May Moon at Apogee

   Our Moon reaches apogee, (greatest distance from Earth), for this orbit, on Monday 18th. At that time the 26.5-day old waning crescent Moon will be at a distance of 31.88 Earth diameters 252,028 miles (405,600 km) from the Earth.

   On the day of the apogee the thin waning crescent Moon rises about 1-2 hours before sunrise local time. Looking carefully with binoculars you may be able to see nearby 4th magnitude star 20 Ceti, one of the many stars that are part of the constellation Cetus the Whale.

   

   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)

   
   
   
   
   
   
   
   
   

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.

Mars – Jupiter at Heliocentric Conjunction

   Saturday May 16th the outer planets Mars and Jupiter will reach a point in their respective orbit that has them at nearly the same heliocentric coordinates. This a system of tracking the planets as they make their 360o orbit around the Sun. Each Sun orbiting object’s orbital position is measured using degrees, minutes, and seconds of heliocentric longitude. Each object orbits the Sun at a daily rate determined by dividing 360o by the number of days an object takes to complete one orbit around the Sun.
   As the above graphic shows the two planets are arranged in a straight line out from the Sun. The Earth is not part of the line-up. This is a heliocentric view of their orbital positions with the Sun at the Center. A heliocntric longitude based view is not the same as a view from the surface of the Earth where there is a distinctly different view of the two planets.


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 Mars Conjunction x2

   Thursday morning May 14th the last quarter Moon will be about 8-9o to the west from the ‘Red Planet’ Mars. The following morning, Friday May 15th the waning crescent Moon will be about 6-7o from Mars but this time on the east side.



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-Jupiter-Saturn Conjunction

   Tuesday morning May 12th, before sunrise, the 19-day old waning gibbous Moon will be within a few degrees from the outer planets Jupiter and Saturn. All three will 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.


Also Follow me and other great resources at Feedspot.

Saturn Goes Retro!

   All Sun orbiting objects further from the Sun than the Earth will have orbital speeds slower than the Earth’s orbital speed. From our perspective on Earth orbital directions are toward the east.
   There will come a time when the faster moving Earth will overtake a slower mover and pass by that object much like a car passes a slower moving car on the highway.
   During the time that Earth is passing by an outer object there is an appearance that the outer object slows down and then orbits in the reverse direction, toward the west.
   This is known as retrograde motion. After a few weeks to a few months, depending on the outer object, the apparent westward motion slows to a stop and then the outer object resumes its regular motion toward the east known as prograde motion.
   Such is the situation for outer ringed planet Saturn. It begins retrograde motion this month and will resume its regular eastward, prograde, motion during September.

   Take a short tour of Saturn and some of its moons in this video clip from the longer Orbits video. These were part of a live performance by the group Dark Matter.

   
   
   

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 – Antares Conjunction

   Saturday morning May 9th the 16-day old waning gibbous Moon will be about 6-7o from the heart of Scorpius the Scorpion, the reddish star Antares.
   Joining the waning gibbous Moon will be the several of the visible planets arranged west to east starting with Jupiter, then Saturn, and Mars further east. The Dwarf Planet Ceres is also part of the planet spread but at 8th magnitude Ceres would require binoculars to see.

   
   
   
   

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.

Saturn at Western Quadrature – 2020

saturn-west-quadrature   Tuesday April 21st, 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 over the southeastern horizon about midway between Mars to the east, left, and Jupiter to the west, right.

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.