Saturn Corrects Its Reversal

   On Tuesday September 29th in a move that comes about annually, Saturn will once again reverse its direction from moving toward the west to moving toward the east.
   Since around May 11th Saturn has appeared to be moving westward (toward the right) rather then toward the east. This happens as the faster moving Earth catches up with and then passes by Saturn. This apparent westward motion of Saturn is known as retrograde motion and for Saturn it’s retrograde motion comes to an end during mid-September when Saturn resumes its normal orbital motion toward the east, or to the left as we view Saturn from the Earth.
   Since retrograde is a reference to motion and means backward or reverse motion, then the opposite of retrograde would be prograde motion. So it would be correct to describe Saturn as having resumed prograde motion. However you would probably get a blank look from those you say this to! So stick with “direct motion” or just say that Saturn orbits the Sun to the east as we see it from Earth.

   Saturn is located over the southern horizon after sunset local time. It is about 7-8o to the east from Jupiter.

   
   
   
   

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Moon – Jupiter & Saturn Conjunctions

   The waxing gibbous Moon, over the next two evenings (September 24th and 25th, will pass by two of the giant outer planets. The Moon will pass within about 2-3o from Jupiter and about 1-2o from Saturn.
   Off toward the eastern horizon is the innermost planet Mercury and the bluish-white star Spica in Virgo the Harvest Maiden.


   
   
   

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September Moon at Descending Node

   Wednesday September 23rd the 7-day old first quarter Moon crosses the plane of the ecliptic moving south. This is known as the descending node, one of two intersections the Moon’s orbital path (dark green line) has with the ecliptic.

   On the date of the descending node the first quarter Moon will be about 20o to the east from the heart of Scorpius the Scorpion, the reddish star Antares, and about 15-16o west from Jupiter.
   Mercury and Spica are still a couple of degrees apart but low above the horizon as the Sun is setting.

   
   
   
   
   

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Mercury- Spica & Moon – Antares

   Tuesday September 22nd shortly after sunset local time look toward the western horizon for the innermost planet Mercury to be about 1o from the bluish-white star Spica in Virgo the Harvest Maiden. The two should make for an interesting comparison in apparent magnitudes with Spica at 0.96 and Mercury with a -0.01 apparent magnitude.
   The nearly first quarter but still waxing crescent Moon will be about 7-8o from the reddish star Antares in Scorpius the Scorpion. Both are positioned over the southern horizon.

   
   
   

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Last Night Had It’s Hang-ups!

   Last evening was another opportunity to image the ISS as it passed over my part of the world. So I did!
   While out in the backyard I aimed my camera nearly straight up to get a picture of one of my favorite parts of the sky. This is near the star Altair in the constellation Aquila the Eagle. Near Altair is the ‘tiny’ constellation of Delphinus the Dolphin. Looking further upward from the kite or diamond-shape stars there is another smaller constellation, Sagitta the Arrow.
   If you find Sagitta use the two stars at the end as ‘pointer stars’ and they will direct your eyes to a neat little star cluster, Brocchi’s Custer, also known as the Coathanger Cluster.

   
   
   

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Sun Enters Virgo-2020

view_from_earth   Wednesday September 16th the Sun in its apparent eastward motion along the ecliptic, moves out of the constellation of Leo the Lion and into the constellation of Virgo the Harvest Maiden. This is the true or actual position of the Sun as opposed to the pseudoscience of astrology which usually has the astrological Sun one constellation ahead or east from the Astronomical Sun’s position.
   In a few days the Sun, according to astrology, will cross the ecliptic moving southward crossing from Virgo into the constellation of Libra the Scales. We know this day as the September equinox, which this year is on the 22nd.

   Read a little more about how astrology has the Sun incorrectly placed in a previous blog, and in another blog discussing the effects of precession.

   
   
   

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Moon-Venus Conjunction + M44

   Monday morning September 14th look eastward in the pre-dawn skies for the 26-day old waning crescent Moon to be about 4-5o from the planet Venus and about the same distance from the open star cluster M-44, the Beehive Custer.

