Well, that is simple enough;
it is 24 hours long, right? Well not
exactly, and depending if you are talking about a solar day or a stellar
day. The stellar day is the time it
takes the earth to rotate one time in respect to the celestial background and a
solar day is what we are most familiar with, when the sun reaches the same spot
in the sky for each earth rotation. 45
years ago, the second was defined in terms of the wave length of light and up
until recently when some neutrinos seemed to break the speed of light, that was
the most accurate (and still is) constant to base time on. So, I guess that means that the average
length of a day is 86400 seconds.
OK, everything seems to be
running smoothly but wait, there is always a catch somewhere. As far as the Earth is concerned it is the
Moon that is putting on the brakes. Because
of the Moon’s gravity, it has slowed the rotation of earth down a bit. Did you know awhile back the length of a day
was more than two hours less than it is now.
Let’s see, 2 hours times 365 days equals 730 hours divided by 24 equals
30.42 days. That means we have to live
about a month longer each year to be the same age as you would have been if you
lived back 620 million years ago!! Since
I will be 70 my next birthday, if I lived 620 million years ago I would be almost
76 years old instead of 70.
Wow, now I feel a little bit
younger (grin), how about you? All you
young people out there have a great day now, you hear? You have an extra two hours to enjoy it that I
bet you didn’t know you had.
While you're fingering all that out, find out how old your dogs are using they age relative to human years. :-)
ReplyDeleteThe two oldest ones are almost my age.
ReplyDeleteYep, i do. And i knew days weren't 24 hours, cause of having leap years.
ReplyDeleteAll I know is that some days go on forever. Others are way too short.
ReplyDelete