Saturn, You Are So Far Away!

click on graphic to see it larger
   Tuesday April 16th the outer ringed planet will be aphelion, its furthest distance from the Sun for this particular orbit. At aphelion Saturn will be approximately 10.0657 AU (1,505,807,287 km; 935,665,269 miles) from the Sun. Sort of splitting the difference Saturn is approximately 9.722 AU (1,454,390,499 km; 903,716,358 miles) from the Earth.
   Saturn is visible over the southern horizon before sunrise local time. It is near the ‘red planet’ Mars to the east, and Saturn is east from the heart of Scorpius the Scorpion, the reddish star Antares, and even further to the west is another outer ringed planet, 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.

April Moon at Descending


   Tuesday April 10th the thin waning crescent 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 24-day old waning crescent Moon will be over the eastern horizon about an hour before the Sun rises.

   
   
   

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.

April Apogee Moon

April Apogee Moon   Our Moon reaches apogee, (greatest distance from Earth), on Monday April 8 th. At that time the Moon will more or less be at a distance of 31.68 Earth diameters (404,144 km or 251,123 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 22-day old last quarter Moon will be over the eastern horizon at around sunrise local time and within about 11o from the ringed planet Saturn, and about 8-o from Mars.

*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.

A Week of Moon Conjunctions


   Over the next 7 days (mornings) the Moon, as it wanes toward last quarter, will pass closely by several planets and brights stars in some close and some not so close conjunctions.
   Perhaps the best morning will be on April 7th when the near last quarter Moon will be 1-2o from Saturn and about 4o from Mars.
All three will easily 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.

Mars and Saturn Conjunction


   Monday morning April 2nd the planets Mars and Saturn will be separated by about 1-2o as they both rise in the east. Both planets are near the Milky Way and within the boundaries of the constellation Sagittarius the Archer.

   
   
   

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.

Mercury at Inferior Conjunction

orbital-positions   Sunday April 1nd 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.

Waning Gibbous Moon Near Spica


   Sunday evening April 1st the waning gibbous Moon will be within about 6o from the blue-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.