   The trio should make for an interesting view with binoculars.
   
   
   
   
   
   

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Neptune at Opposition – 2020

   Friday September 11th the outer planet Neptune reaches a position in its orbit around the Sun when it is on the opposite side of the Earth from the Sun. This coincidentally is known as opposition, and it is an orbital position which only the planets further from the Sun than the Earth may reach.
   At opposition an object orbiting the Sun beyond Earth’s orbit rises and sets in a fashion similar to our Moon when it is at full phase, in that the object at opposition rises at sunset and sets at sunrise.
   Currently Neptune rises at sunset and by late evening is over the southeastern horizon. Neptune has an apparent magnitude of 7.88 so it is beyond unaided-eye visibility but could be visible with large aperture telescopes or with a camera.

   
   
   

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September Moon at Ascending Node

   Wednesday September 10th the 22-day old last quarter Moon will be crossing the plane of the ecliptic moving north. This is known as the ascending node, one of two intersections the Moon’s orbital path has with the ecliptic. The ecliptic is actually the Earth’s orbit, and the Moon’s orbit is inclined about 6o from the ecliptic. So there are two node intersections, the ascending and descending nodes.
   On the morning of the node crossing the 22-day old last quarter crescent Moon will be to the east of the reddish star Aldebaran in Taurus the Bull. If you are a late night type watch for the Moon to rise around midnight local time giving you an opportunity to see Mars, Saturn and Jupiter arranged across the sky.

   On the other hand if you are like me and an early morning type then look for the Moon to be high above the southern horizon an hour or two before the Sun rises. Venus will be over the eastern horiozn and Mars over the southwestern horizon.

   Does our Moon actually go around the Earth as many graphics show? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*
*Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)
   
   
   
   
   
   
   

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Mars 2020 Retrograde Loop

Mars Retrograde Loop
   About every 26 months, 780 days, the planet Mars appears to pause in its eastward orbital motion and for a period of time, about 72 days, move toward the west before again pausing and returning to its eastward orbital motion. This is known as retrograde motion, and is an apparent, not actual, motion that all planets beyond the Earth’s orbit undergo relative to the Earth’s orbital motion. All outer planets, dwarf planets, and asteroids will have a retrograde motion period each time the Earth moves past them. Picture two race cars circling a track. The innermost car, moving faster, passes the outer car and from the perspective of the inner car it could look like the slower moving car was moving backward.

   This year the planet Mars appears to pause in its orbit on September 9th within the constellation of Pisces the Fishes and then begins moving westward or in retrograde across the constellation of Pisces the Fishes. By Mid-November Mars will have returned to its eastward, or prograde, orbital motion.
   
      You could plot the retrograde motion of Mars on this equatorial star chart. It is part of a set of free star charts made available from the Department of Physics and Astronomy at Stephen F. Austin State University.

   The data tables below show position information about Mars. The first two columns are what will be used for plotting the changing position of Mars. R.A. is the Right Ascension or hour circle position of Mars and is in units of hours and minutes. This is similar to meridians of longitude on Earth except they are numbered from 0 to 23 and there is only east. Dec is the Declination of Mars and is degrees and minutes. Declination is like latitude with degrees north and south from the celestial equator.
    Distance is between the Earth and Mars and is shown using AU or Astronomical Units (93,000,000 miles 149,668,992 km). Ang. Diam is the apparent size, or angular diameter, the planet appears and is measured in units of degrees, minutes, and seconds. Scroll down the data to October 6th where you will see when Mars is closest to the Earth as evidenced by having the smallest distance of 0.4149202 AU.

.
   
