FirstLight Astronomy Club

33°29.6'N / 117°06.8'W / 1190 ft.

The Perfect Speed of Light

We take the instantaneous world around us for granted, to be sure. As we sit or walk or drive or fly, our environment seems to be there with us step by step; there is no apparent lag between the time some nearby event actually occurs and the moment it gets to our eyes.

That is due to the fantastic speed of light. Traveling at over 186,000 miles a second, the light bouncing off your kids or that car or yon bird gets to your eyes so tremendously quickly that we are essentially seeing those events instantaneously.

Imagine, though, a world where light was much slower. Imagine that light travelled only a couple yards per second instead of thousands of miles. It would be a world of mass confusion. You could turn on a light and only gradually would the room come into the view in a wave of illumination. Your spouse could get up to go to the kitchen and you wouldn’t even see him get up until he was already over opening the refrigerator. Imagine the mess driving would be with slow light!

Just about anything involving movement would be such a warp of visual confusion that life as we know it would simply end. Your entire waking life would be a nightmare of delay.

Now this is never going to happen. My immediate point is that the superfast speed of light makes it seem like everything around us is true and precise, and that makes life very comfortable.

But though we are thankful for that great speed, astronomers are glad it doesn’t go faster.

If the speed of light were really instantaneous, astronomy would not have that great opportunity to see the past as it happens. Bear with me here...

Since light does have a speed limit, it does take some time for it to reach us. But it isn’t until we cough up big distances that we even notice.

The moon is far enough away that it takes light over a second to get here. Thus, we see it as it was a second ago. The sun is far enough away that it takes its light over 8 minutes to get here. Therefore, we see the sun as it used to look, over 8 minutes ago.

Go way far away, to the nearest other big galaxy, Andromeda, and we see it as it “was” over 2 million years ago. With the best telescopes, we can see well over 10 billion years ago into the past and every era in between. Studying that past, right up to the present - by watching it actually happen - helps us figure out how the Whole Show proceeded from Act I until now.

The speed of light is fast enough for a wonderful life here, but slow enough to let us watch the history of the entire creation.

Little February

Once upon a time, over 2700 years ago, our calendar here in “The West” had a mere ten months to it. It began in March and ended in December. There were no winter months - no January, no February. The calendar lasted just over 300 days with those extra 60 dateless winter days tagged onto the end.

So where did little February come from?

The history of the Roman calendar, the calendar from which we derive our own, is a complete mess of a story, mainly due to the extremely uncooperative natures of the sun, moon, and stars; their varying movements do not make things nice and neat. The calendar you have hanging on your wall is squeaky clean compared to what Rome first had. Ours is the end result of literally centuries of reform. Here we will focus on one small aspect of those reforms, the genesis of tiny February.

The year use to start in March - a month named for the god Mars - because that is when spring began. That the calendar year used to begin then is still reflected in our names of the latter months such as October, where “oct-” means eighth, or December, where “dec-” means tenth. Back then they really were the eight and tenth months.

It wasn’t until around 700 B.C., when the second king of Rome, Numa Pompilius, sat on the throne, that things changed. Pompilius plopped an extra 50 days into the calendar and two new months to fill them, specifically January and February.

It was sometime between Numa’s time and the time of the decemviri - a ruling group of ten Roman men back in the 5th century B.C. - that January and February got promoted to the first two months of the year.

January was named for the Roman god of the doorway, the two-faced Janus. We still see his name in our word “janitor” which long ago meant doorkeeper, but evolved into the more custodial meaning we have today.

February was not named for a god like March was, nor for a number like October, nor for a caesar, like July and August were. It was named for a specific rite that happened right before springtime called Februa. This very old ritual had been observed since ancient days to purify a village or city of nasty spirits. It was like a superstitious spring cleaning.

Maybe we can all take a little lesson from little February and start some cleaning up in our own lives this month. I sure could.

Until next month, clear skies!
Temecula Valley High School / Temecula, CA · Some images © Gemini Observatory/AURA Contact Me