Mercury at Inferior Conjunction

orbital-positions   Wednesday December 13th the innermost planet Mercury reaches inferior conjunction. At inferior conjunction Mercury will move between the Earth and the Sun – much like the position of the Moon at new phase. The graphic to the right shows the planet positions relative to the Earth and Sun for both inner planets and outer planets.

   While at this inferior conjunction Mercury will not be directly in line with the Earth and the Sun – on the ecliptic. Mercury has an orbital inclination of 7o with respect to the ecliptic. So like our Moon, Mercury during each complete orbit, will cross the plane of the ecliptic moving north (ascending node) and also moving south (descending node). For this inferior conjunction Mercury will be north of 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.

Taurus Sniffs the Moon!

   Saturday evening November 2nd the 14.5-day old waxing gibbous Moon (full Moon tomorrow) will be a couple of degrees from the reddish star Aldebaran in Taurus the Bull. Aldebaran is at one end of a v-shaped open star cluster, the Hyades, that makes up the face of Taurus. Because of its reddish color it has been described as the angry eye of the bull.
   Normally the Hyades are a great view with binoculars as is the Pleiades, another open star cluster that is often described as a ‘baby dipper’.

   
   
   

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.

Mars – Spica Conjunction


   Starting with Wednesday November 27th and continuing for the next several days the ‘Red Planet’ Mars will pass within about 3-4o from the blue-white star Spica in Virgo the Harvest Maiden. This animated graphic is set for 5:30 am CST at 1-day intervals starting with November 27th and ending on December 3rd.
   Jupiter is several degrees further east from Mars but by this time of the morning Jupiter will have just risen.

   Those familiar with the starry sky probably have heard the mnemonic “Follow the Arc to Arcturus, then speed to Spica” as a way to use the stars forming the curved handle (the ‘Arc’) of the Big Dipper as a guide to the reddish star Arcturus and then Spica. Read a bit more about following the arc from a previous post.
   
   
   

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.

November Moon at Apogee

   Our Moon reaches apogee, (greatest distance from Earth), on Tuesday November 21st. At that time the Moon will more or less be at a distance of 31.84 Earth diameters (406,132 km or 252,359 miles) from the Earth.

   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*

   On the day of the apogee the 3.5-day old waxing crescent Moon will be over the southwestern horizon at sunset local time. Were it not so bright the glow of the Milky Way in the background might have been visible. Saturn is visible, but it is low above the horizon.

*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.

Waxing Crescent Moon Conjunctions with Mercury and Saturn

   Over the next two evenings, November 19th and 20th the waxing crescent Moon will be passing by the innermost planet Mercury and then one of the outer planets, Saturn. The thin 1.5-day old waxing crescent Moon will be near Mercury on Sunday the 19th, and then the 2.5-day old thin waxing crescent Moon will be near Saturn on Monday the 20th.

   
   
   

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.

Moon Splits the Distance


   Wednesday morning November 15th the thin 27-day waning crescent Moon will be located more or less between the planet Mars and the bluish-white star Spica in Virgo the Harvest Maiden.

   
   
   

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.

Moon Conjunction with Mars and Spica


   Tuesday morning November 14th the waning crescent Moon will be within a few degrees from the ‘Red Planet’ Mars and the bluish-white star Spica in Virgo the Harvest Maiden. Then as this animated graphic illustrates the waning crescent Moon will pass by Jupiter and then Venus over the next few days.

   
   
   

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.