   
Coordinate Positions for Mars


 September 2020
Day|       RA        |       Decl      |     Distance    |  Ang Diam  | VMag
 1 |   01h 48m 41.4s |   +6° 38' 48.9" |    0.4941852 AU |  00' 18.9" | -1.8
 2 |   01h 49m 07.4s |   +6° 41' 08.2" |    0.4902798 AU |  00' 19.1" | -1.8
 3 |   01h 49m 30.3s |   +6° 43' 13.7" |    0.4864417 AU |  00' 19.2" | -1.9
 4 |   01h 49m 49.9s |   +6° 45' 05.2" |    0.4826728 AU |  00' 19.4" | -1.9
 5 |   01h 50m 06.3s |   +6° 46' 42.6" |    0.4789754 AU |  00' 19.5" | -1.9
 6 |   01h 50m 19.4s |   +6° 48' 06.0" |    0.4753516 AU |  00' 19.7" | -1.9
 7 |   01h 50m 29.2s |   +6° 49' 15.3" |    0.4718040 AU |  00' 19.8" | -2.0
 8 |   01h 50m 35.6s |   +6° 50' 10.4" |    0.4683349 AU |  00' 20.0" | -2.0
 9 |   01h 50m 38.7s |   +6° 50' 51.5" |    0.4649470 AU |  00' 20.1" | -2.0
10 |   01h 50m 38.3s |   +6° 51' 18.5" |    0.4616430 AU |  00' 20.3" | -2.0
11 |   01h 50m 34.5s |   +6° 51' 31.4" |    0.4584258 AU |  00' 20.4" | -2.1
12 |   01h 50m 27.2s |   +6° 51' 30.4" |    0.4552982 AU |  00' 20.6" | -2.1
13 |   01h 50m 16.4s |   +6° 51' 15.4" |    0.4522635 AU |  00' 20.7" | -2.1
14 |   01h 50m 02.2s |   +6° 50' 46.7" |    0.4493246 AU |  00' 20.8" | -2.1
15 |   01h 49m 44.5s |   +6° 50' 04.4" |    0.4464849 AU |  00' 21.0" | -2.2
16 |   01h 49m 23.3s |   +6° 49' 08.6" |    0.4437477 AU |  00' 21.1" | -2.2
17 |   01h 48m 58.8s |   +6° 47' 59.8" |    0.4411163 AU |  00' 21.2" | -2.2
18 |   01h 48m 30.8s |   +6° 46' 38.1" |    0.4385939 AU |  00' 21.3" | -2.2
19 |   01h 47m 59.5s |   +6° 45' 04.0" |    0.4361836 AU |  00' 21.5" | -2.2
20 |   01h 47m 25.0s |   +6° 43' 17.9" |    0.4338886 AU |  00' 21.6" | -2.3
21 |   01h 46m 47.2s |   +6° 41' 20.3" |    0.4317117 AU |  00' 21.7" | -2.3
22 |   01h 46m 06.4s |   +6° 39' 11.6" |    0.4296557 AU |  00' 21.8" | -2.3
23 |   01h 45m 22.5s |   +6° 36' 52.3" |    0.4277231 AU |  00' 21.9" | -2.3
24 |   01h 44m 35.7s |   +6° 34' 23.0" |    0.4259166 AU |  00' 22.0" | -2.4
25 |   01h 43m 46.0s |   +6° 31' 44.2" |    0.4242385 AU |  00' 22.1" | -2.4
26 |   01h 42m 53.5s |   +6° 28' 56.4" |    0.4226913 AU |  00' 22.1" | -2.4
27 |   01h 41m 58.5s |   +6° 26' 00.2" |    0.4212774 AU |  00' 22.2" | -2.4
28 |   01h 41m 00.9s |   +6° 22' 56.1" |    0.4199990 AU |  00' 22.3" | -2.4
29 |   01h 40m 00.9s |   +6° 19' 44.7" |    0.4188585 AU |  00' 22.3" | -2.5
30 |   01h 38m 58.6s |   +6° 16' 26.7" |    0.4178582 AU |  00' 22.4" | -2.5

