Explore the Universe - Alpha Capricorni

The weather has not been conducive to any meaningful astronomical observations from the backyard.  Therefore, the blog will continue with updates of observations made during the Fall of 2016.  Alpha Capricorni was observed on the first evening of October in 2016.  It is an optical double separated by 6.6'.

A note should be made about how the Bayer naming convention works for stars.  Basically, the brightest star in a constellation is given the name of the first letter of the Greek alphabet -- Alpha.  The second brightest star is the second letter of the Greek alphabet -- Beta.  This pattern continues down to Omega.  Then it continues using Latin letters. After the Greek letter, the genitive form of the constellation then follows.

For example the brightest star in the following constellations are named:

Taurus: Alpha Tauri (Aldebaran)
Ursa Minor: Alpha Ursae Minoris (Polaris, The North Star)

The genitive case in Latin is the possessive case familiar to English.  Alpha Orionis would be translated to English as Alpha of Orion.

There are a few confusing rules to the Bayer System.  The brightest star in Gemini is Beta Geminorum (Pollux) and the second brightest star is Alpha Geminorum (Castor).  When Johann Bayer developed the system in 1603 he noted some stars in the same constellation were of similar magnitude and labelled the first to rise as the Alpha.  This is the case with Gemini and Orion and many others.  It is wise to consult a star atlas to find the correct names of the stars you see in the sky.

Also if the stars happen to be an optical double, binary or a multiple star system, numbers are inserted between the Greek Letter and the genitive form of the constellation name.  A good example of this is shown in the Alpha Capricorni log below:

Alpha Capricorni Observation Record

A final note on the angular separation measurement I have been using. ° is the number of degrees, ' is the number of minutes (60' in 1°) and " is the number of seconds (60" in 1').  For example, depending on where Jupiter is in its orbit it can be between 30" and 51" across or you could say 0.5' to 0.85' across.

The weather is looking good for next week and hopefully we can all enjoy a relatively warm evening to soak in the light of the full moon.