Friday, May 20, 2016

A Curious Celestial Configuration - By Contributing Astronomy Editor, Dan Matlaga



Welcoming Back Professor Dan 

With some timely information regarding the night sky TOMORROW NIGHT!  

Read on:


If at 10:30 p.m.your southeastern sky is clear the night of Saturday, May 21st you can see a curious meeting of four objects forming a square close to the horizon.  Figure 01 illustrates the view. 


ENLARGED THE PICTURE AS MUCH AS POSSIBLE, STILL A LITTLE TRICKY TO SEE THE NAMES.
THEY ARE (LEFT TO RIGHT, TOP 2): THE MOON AND MARS AND (LEFT TO RIGHT, BOTTOM 2):  SATURN & ANTARES

The four objects are the Moon, Mars, Saturn and the bright star Antares. The field of view in Fig. 01 is sufficiently large to include the South and East cardinal point designations, this to signify the scale of the quadrangle.



The moon is the brightest object of the four; the brightest because it is near. The moon reflects only 7% of the sunlight that strikes its surface.  It is really a poor reflector.  The Earth reflects 30%, Mars 29%, and Saturn 47%. The Moon, a quarter the size of the Earth, is but a quarter million miles from the Earth.  That is, a beam of sunlight reflected off the moon’s surface will take but 1.3 seconds to reach your eye.





One month out of 24, Mars, half the size of the Earth, is opposite the sun in our sky and is said to be “in opposition.”  In the present cycle, Mars will be in exact opposition May 22nd, just one day after this night’s observation. As you view Mars, the light that strikes your eye left Mars 4.25 minutes ago.



Saturn is the sixth planet from the Sun.  Nine and a half earths would have to be lined up to equal the diameter of Saturn. The light from the planet Saturn takes 1.25 hours to reach the Earth.  




Note where Saturn is on May 21st.  Come back 29.6 years later. During that time Saturn would have appeared in front of each 12 zodiacal constellations. In 29.6 years it will be back in the same position you see it on May 21st. Where will you be 30 years from now?






Mars looks like a red star, Antares is a red star. It is one of the largest stars visible to the naked eye. If Antares were the size of a baseball, our nearly one million mile diameter Sun would be scaled to smaller than the period at the end of this sentence.  Antares “surface” temperature is about 5,700 degrees.  The Sun’s surface temperature is 10,000 degrees.  How can Antares be so bright at a distance of 600 light years and so cool? Place Antares where the Sun is and the planets Mercury, Venus, Earth and Mars would orbit inside the star.  There are many square miles of surface area on Antares pumping out the red light. Antares is in fact 11,000 times brighter than the sun.


The word “Antares,” comes from the Greek.  It translates as: “the enemy of Mars.” Ares was the Greek word for Mars, while the prefix “An” can loosely be translated as “Anti.”  The idea was every two years Mars and Antares ride the sky together. The tension was… “which of the two will be the brighter red?”  You can judge for yourself who wins this time.  Or, to be honest, you can wait a few nights when the bright Moon’s light is no longer part of the picture. 

Thanks Dan!  I, for one, will be sure to check all of this out tomorrow night and I'm sure all of our Kabrini Message astronomy buffs (and there are many!) will, too.