Ocober 2020
Day|       RA        |       Decl      |     Distance    |  Ang Diam  | VMag
 1 |   01h 37m 54.2s |   +6° 13' 02.7" |    0.4170002 AU |  00' 22.4" | -2.5
 2 |   01h 36m 47.7s |   +6° 09' 33.5" |    0.4162868 AU |  00' 22.5" | -2.5
 3 |   01h 35m 39.5s |   +6° 05' 59.6" |    0.4157201 AU |  00' 22.5" | -2.5
 4 |   01h 34m 29.5s |   +6° 02' 21.8" |    0.4153021 AU |  00' 22.5" | -2.5
 5 |   01h 33m 18.1s |   +5° 58' 40.9" |    0.4150348 AU |  00' 22.6" | -2.6
 6 |   01h 32m 05.3s |   +5° 54' 57.7" |    0.4149202 AU |  00' 22.6" | -2.6
 7 |   01h 30m 51.3s |   +5° 51' 12.8" |    0.4149601 AU |  00' 22.6" | -2.6
 8 |   01h 29m 36.3s |   +5° 47' 27.2" |    0.4151563 AU |  00' 22.5" | -2.6
 9 |   01h 28m 20.4s |   +5° 43' 41.5" |    0.4155103 AU |  00' 22.5" | -2.6
10 |   01h 27m 04.0s |   +5° 39' 56.8" |    0.4160237 AU |  00' 22.5" | -2.6
11 |   01h 25m 47.1s |   +5° 36' 13.8" |    0.4166979 AU |  00' 22.5" | -2.6
12 |   01h 24m 30.0s |   +5° 32' 33.4" |    0.4175340 AU |  00' 22.4" | -2.6
13 |   01h 23m 12.8s |   +5° 28' 56.4" |    0.4185333 AU |  00' 22.4" | -2.6
14 |   01h 21m 55.8s |   +5° 25' 23.8" |    0.4196965 AU |  00' 22.3" | -2.6
15 |   01h 20m 39.1s |   +5° 21' 56.4" |    0.4210244 AU |  00' 22.2" | -2.6
16 |   01h 19m 23.1s |   +5° 18' 35.3" |    0.4225173 AU |  00' 22.2" | -2.6
17 |   01h 18m 07.8s |   +5° 15' 21.3" |    0.4241753 AU |  00' 22.1" | -2.6
18 |   01h 16m 53.4s |   +5° 12' 15.4" |    0.4259982 AU |  00' 22.0" | -2.5
19 |   01h 15m 40.3s |   +5° 09' 18.3" |    0.4279853 AU |  00' 21.9" | -2.5
20 |   01h 14m 28.5s |   +5° 06' 31.0" |    0.4301358 AU |  00' 21.8" | -2.5
21 |   01h 13m 18.3s |   +5° 03' 54.2" |    0.4324485 AU |  00' 21.6" | -2.5
22 |   01h 12m 09.7s |   +5° 01' 28.5" |    0.4349221 AU |  00' 21.5" | -2.4
23 |   01h 11m 03.0s |   +4° 59' 14.6" |    0.4375552 AU |  00' 21.4" | -2.4
24 |   01h 09m 58.2s |   +4° 57' 13.1" |    0.4403461 AU |  00' 21.3" | -2.4
25 |   01h 08m 55.6s |   +4° 55' 24.4" |    0.4432932 AU |  00' 21.1" | -2.3
26 |   01h 07m 55.2s |   +4° 53' 49.0" |    0.4463948 AU |  00' 21.0" | -2.3
27 |   01h 06m 57.1s |   +4° 52' 27.4" |    0.4496491 AU |  00' 20.8" | -2.3
28 |   01h 06m 01.5s |   +4° 51' 19.9" |    0.4530543 AU |  00' 20.7" | -2.3
29 |   01h 05m 08.4s |   +4° 50' 26.7" |    0.4566085 AU |  00' 20.5" | -2.2
30 |   01h 04m 17.9s |   +4° 49' 48.3" |    0.4603099 AU |  00' 20.3" | -2.2
31 |   01h 03m 30.2s |   +4° 49' 24.8" |    0.4641564 AU |  00' 20.2" | -2.2
 
