Word of the Day

Perihelion

Today, (actually last evening after midnight) our planet earth reached its closest position in its annual orbit around the sun.  This is called perihelion.  To be sure that is about three million miles closer than our position with the sun in June of this year when we will be stretched furthest away.  Called aphelion   

You're probably scratching you head over the fact that the overnight temperatures have plunged into the single digits lately.  If we're closer to the sun why aren't we warmer?  That would be a consequence of the tilt of the earth on its axis.  Living in the northern hemisphere we're tilted away from the sun and it is wintertime.  If you live in the southern hemisphere you are tilted in the direction of the sun and it is summertime.  You may recall that only a couple of weeks ago we celebrated the winter solstice - that time when we are tilted the furthest from the sun.  The proximity of perihelion with the solstice is merely coincidental.

If you want to impress your acquaintances and coworkers here is a fun factoid.  Astronomers tell us that the earth is distancing itself from the sun at a rate of about 1.5 centimeters a day.  While that might add-up over the course of billions of years we're still attached at the hip with our closest star.

As with all stars the fate of our sun is preordained.  As it ages and begins to run out of fuel it will morph into a red giant phase; and all the planets closest to the sun (including earth) will be incinerated in a spectacular and fiery denouement.  We're toast!

Have a good day.

And you're welcome.