Mercury at Western Elongation

   On Friday August 9th Mercury, the innermost planet, will reach its orbital position known as greatest western elongation at 19.0o. At that moment Mercury, the Sun, and the Earth, would be arranged in something close to approximating a right angle as this graphic shows. Even though it sounds confusing at western elongation for either Mercury or Venus the inner planet will be to the right of the Sun as we view them, meaning that at western elongation an inner planet rises in the east before the Sun rises. And at eastern elongation with the inner planet on the left side of the Sun the inner planet follows the Sun across the sky setting after the Sun sets.

   From our perspective the orbits of Mercury and Venus appear to move from one side of the Sun to the other – out to the left (east) from the Sun to eastern elongation, then reverse and move westward (inferior conjunction) between the Earth and the Sun to western elongation. From there the inner planet moves eastward going behind the Sun (superior conjunction) and eventually reappearing on the eastern side of the Sun for an eastern elongation. Repeat over and over – do not stop!

   Mercury is visible in the morning skies about an hour before sunrise local time, as this graphic shows.

   
   
   
   
   

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.


Also Follow me and other great resources at Feedspot.

Moon on the Move – Actually It Doesn’t Stop!

   Over the next couple of evenings the waxing gibbous Moon will pass by two outer planets, Jupiter and Dwarf Planet Ceres. On the 8th the 8-day old waxing gibbous Moon will be about 2o from the Dwarf Planet Ceres, and on the 9th the 9-day old Moon will be about 2o 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.


Also Follow me and other great resources at Feedspot.

Moon-Spica Conjunction

   Monday evening August 5th the 5-day old waxing crescent Moon will be within about 5-6o from the blue-white star Spica over the southwestern horizon. Both will set shortly before midnight local time.
   Spica is part of the constellation Virgo the Harvest Maiden and represents a bundle of grasses, perhaps wheat, in her left hand.

   
   
   

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.


Also Follow me and other great resources at Feedspot.

August Moon at Perigee

   Our Moon reaches perigee, (closest distance to Earth), for this orbit, on Friday August 2nd. At that time the Moon will be at a distance of 28.175 Earth diameters, 223,319 miles (359,398 km) from the Earth.

   On the day of the perigee Moon the 2-day old thin waxing crescent Moon will be over the western horizon setting about 1 hour after the Sun sets.

   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.


Also Follow me and other great resources at Feedspot.

A Black Moon

   What is a “Black Moon”? According to a commonly used definition a “Black Moon” is any month during which there are 2 new Moons, or even more rare a month with no new Moons. Obviously the Moon at new phase is in the direction of the Sun and therefore is not visible at all, perhaps given rise to the name “Black Moon” because the illuminated side of the Moon is toward the Sun, and the unilluminated, dark, side of the Moon is toward the Earth.
   On Thursday August 1st the first of two new Moons this month will rise about 30 minutes after the Sun rises and will not be visible as it follows the Sun across the sky to moonset about 1 hour after sunset local time. On August 30th the second new Moon of the month will follow a similar pattern as the new Moon on August 1st in that this new Moon also will not be visible as it too follows the Sun, setting within an hour after the Sun sets. Graphics below are set for the time when the new Moon transits, or is due south, and is mid-way between rising and setting.
   What makes the term “Black Moon”, in this instance, interesting is that depending on your time zone the “Black Moon” may have been either July or August depending on your local time zone for the new Moon of July 31st or August 1st.

 
New Moon Dates and Times (using UT)
July 2          19:16 UT
August 1         3:12 UT  (July 31 10:12 pm CDT)
August 30       10:37 UT


   
   
   

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.


Also Follow me and other great resources at Feedspot.

July Moon at 2nd Ascending Node

   Tuesday July 30th the 27.5-day old thin waning crescent Moon will be crossing the plane of the ecliptic moving north relative to the ecliptic. 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 day of the node crossing the very thin waning crescent Moon rises about an hour before the Sun rises and is located nearly directly west from the ‘Twin’ stars, Pollux and Castor.

   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)

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 return to bobs-spaces.


Also Follow me and other great resources at Feedspot.

A Bullish Moon, or A Moon – Bull Conjunction, or Bull Gets Mooned!

   Over the next 3 mornings, July 26, 27,and 28 before sunrise, the waning crescent Moon will be moving across the shoulders and head of the constellation Taurus the Bull. As it traverses the constellation pattern the waning Moon will come within about 8o from the open star cluster, the Pleiades and within about 4-5o from the v-shaped open star cluster the Hyades.
   This should make for some good viewing through binoculars, especially on the 27th when the Moon passes about 2-3o from the reddish star Aldebaran in the Hyades. How close the conjunction between the Moon and Aldebaran will be depends greatly on your viewing location’s longitude. This graphic is for when the two are their closest which is 2.5o around 1 UT (8 pm CDT).


   
   
   


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.


Also Follow me and other great resources at Feedspot.