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11/28/2017 – Ephemeris – Though it appears bright, the Moon is pretty dirty

November 28, 2017 1 comment

Ephemeris for Tuesday, November 28th. The Sun will rise at 7:56. It’ll be up for 9 hours and 8 minutes, setting at 5:04. The Moon, 2 days past first quarter, will set at 2:44 tomorrow morning.

The Moon tonight is a waxing gibbous phase, and each night until it’s full it will get brighter and brighter, drowning out the fainter stars. The Moon is almost too bright to comfortably view in a telescope. One can get a moon filter for the eyepiece, or wear sunglasses or opt for higher magnification. It is after all daytime on the Moon and it’s essentially the same distance from the Sun as we are. A saving grace is that the Moon isn’t white. It’s a dirty gray, reflecting on average only 13.6 percent of the light it gets from the Sun. Just think how bright it would appear if it were 100% reflective, over 7 times brighter than it appears now. The face of the Moon hasn’t appeared to change at all since before we landed there 48 years ago.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Moon albedo comparison

Moon albedo comparison. Actually about 50% vs. 100%. The Moon is less reflectant than that.. Sunday’s super moon image created via Stellarium.

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11/06/2017 – Ephemeris – Taurus’ angry red eye, Aldebaran

November 6, 2017 1 comment

Ephemeris for Monday, November 6th. The Sun will rise at 7:27. It’ll be up for 9 hours and 57 minutes, setting at 5:24. The Moon, 3 days past full, will rise at 7:52 this evening.

Last night the Moon passed in front of or occulted the bright star Aldebaran. Above right of Moon tonight is Aldebaran the bright orange star with a V shape of other stars in the face of Taurus the bull. Aldebaran appears at the lower left tip of that letter V laying on it’s side. With the bright Moon, it might take binoculars to pull out the faint stars of the V. Aldebaran isn’t actually part of the group, called the Hyades star cluster. The cluster is about 153 light years away, while Aldebaran is 65 light years away. The star has an orange hue because its surface is cooler than the Sun’s. However Aldebaran is 44 times larger in diameter, and shines 425 times brighter than the Sun. The name Aldebaran means “Follower” because it follows the Pleiades star cluster above it.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Aldebaran

Aldebaran in the Hyades (unlabeled), with also the Pleiades, unlabeled, at the top and the Moon. at 9 p.m., November 6, 2017. Created using Stellarium.

11/05/2017 – Ephemeris Extra – There will be an Occultation of Aldebaran tonight*

November 5, 2017 1 comment

This posting will not be broadcast.

* Or tomorrow morning, depending where you are.

Ephemeris extra for Sunday, November 5th. The Sun will rise at 7:25. It’ll be up for 10 hours and 5 minutes, setting at 5:25. The Moon, 2 days past full, will rise at 7:01 this evening.

Tonight just after 8 p.m. the bright star Aldebaran will disappear at the left edge of the Moon. Aldebaran is angry red eye of Taurus the bull. The star will reappear at the dark upper right edge of the Moon. Start looking at 8 p.m. or before. Use binoculars or a small telescope to spot the star against the glare of the bright Moon. The star is nowhere as bright as shown in the illustrations below. Star appearances and disappearances appear instantaneous, unlike what the illustrations show.

Aldebaran Occultation begins at 8:07 p.m. EST (1:07 UTC Nov 6th)
Aldebaran Occultation ends at 9:00 p.m. EST (02:00 UTC Nov 6th)

Note the times are for the Traverse City/Interlochen area. It will vary by a few minutes for northern lower Michigan.  The position angles of the entrance and exit points of Aldebaran will also be different.

Otherwise use a planetarium program like Stellarium to preview the event. However, set the program for topocentric coordinates. In Stellarium that’s in the Configuration window, Tools Tab and check the Topocentric coordinates box. Topocentric coordinates are the apparent positions for your location on the Earth. So also make sure your location is correct. The geocentric conjunction of the two bodies will be November 6, 2:42.9 UTC, so it will occur after midnight on the morning of November 6th for locations in northern Europe and Asia.

Addendum

Occultation Map

Occultation Map for the occultation of Aldebaran by the Moon . Credit Occult 4 program from IOTA.org.

Occultation start

Aldebaran at the start of the occultation at 8:07 p.m. for the Traverse City/Interlochen area. Created using Stellarium.

Occultation end

Aldebaran at the end of the occultation at 9:00 p.m. for the Traverse City/Interlochen area. Created using Stellarium.

10/27/2017 – Ephemeris – Tomorrow night is International Observe the Moon Night in downtown Traverse City

October 27, 2017 1 comment

Ephemeris for Friday, October 27th. The Sun will rise at 8:13. It’ll be up for 10 hours and 24 minutes, setting at 6:38. The Moon, at first quarter today, will set at 12:44 tomorrow morning.

