Saturn ahoy!

On Monday morning, May 3, if you stand looking toward where the Sun is promising to rise, you will be on the bow of Ship Earth as it sails forward on the sea of the ecliptic, and ahead are two other craft: the Moon, sailing across our bow, and Saturn on a far more distant course.

See the end note about enlarging illustrations.

For the Moon will be at its Last Quarter phase, and Saturn at its phase called west quadrature.  Both expressions mean that they are 90 degrees to the “right” (west) of the Sun.

Don’t expect to see, in twilight, all the starry features included in the picture.  They are there to give a sense of where we are facing in the wider universe.

The west-quadrature moment is May 3 at 10 hours by Universal Time (5 or more hours earlier by American clocks), which is just about exactly the time of the picture.  And 10 hours later the Moon will pass closest to Saturn, and almost simultaneously reach its Last Quarter position.

You can see that the “Earth’s direction of travel” (tangent to our orbit and essentially 90° from the Sun) has almost reached Saturn, and the Moon is hurrying to reach it.

This space view is from 15° north of the ecliptic plane, and 5 astronomical units (Sun-Earth distances) away from the Sun.  The dashed line, with ram’s-horns “Aries” symbol, shows longitude 0°, the vernal equinox direction.  The Sun is exaggerated 4 times in size, the two giant planets 50 times, the four inner planets 300 times.  The planets’ paths are shown in April and May; in yellow is the sightline from Earth to Saturn at May 3.

Here is Saturn through the telescope, on May 1 and June 1.

The longer and shorter lines from the planet point to the equatorial and ecliptic north and south poles.

Around this time, Saturn casts the most noticeable shadow on its rings.  This situation will last through the month: Saturn is hovering at about the same place in the sky.  It will be at its stationary moment on May 23, and will again be near the Last Quarter Moon on May 31.

Anagram department

Moonstarer.

No prize for solving that one.  But see if you can devise an anagram involving “Saturn.”  I gave up.

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ILLUSTRATIONS in these posts are made with precision but have to be inserted in another format.  You may be able to enlarge them on your monitor.  One way: right-click, and choose “View image”, then enlarge.  Or choose “Copy image”, then put it on your desktop, then open it.  On an iPad or phone, use the finger gesture that enlarges (spreading with two fingers, or tapping and dragging with three fingers).  Other methods have been suggested, such as dragging the image to the desktop and opening it in other ways.

Sometimes I make improvements or corrections to a post after publishing  it.  If you click on the title, rather than on ‘Read more’, I think you are sure to see the latest version.

This weblog maintains its right to be about astronomy or anything under the sun.