1st quarter Moon: visible during afternoon

Event Date: January 18th

Time: 3:46 PM

Brief

   It is always a pleasure to see the Moon in the sky, regardless of what time of day or night.  However, it may not be often that we are viewing it at exactly 1st or 3rd quarter.  Many people look up the time of when it is full; especially when above the horizon at such time.  However, when highest above the horizon during official 1st quarter, it is often seen that way before dark; depending on far north it is of the Sun, seen from the northern hemisphere.  Below, I will show it at 1st quarter time, displayed on the top right corner.  All of North America will have it well placed when this happens, as the Sun is in the part of the sky as well in mid-April, slightly further north of the ecliptic as well.  The orbit shows the Moon's latitude north of the ecliptic in image one, while image two shows a 1º field-of-view zoom-in.  

click on images to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp.

Detailed

   For the zoom-in, the Moon is magnified about 50x, which is ideal for viewing our satellite's entire disc-shape.  Notice of course, how straight the terminator is, as opposed to curved, in the case of a crescent or gibbous.  On that note, the curve comes back, starting immediately after 1st quarter, although it will be very gradual and not noticeable with optical aid until several hours later.  Although the Moon's illumination-increase rate is at or near its fastest at the time of 1st quarter, it still isn't too obvious with the eye alone at first glance.  Monitor it every day as the Moon "fattens" further to full next week.  Also, since first quarter happens only 91 minutes before official Sunset time, enjoy the Moon at transit still looking very much half-lit.  With the eye alone, when looking right at the time of Sunset, clarity of the terminator may be sharp enough to see the shadowing.  Because of this, the Moon may also looks slightly than half illuminated with the eye, which is normal.  If waiting later until nautical or astronomical twilight, the reflection of Sunlight makes the terminator more difficult than with the eye alone.