[morning] Summer Triangle shown with grids

Event Date: February 10th

Time: 6:30 AM

Brief

I glazed over the Summer Triangle topic a few days ago, when I was showing pointer stars for the Hercules Star cluster mentioned here.  Now that a little more calendar time has passed, we can come back to Vega, Deneb and Altair, making up the "star points" of the popular asterism.  Vega has been above the horizon for close to six hours, as viewed from this latitude of almost 38º N; it is 56º in altitude at the time above.  Deneb rises about 70 minutes later, and least-north Altair rises a little over 2 hours after Altair.  Of course at different latitudes, these rise-gaps will be different.  Let's look at the triangle here:

Detailed

   Over the next couple of months, we will see the triangle's stars east of the meridian.  As we get into spring, we will see it for more hours during the night.  Eventually by summer, we will see the triangle all night long, for a string of weeks; hence, its given name...or adjective, if you will!  Of course, the nights are shorter as we reach the June solstice, so this is why we will see them above the horizon and dawn and dusk.  Vega and Deneb get very high in the sky, and we will observe them this way.  Altair as mentioned, is about 30º closer to the celestial equator and therefore, spending less hours above the horizon.

   Shown below as a reminder, is the celestial grid and equator. Rounded, Vega is at 38º, Deneb 45º, and Altair 9º.  I also am showing the azimuth meridian, since I mentioned it at the beginning of this section.  To show it more clearly, I moved the screen down.

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