We look back in time every time we look at the stars. In truth, we look back in time every time we open our eyes. It takes the light time to reach your eyes, so what you see may be an image from a billionth of a second ago, to thousands of light years away.
It may of interest to spot the relatively nearby stars and consider what you are seeing in relation to stages in your life, or that of your parents or grandparents — or ancestors.
The next time you have a birthday in the family, even your own, you might enjoy pointing out stars that in terms of light years, are within the time frame of the birthday celebrant’s own life.
Light travels at 186,282 miles a second in a vacuum. The distance light travels in a year is called a light year and is roughly 5.8 TRILLION miles.
Most stars of course, just within the Milky Way Galaxy, are many thousands of light years away.
The closest star of course, is the Sun, and it is eight light MINUTES away — if you see the sun shining eight minutes after your baby is born, that sunlight left the Sun the same time your baby came into the world!
There are no stars only one light year away, so there is no star to mark your baby’s first birthday!
The nearest star to the Sun is Proxima Centauri, about 4.24 light years distant. Proxima is a dim red dwarf star, requiring a small telescope to see. Proxima is loosely bund gravitationally to the slightly further (4.38), very bright double star, Alpha Centauri. Unfortunately you need to take your 4-year old toddler to southern Florida to barely glimpse this star system (the Tropics and below the equator are far better)!
Is your teenager 16 and learning to drive?
The bright star Altair is 16.7 light years away.
There are an estimated 52 star systems within a radius of 16.3 light years (the same as 5 parsecs, another unit of distance astronomers use).
These systems total about 72 stars, 64 of what are dwarf stars. One nine of these 72 stars exceed magnitude +6.5, which is generally the limit of naked eye visibility in a dark, rural location.
Only three of them other than the Sun are first magnitude of brighter, Alpha Centauri, Sirius and Procyon. The last two are placed in the Northern Hemisphere’s winter evening sky.
Most nearby stars, despite their relative closeness, require a small telescope to find.
Here’s the distance in light years of a few bright stars well seen in spring time evenings with just your eyes:
These are beyond anyone’s lifetime:
The North Star, Polaris, is 433.8 light years away.
How about the seven stars making up the Big Dipper? Starting at the tip of the handle is Alkaid, 101; Mizar, 78; Aloith, 81; Megrez (the star where the "handle" meets the bowl), 81; Phecda (bottom of the bowl), 84; Merak, 79 and Dubhe (the star at the front tip of the bowl), 124. Most are no further away than one’s average life span.
Within 50 lights years, there are about 133 stars which may be seen without a telescope.
The Moon, which reaches last quarter on June 6, is 1.3 light SECONDS away.
These stars are so very far away- yet we can see them. Imagine the power they put out!
Keep looking up!
— Peter Becker is Managing Editor at The News Eagle in Hawley, PA. Notes are welcome at firstname.lastname@example.org. Please mention in what newspaper or web site you read this column.