Summer Triangle lower each evening

Event Date: January 2nd

Time: 5:30 PM

Brief

   Yesterday, I showed the Summer Triangle stars in the morning sky.  Whether rising or setting, the Sun is far enough south of the northern stars, that it isn't in the way to cause too much glare.  Also, with the early Sunsets at this time of year, it gives us alot of darkness and therefore, more hours to see the Triangle after Sunset and before Sunrise.  However, now that we are past the winter solstice for our hemisphere, we will lose--on average--about a minute of darkness per day; this starts slowly this week and throughout most of January.  Here are the three stars, forming the triangle.

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

Detailed

As we get close to the March equinox, the longer days and slightly longer twilight periods each day between now and the solstice will lead to all three stars of the triangle becoming too low to view come darkness, with Deneb being the last; following Altair and then Vega.  All three stars are high enough to view this evening, although as mentioned yesterday, they will dip one by one below the horizon.  In comparison to least-north Altair, Vega and Deneb are high enough south that they will be up longer.  

   Unfortunately for big evening [viewing] Summer Triangle fans, our revolution around the Sun is causing them to rise and set almost four minutes earlier each day.  This means that by the time they are visible even a couple of weeks from now with dark enough skies, they will not seem quite as bright; their light will be refracted through the atmospheric pollution.  Also, any obstruction such as tall houses or trees will hinder viewing.  Try viewing somewhere where the horizon is clear, such as a hilltop looking towards the a flat plane or large body of water (i.e. even an ocean), where there is no land horizon to get in the way of the view.

   Finally, If house and tree obstruction are not blocking the view, enjoy their colors through atmospheric pollution, as their light refracts; a rainbow-y range of colors for brighter Vega, and a predominantly green color for dimmer Deneb.