March Moon at Descending Node

2jan-descending-node
   Saturday March 25th the -day old 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 thin 26.7-day old waning crescent Moon will be over the southeast horizon at sunrise local time.

   
   
   

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.

Venus at Inferior Conjunction

   Saturday March 25th the inner planet Venus reaches its orbital position known as inferior conjunction.
   This is one of four points along an inner planet orbit. At inferior conjunction Venus is between the Earth and the Sun – sort of like our new Moon phase – but not necessarily directly in line. If that were so, inferior conjunction at the same time as Venus in direct line with the Earth and Sun (a node crossing at inferior conjunction) it would be a somewhat rare transit of the Sun by Venus. These happen as a pair of transits about one time each century with the last pair of Venus transits in June 2004 and June 2012. Here are some pictures of the June 2012 Venus Transit. Here is a link to the Vimeo web site to watch a video of the 2012 Venus Transit.
   By the way the next pair of Venus Transits are December 2117, and December 2125.

    At this inferior conjunction Venus is north of the ecliptic heading south toward its descending node and ecliptic crossing 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.

Sun Not in Aries But it is The March 2017 Equinox

   Monday March 20th is an equinox day. This means that for those in the northern hemisphere winter is ending and spring has ‘sprung’ (starts). For our counterparts south of the equator summer is ending and fall is beginning. From a geographical perspective we would describe the Sun as being over the Earth’s equator, and as this graphic shows there would be an equal amount of daylight and night on our planet as a result.
    At mid-day on the equator the sun is directly overhead and from that latitude you have no shadow, just a ‘blob-like’ shadow at your feet as this picture of my feet taken at mid-day in Quito Ecuador shows.

    Regardless of your hemispheric preference get outside and cast a shadow!

  Northern hemisphere spring officially (well at least astronomically) begins at 10:29 UT on the 20th (05:29 am CDT) when the Sun reaches the celestial coordinates of 0 hours and 0 degrees as it moves northward along the ecliptic crossing the celestial equator. At this location the Sun is within the constellation of Pisces the Fishes and not just entering Aries the Ram as the pseudoscience of astrology would have you believe.

    To learn more about the celestial coordinates click here to read a previous post about seasons and the equinox.

   Click here to see the online world sunlight map used to make the day/night graphic at the top of the page.

sun-earth   Click here to go to the NASA Sun-Earth Days web site.

   Here is a short series of hourly pictures taken during the day on the September equinox on the equator in Quito Ecuador at Collegio Menor San Francisco de Quito, a private school that I visited and did the SunShIP project with (Sun Shadow Investigation Project).

This slideshow requires JavaScript.


   
   
   


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.

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.

This slideshow requires JavaScript.

   
   
   

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 Near Jupiter and Spica


   Tuesday evening March 14th look for the waning gibbous Moon to be about 5-6o from the giant planet Jupiter and the blue-white star Spica. Both of which are within the constellation of Virgo the Harvest Maiden. The trio will make for an interesting view with 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.