The annual International Observe the Moon Night will be observed this Saturday evening. Members of the Grand Traverse Astronomical Society will be stationed on the north side of the 200 block of East Front Street. Starting at 7 p.m. near Orvis Streamside and will be moving our telescopes eastward from time to time to keep up with the westward sinking motion of the Moon over the single story buildings to the south as long as we can. The moon will be a day past first quarter with lots of craters and lunar seas visible in telescopes. The society will also have some giveaway items from NASA for the young and not so young. The event will be canceled due to heavy overcast or other inclement weather.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The Moon

The Moon about as it would appear tomorrow night, October 28, 2017 at 8 p.m. Credit: NASA/Ernie Wright.

10/24/2017 – Ephemeris – Saturn and the Moon tonight

October 24, 2017 1 comment

Ephemeris for Tuesday, October 24th. The Sun will rise at 8:09. It’ll be up for 10 hours and 32 minutes, setting at 6:42. The Moon, 3 days before first quarter, will set at 10:09 this evening.

The crescent Moon will be in the southwest as it gets dark tonight. The planet Saturn will appear below and to the right of our satellite. Saturn has those gorgeous rings, which are visible at as low as 20 power scopes and hinted at lower magnifications. The Moon shows a fat crescent with two whole gray seas, Crises, nearest the limb, and below Fertility. Partially illuminated are Tranquility above and the small sea of Nectar. At the bottom end of that small sea is a horse shoe shaped crater called Fracastorius. It looks like the lava welling up from the Nectar asteroid impact washed down the walls of Fracastorius. The bottom part of the Moon is the lunar highlands of brighter rugged craters.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The Moon and Saturn

The Moon and Saturn at 8 p.m. October 24, 2017. Created using Stellarium.

Binocular Moon

The Moon at 8 p.m. October 24, 2017 as it might be seen in binoculars. Created using Virtual Moon Atlas.

 

10/13/2017 – Ephemeris – The bright star Regulus dips behind the Moon Sunday morning

October 13, 2017 1 comment

Note:  The original program recorded for this day was erroneous in the timing and appearance of this event.  Occurring about an hour later than reported here.  The Interlochen personnel may or may not replace the original program with the one below.  Also those who downloaded the audio from ephemeris.bjmoler.org before late Thursday night may have downloaded the incorrect mp3.

Ephemeris for Friday, October 13th. The Sun will rise at 7:55 a.m.. It’ll be up for 11 hours and 5 minutes, setting at 7:00 p.m. The Moon, 1 day past last quarter, will rise at 2:08 tomorrow morning.

On Sunday morning the Moon will pass in front of, or occult the bright star Regulus, the brightest star in Leo the lion. This will happen as morning twilight starts. Regulus will disappear at the left edge of the crescent Moon at around 5:47 a.m. A telescope or binoculars may be needed to spot Regulus. Go out at least 5 or 10 minutes early to make sure you can spot the star. Regulus will reemerge at 6:25 at the 11 o’clock position on the dark part of the Moon. Earth shine on the night side of the Moon may be bright enough to see its dark edge. Observers west of us in the United States except the northern most states west of Minnesota will also get a view. Those in specific locations in the northern tier of states will get to see Regulus just graze the north edge of the Moon.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Occultation start

Occultation of Regulus by the Moon disappearance at around 5:47 a.m. for northern Michigan. Created using Stellarium.

Occultation end

Occultation of Regulus by the Moon reappearance at around 6:25 a.m. for northern Michigan. Created using Stellarium.

Occultation Map

Map showing the locations where the occultation of Regulus will be visible. For the area bounded by heavy lines the occultation will occur at night. Click on image to enlarge. Credit: Occult4 by IOTA.

10/05/2014 – Ephemeris – The Harvest Moon

October 5, 2017 Comments off

This is Bob Moler with Ephemeris for Thursday, October 5th. The Sun will rise at 7:45. It’ll be up for 11 hours and 29 minutes, setting at 7:15. The Moon, at full today, will rise at 7:38 this evening.

This is the day of the Harvest Moon. It will rise just before sunset and colored like a huge pumpkin. The huge size is an optical illusion, and the coloring is courtesy of our Earth’s atmosphere selectively bleeding out the blue from the Moon’s light. The reason the Harvest Moon is so special is that during this period the Moon rises for quite a few days just before and in twilight, effectively lengthening the hours of light that farmers can have to harvest their crops. Tomorrow the Moon will rise 32 minutes later than tonight, rather than the average 50 minutes. The effect is a bit diminished this year because the Moon is nearing perigee, its closest to the Earth and is traveling a bit faster than average. The Moon can get down to a 25 minute day-to-day difference.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Harvest Moon

The position of the Moon for 7 nights centered on moon rise tonight (10/04/2017). The rotation of the Earth carries the Moon to rise parallel to the green celestial equator line. The brown area at the bottom is below the horizon. Click on the image to enlarge. Created using Cartes du Ciel (Sky Charts).