Spring’s Vague Dim Sky

The spring night skies are noted for their huge blank and vague, dim areas.  That’s because we are looking right out into space away from our own Milky Way Galaxy.  The stars outside our galaxy are far away and small and faint.  the galaxy is like a huge plate that is actually visible only slightly all around the horizon line and below and invisible to us under our feet.  It does tip up from the east as the night progresses and more comes into view.  Most of the year we look through it at our closest neighbors who live in the Milky Way Galaxy with us.   There are wonderful exceptions to this dim darkness and that makes this actually quite an exciting opportunity to look.  We’re not so overwhelmed with billions of stars and the brighter ones show up with little competition.

Our main companions are easy to see.  The very bright Arcturus is high in the east in May and overhead in June.  You can find him by following the arch of the Big Dipper’s handle high in the northern sky.   Sight away from the dipper along the handle as it goes almost over head to the bright star, Arcturus.  Arcturus is in Bootes, the Shepherd, the rest of him is a bit vague but very kite like.  Arcturus is at the bottom of the kite where you’d tie on the tail.  [See the illustration.]

Keeping on the theme of dimness is Leo the Lion, note a backwards question mark with regulus below as the point, this time very well highlighted by Saturn right next to it in May and pulls away from it in June as the constellation moves decidedly west, soon to set.

Fitting our dim theme also is Cancer which is very subtle until it is highlighted for you by Mars in May.  In May the moon shares a binocular field with Mars.  Cancer is a dim blast of millions of stars in a tight and beautiful slow motion  explosion.   With clear skies you can see it with you own eyes too.  In June Mars moves away east towards Regulus and Leo.

A few days later is the solstice, June 20th.  Called the longest day of the year.  Actually June 14th is the earliest sunrise 4:31 A.M. The latest sunset is June 27th at 7:33 P.M. at 40º Latitude.   There’s a hourglass diagram that’s used to create what we call the longest day this year it’s the 20th.   The \”moment\” the sun is highest and hottest.  So why does summer continue to warm even as the sun spends less time in the sky and gets lower?  It’s counter intuitive!   Just found this explanation:  It takes a long time for that heat build up to dissipate.  So I guess the heat still produced plus the residue heat that lingers creates all that temperature rise.  Is this intuitive enough?  I leave it to you.

To close the circle [of the milky way galaxy] by June’s end Deneb, in Cygnus, the swan, is up in the east with the band of the our galaxy, the Milky Way, rising enough to be seen along the eastern horizon.  Vega, in Lyra, is even higher and these are two of the three stars of the summer triangle yet to show up.  The third star is Altar in Aguila, the eagle.

Ah… summer.  Welcome, been really ready for your arrival this year.

May/June ’08