May Moon at Descending Node

   Wednesday May 22nd the Moon will be crossing 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 day of the node crossing the 17.5-day old waning gibbous Moon will be 5-7o to the west from the ringed planet Saturn. The following day, May 23rd, the 18.5-day old waning gibbous Moon will have orbited to the east side of Saturn passing within 5-6o.


   
   
   
   
   

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The Moon and a Dwarf Planet

   Monday morning April 22nd, before the Sun rises, look toward the south-southwest for the 17-day old waning gibbous Moon. While the Moon is obviously easy to see at a -12.60 apparent magnitude, the nearby, (2-3o), dwarf planet Ceres with an apparent magnitude of 6.90 is outshined by the Moon and is not visible.
   As this graphic shows all of the naked-eye visible planets except Mars are arranged from west to east above the horizon. While not naked eye visible Neptune, with an apparent magnitude of 7.94, is also shown. This arrangement of planets then offers an opportunity to visualize the plane of the ecliptic, the Earth’s orbit extended onto the sky. The plane of the ecliptic is one of the primary frames of reference for our solar system, and one of the things the other 7 planets have in common is that their respective orbits are all within about 7o from the plane of the ecliptic. Even our Moon stays within about 6o from the ecliptic.
   
   
   

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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Twin Conjunctions

click on graphic to see it larger   Monday February 18th the inner planet Venus will be about 1o from the outer planet Saturn as both rise a couple of hours before the Sun rises. The two will make for an interesting view with binoculars.

   Also, on Monday February 18th the 14-day old waxing gibbous Moon will be about 7-8o to the west from the star Regulus in the constellation Leo the Lion. The following day, February 19th, the full Moon will be about the same distance from Regulus but now on the east side. Both rise in the late afternoon about 2 hours before the Sun sets.

   
   
   

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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Venus – Jupiter Conjunction

   Wednesday morning January 23rd the inner planet Venus and an outer planet, Jupiter, will be rising together a couple of hours before the Sun rises. The two planets will be about 2-3o from each other and will easily fit within the field of view of binoculars. The two planets have been moving toward this conjunction and as the days pass Venus will continue moving east and away from Jupiter.

   
   
   

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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November Moon at Perigee

   Our Moon reaches perigee, (closest distance to Earth), for this orbit on Monday November 26th. At that time the Moon will be at a distance of 28.74 Earth diameters 227,809 miles (366,623 km) from the Earth.

   The 18-day old Waning gibbous rises after sunset and is visible all night between the Gemini Twin stars and the bright star Capella in Canis Minor. Off to the east is the inner planet Venus shining brightly with an apparent magnitude of -4.6, and within about 4o from the blue-white star Spica (0.9 apparent magnitude) in Virgo the Harvest Maiden. About 10o east from Venus is the closest Dwarf Planet, Ceres. With an apparent magnitude of 8.0 Ceres is not visible to the unaided eye.

   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)

   Read this very informative article about the Earth-Moon system and their orbital motions, written by Joe Hanson. “Do We Orbit the Moon?”

   
   
   

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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Planet-A-Palooza plus the Moon

   This is one of those ‘best of times’ with regard to planet viewing. All of the visible planets are above the horizon although Mercury sets just before Mars rises. Times like this make it easy to visualize the ecliptic and its relationship with the planets. And our Moon, as it waxes toward full phase over the next several days, will pass by several planets and dwarf planets.

Click on a graphic to start a slide show.

   
   
   

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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A Planetary Line-Up, Plus the Moon

   For the next week or so the evening skies will be filled with planets and dwarf planets. With the right timing and a relatively flat horizon you might be able to see Venus just before it sets and Mars just after it rises. A caveat to this is that as each day passes Mars will rise earlier while Venus, each day, will be setting earlier. And with the exception of Ceres the dwarf planets are too dim to be seen with the naked eye.

   As this graphic shows, the planets are closer to the ecliptic than the dwarf planets due to differences in the respective inclinations. Inclination: Every object orbiting the Sun has an orbital path that is tilted or inclined from the Earth’s orbit – the ecliptic.

   The waxing gibbous Moon is roughly mid-way between the red star Antares in Scorpius the Scorpion and the planet Saturn.

   
   
   

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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