Why are we now starved of planetary activity in the after-sunset sky? There is an apparent busy-ness in the calendar, the Moon passing Mercury and Venus, even leading to a “trio” on April 12 of Moon, Venus, and the Pleiades within a circle of less than 3°. But all this is almost behind the Sun. Venus, around on the far side of its orbit, is moving slowly out into the evening sky, and May 5 will the very soonest when it will just possibly prick the just-after-sunset horizon, for us at mid-northern latitudes.
See the end note about enlarging illustrations.
Don’t expect to see any of the features in this picture, except possibly Mars, less possibly Mercury.
Here is the configuration of the planets in April.
This space view is from a viewpoint 5 astronomical units (Sun-Earth distances) away from the Sun, 15° north of the ecliptic plane, at ecliptic longitude 150°. The dashed line from the Sun, 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 from April 1 to May 1; and in yellow are sightlines to them from Earth at April 10.
So you can see that Mars is well out eastward in the evening sky, Jupiter and Saturn out westward on the morning side; but Mercury and Venus are in the Sun’s glare, the more distant part of it. Perhaps we can divide Sun-glare not only into its evening and morning halves but its near and far regions: the fore-glare and the yond-glare.
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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.
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I never thought of glare as being spherical. As such, it would take longer for Venus to appear to the eye when coming around behind the sun because it has to pass through the yond glare and fore glare., but would be visible closer to the sun as it approaches inferior conjunction if its reflected light only has to pass through the fore glare.
Yes, that could have been yet another diagram in my Venus book: a plan view from the north, showing the number of days Venus is in the yond glare (defined as say 15 degrees radius from the sun) and in the fore glare.
Superb “wan” that one, Kenneth Heisler!
With regard to the paucity of planetary activity this month you could say,
“Wan, that April …”
[apologies to Geoffrey Chaucer]