November 2020
Day|       RA        |       Decl      |     Distance    |  Ang Diam  | VMag
 1 |   01h 02m 45.2s |   +4° 49' 16.5" |    0.4681463 AU |  00' 20.0" | -2.1
 2 |   01h 02m 03.0s |   +4° 49' 23.5" |    0.4722775 AU |  00' 19.8" | -2.1
 3 |   01h 01m 23.6s |   +4° 49' 45.8" |    0.4765481 AU |  00' 19.6" | -2.1
 4 |   01h 00m 47.2s |   +4° 50' 23.7" |    0.4809562 AU |  00' 19.5" | -2.0
 5 |   01h 00m 13.8s |   +4° 51' 17.2" |    0.4854998 AU |  00' 19.3" | -2.0
 6 |   00h 59m 43.3s |   +4° 52' 26.3" |    0.4901771 AU |  00' 19.1" | -2.0
 7 |   00h 59m 15.8s |   +4° 53' 51.0" |    0.4949860 AU |  00' 18.9" | -1.9
 8 |   00h 58m 51.4s |   +4° 55' 31.3" |    0.4999246 AU |  00' 18.7" | -1.9
 9 |   00h 58m 30.0s |   +4° 57' 27.2" |    0.5049911 AU |  00' 18.5" | -1.9
10 |   00h 58m 11.7s |   +4° 59' 38.7" |    0.5101834 AU |  00' 18.3" | -1.8
11 |   00h 57m 56.4s |   +5° 02' 05.6" |    0.5154994 AU |  00' 18.2" | -1.8
12 |   00h 57m 44.3s |   +5° 04' 48.1" |    0.5209372 AU |  00' 18.0" | -1.8
13 |   00h 57m 35.2s |   +5° 07' 46.0" |    0.5264944 AU |  00' 17.8" | -1.7
14 |   00h 57m 29.2s |   +5° 10' 59.3" |    0.5321689 AU |  00' 17.6" | -1.7
15 |   00h 57m 26.2s |   +5° 14' 28.0" |    0.5379582 AU |  00' 17.4" | -1.7
16 |   00h 57m 26.4s |   +5° 18' 11.7" |    0.5438596 AU |  00' 17.2" | -1.6
17 |   00h 57m 29.6s |   +5° 22' 10.6" |    0.5498707 AU |  00' 17.0" | -1.6
18 |   00h 57m 35.8s |   +5° 26' 24.2" |    0.5559886 AU |  00' 16.8" | -1.6
19 |   00h 57m 44.9s |   +5° 30' 52.5" |    0.5622108 AU |  00' 16.6" | -1.5
20 |   00h 57m 57.1s |   +5° 35' 35.1" |    0.5685347 AU |  00' 16.5" | -1.5
21 |   00h 58m 12.1s |   +5° 40' 31.8" |    0.5749577 AU |  00' 16.3" | -1.5
22 |   00h 58m 30.0s |   +5° 45' 42.2" |    0.5814774 AU |  00' 16.1" | -1.4
23 |   00h 58m 50.7s |   +5° 51' 06.2" |    0.5880915 AU |  00' 15.9" | -1.4
24 |   00h 59m 14.2s |   +5° 56' 43.3" |    0.5947978 AU |  00' 15.7" | -1.4
25 |   00h 59m 40.3s |   +6° 02' 33.3" |    0.6015942 AU |  00' 15.6" | -1.3
26 |   01h 00m 09.2s |   +6° 08' 35.8" |    0.6084785 AU |  00' 15.4" | -1.3
27 |   01h 00m 40.7s |   +6° 14' 50.5" |    0.6154490 AU |  00' 15.2" | -1.3
28 |   01h 01m 14.7s |   +6° 21' 17.1" |    0.6225036 AU |  00' 15.0" | -1.2
29 |   01h 01m 51.3s |   +6° 27' 55.3" |    0.6296406 AU |  00' 14.9" | -1.2
30 |   01h 02m 30.4s |   +6° 34' 44.7" |    0.6368584 AU |  00' 14.7" | -1.2
 


   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.


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