Expert: Tom Whiting - 6/3/2010

Question
Dear Tom,
I read your bio after a few questions you answered seemed to deal very closely with a Science Project I am doing research for. I am from Connecticut and I am looking for stars to use in an NELM evaluation of Night Skys in New England. My original idea was using the Big Dipper and the Milky Way, but I could not find a reliable source of the magnitudes of some of these stars. I was hoping you could help me answer some of these questions or atleast point me in the right general direction.

Thank You,
Dan

Answer
Hi Dan,
The Big Dipper stars range from magnitude 1.8 to 3.3 and are given at
http://www.brighthub.com/science/space/articles/23584.aspx
along with their distances from the Solar System.

The Milky Way is composed of thousands of naked eye stars, ranging from bright zero magnitude
(Capella, Rigel, and Vega) down to the naked eye limit of 6 to 7, depending on a person's age and vision. Generally, younger eyes can see dimmer stars, so you'll have to name specific stars for a specific magnitude number.  Generally if you Google a star name, it will give you the magnitude of a specific star.  And realize that many stars are slightly variable in brightness too, so it depends on how many significant figures you want to go out to.

Remember magnitude is a reverse scale, the lower the number the brighter the object, and it's also a logarithmic scale too; one whole number change is 2.5 times brighter (or dimmer), 2 whole number changes is 2.5 squared or 6.25 brighter, 2.5 cubed for 3, 2.5 to the 4th power for four, and 5 whole number magnitude changes is about 100 times change in brightness. So it's an exponential scale, NOT arithemetic... like 2.5, 5, 7.5, 10, 12.5, etc.
It really goes 2.5, 6.25, ~ 16, ~ 40, 100, 250, 625, 1600, 4000, 10,000, etc.  change in brightness for each whole number change in magnitude.
Clear Skies,
Tom Whiting
Erie, PA