it again. A minute before emergence start counting, "One thousand one, One thousand two, ..." and find the emergence point. If you have a table to rest your elbows, you should catch it. Maybe you´ll get lucky and see it winking in and out as it passes behind lunar mountains on its way to full emergence.

The WA (watts angle) is more important for astronomers as it measures the event from the true lunar north pole. The apparant rotation of the lunar features with time due to perspective is eliminated. And yes, astronomers do know that the lunar features appear to rotate throughout the night due to perpsective.

Lunar occultations happen all the time with various objects and it is a great hobby to view them. Some nights there are a dozen objects occulted by the Moon. Most of these are telescopic objects, but it is fascinating to view them. Then there are occultations of stars by asteroids, occultations of stars by planets, occultations of stars/asteroids by satellites, etc.

Amateur astronomers know of these things and observe them all the time. It is one of the ways it is known that celestial objects are *exactly* where they are supposed to be ... to the second.

These astonomical predictions via Maths are not a few minutes, hours or days off. Not months and years in error. They happen ***to the second*** unlike fringe-science/religious/ET predictions and statements that something is amiss in the heavens, so I ask the "Moon/Sun/whatever is too far North/South/East/West/High/Low/etc" to please desist as these things are being observed accurately every day to be in their proper positions. You can do it also if you are really interested in the truth of these matters.

Have fun tomorrow morning.


Reality