Duck! Said Scorpius to Sagittarius

   Over the next several mornings, before the Sun rises, the Moon, as it wanes from gibbous to last quarter phase, glides past the stars of Scorpius the Scorpion and Sagittarius the Archer and the ringed planet Saturn.
   Apparently Archery is so loud that Sagittarius didn’t hear the warning and gets a face full of the Moon on the 21st.
   In the background is the Milky Way, but for the most part it will be difficult to see due to the bright reflected light from the Moon.
   Off to the west is Jupiter and Spica. Jupiter has been in retrograde motion since last month and is gradually moving west away from Spica.
   
   
   
   
   
   
   In the background is the Milky Way, but for the most part it will be difficult to see due to the bright reflected light from the Moon.

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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.

March Moon at Apogee

 Our Moon reaches apogee, (greatest distance from Earth), on Saturday March 18th. At that time the Moon will more or less be at a distance of 31.72 Earth diameters (404,640 km or 251,432 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*

*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?”

   On the morning of the apogee Moon the 20-day old waning gibbous Moon rises a couple of hours before the Sun and is visible over the southern horizon.

   
   
   

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.

Saturn at Western Quadrature

saturn-west-quadrature   Friday March 17th, the position of the planet Saturn with respect to the Earth and the Sun places this ringed planet at what is called western quadrature. Saturn is at a 90 degree angle from us as this graphic shows. Think third quarter Moon as that is a fair comparison of the relative positions. At this position Saturn leads the Sun across the sky from east to west as the Earth is rotating, meaning that Saturn rises before the Sun and also sets before the Sun.

   Saturn currently is within the constellation of Sagittarius the Archer as this graphic shows. From the northern hemisphere, looking toward the southern horizon, you can find Saturn to the east, left, from the reddish star Antares. Saturn shines with an apparent magnitude of around 0.5 compared with the 1st magnitude Antares.

Learn a little (or a lot) about Saturn by visiting the Cassini at Saturn mission web site.
Click here to go to the Cassini Mission web site.

   This is a short 5 minute video I made as part of a live musical performance called “Orbit”. This is a piece from the much longer tour of the solar system performance and video and shows Saturn and some of its moons as viewed from the Cassini spacecraft that month.

   
   
   


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 and Saturn Conjunction


   Tuesday morning February 21st the 23.5-day old waning crescent Moon will be 4-5o away from the planet Saturn as this graphic shows. With 7×50 binoculars the two should make for a striking pair.

   
   
   

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.

The Moon, Jupiter, and Spica – Together Again


   Wednesday February 15th the 18-day old waning gibbous Moon will be within a few degrees from the planet Jupiter and the blue-white star Spica in Virgo the Harvest Maiden as they rise in the east a few hours before sunrise local time.
   All three will fit within the field of view of a pair of 7×50 binoculars 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.

Moon Skips Past Stars and Planets

   Over the next several mornings, January 23rd to 25th the waning crescent Moon will pass by the star Antares, and the planets Saturn, and Mercury as these animated graphics are showing.

   
   
   

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.

Saturn at Solar Conjunction: 2016

10dec-saturn-solar-conjunction   Saturday December 10th the planet Saturn will have reached the astronomical coordinates that officially place it at solar conjunction. From our perspective the planet is behind the Sun, or on the opposite side of the Sun from the Earth.
   In reality it is not as much as Saturn moving behind the Sun as it is the Sun passing in front of Saturn – or so it seems. As a distant outer planet Saturn moves more slowly around the Sun than the Earth does. One year on Saturn is equal to 29.7 years (10,832 days) on Earth. So in one day Saturn would travel how much of the 360o orbit around the Sun? That would amount to approximately 0.033o each day.
   The Sun, in its apparent motion along the ecliptic moves at the rate the Earth is moving which is 0.99o each day. So with the Sun’s apparent motion (0.99o/day) it quickly, relative to Saturn, passes Saturn while both are moving eastward. So with that in mind you could start watching for Saturn to reappear in the morning skies later next month.

   
   
   

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.