September Moon at Perigee

   Our Moon reaches perigee, (closest to Earth), for this orbit, on Friday September 18st. At that time the Moon will be at a distance of 28.15 Earth diameters, 223,122 miles (359,081 km) from the Earth.

   On the day of the perigee Moon the 1.5-day old waxing crescent Moon will be over the western horizon near the innermost planet Mercury. Further to the east are Jupiter and Saturn.

   Does our Moon actually go around the Earth as this graphic shows? 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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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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Jupiter Corrects Its Reversal

jupiter-ani   On Saturday September 12th in a move that comes about annually, Jupiter will once again reverse its direction from moving toward the west to moving toward the east.
   For about the past 4 months Jupiter 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 Jupiter. This apparent westward motion of Jupiter is known as retrograde motion and for Jupiter it’s retrograde motion comes to an end on September 12th when Jupiter resumes its normal orbital motion toward the east, or to the left as we view Jupiter 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 Jupiter 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 Jupiter orbits the Sun to the east as we see it from Earth.
   Jupiter is located over the southern horizon after sunset local time. It is about 7-8o to the west from Saturn.

   
   
   
   

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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.

   
   
   

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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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)
   
   
   
   
   
   
   

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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Moon – Hyades Conjunction

   Spoiler Alert: This is an early morning thing! The 21-day old Waning gibbous Moon rises late tonight (September 8th) just before midnight and then will be visible above the horizon through the rest of the morning pre-dawn hours on Wednesday September 9th. During that time the Moon will be passing the open star cluster, the Hyades, and will be about 4-5o from the reddish star Aldebaran in Taurus the Bull. From mythology the v-shaped open star cluster is the face of the Bull while Aldebaran, with its reddish color, represents the ‘angry eye’ of Taurus as it prepares to attack.

   An open star cluster, like the v-shaped Hyades and the dipper-shaped Pleiades make for interesting views using binoculars, and especially when another celestial object passes by.

   
   
   

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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The Red Object Tour: From Mars to Aldebaran


   Following a close encounter (conjunction) on September 5th-6th with the ‘Red Planet’ Mars our Moon will orbit eastward waning toward last quarter phase on September 9th. On the 9th the Moon will have a not as close encounter with another red celestial object. This being the reddish star Aldebaran, the ‘angry eye’ of Taurus the Bull.
   Aldebaran is at one of the open ends of the v-shaped open star cluster, the Hyades, the shape making up the Bull’s face.

   You can follow the Moon’s changing daily position with the graphic sequence below.
   
   
   
   
   
   
   
   


   
   
   

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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September Apogee Moon

   Our Moon reaches apogee, (furthest from Earth), for this orbit, on Sunday September 6th. For this apogee the 19-day old waning gibbous Moon will be at a distance of 31.79 Earth diameters, 252,031 miles (405,606 km) from the Earth.

   On the date of the apogee the 19-day old waning gibbous Moon will be about 5o to the east from the planet Mars and both very visible through the night hours. Not visible to the naked-eye because of the bright Moonshine is the outer planet Uranus with a 5.8 apparent magnitude about 2-3o from the Moon.

   Does our Moon actually go around the Earth as this graphic shows? 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)

   
   
   
   
   
   
   
   
   

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


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Moon-Mars Conjunction

   Saturday evening September 5th watch for the 18-day old waning gibbous Moon to be very close, about 0.5-1o, from the planet Mars. Both objects are bright with Mars having a -1.93 apparent magnitude compared with the Moon’s much brighter -12.0 apparent magnitude.
   For another apparent magnitude comparison look west for the planets Jupiter (-2.52) and Saturn (0.33).

   The two, Mars and the Moon, should make for a striking combination with binoculars or low-power telescope eyepiece.

   
   
   

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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Moon – Jupiter/Saturn Conjunctions

   Friday and Saturday evening August 28th and 29th the 9 to 10-day old waxing gibbous Moon will be passing by the outer planets Jupiter and Saturn. On Friday evening the Moon will be about 1-2o from Jupiter and by the same time Saturday evening the Moon will be about 6-7o from Saturn. On either of the evenings the Moon and a planet will fit within the field of view of binoculars.

   
   
   

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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