Tue Jan 1, 2013
JANUARY AND THE NEW YEAR
January is named for Janus, the Roman god of new beginnings: He had two faces, one which looked back toward the past,
and another which looked forward to the future. This is also the year Twenty Thirteen, which according to the calculations
of a Roman monk, Dionysius Exiguus, marks the 2 thousand and thirteenth year following the birth of Christ – AD –
Anno Domini – in the year of Our Lord - 2013. Dionysius was a good historian, but his count is off by at least one year.
Our calendar goes from 1 BC to AD 1 – there is no zero year, because the numerical concept of zero was not used in
Europe back then. “Zero” was later introduced by mathematicians from India and the Middle East. Here’s another puzzle why does the new year start now? There's nothing particularly special about this time of year, astronomically speaking;
and astronomers are the ones who invented calendars in the first place. Before 1751, New Year's in America used to start
on March 25th, the beginning of spring. Well, no matter how you reckon time, the earth just keeps on rolling along.
Wed Jan 2, 2013
PERIHELION
The earth's orbit is slightly elliptical, so its distance from the sun changes through the year. The earth reached perihelion at
midnight last night. Perihelion is the point in its orbit when earth is closest to the sun. On average, we're about 93 million
miles from the sun, but right now, we are just a little under 91 and a half million miles from our parent star. So if we're a
million and a half miles closer to the sun, how come we're having winter? Well, not everyone on earth is having winter;
summer has just begun for folks who live below the equator. Our seasons are not caused by our slight variation in
distance, but by the 23 and a half degree tilt of our planet as it orbits. Now our north hemisphere is tipped away from the
sun; this puts the sun lower in our sky, and with less direct sunlight we get cooler temperatures. Tonight look for two
bright “evening stars” - the planet Mars low in the southwest and the planet Jupiter high in the eastern sky after sunset.
Thu Jan 3, 2013
ROBERT FROST AND CANIS MAJOR
The American poet Robert Frost was a keen observer of the world and nature. In his writing, Frost often captures the
simple majesty of the Universe. You notice it in his poem, the Star Splitter, in which he begins by telling us, “You know
Orion always comes up sideways,” as indeed he does, first the forward shoulder and leg, then the hunter’s belt, and lastly
the trailing shoulder and knee. Orion now holds a prominent place in the southeast sky after sunset. If you trace the stars
of his belt downward, you will find the star Sirius in the constellation of the Big Dog, Canis Major, and Frost wrote a
poem about this heavenly hound as well. Frost places Sirius in the dog’s eye when he says: “The great Overdog That
heavenly beast With a star in one eye Gives a leap in the east. He dances upright All the way to the west And never once
drops On his forefeet to rest.” Because of the earth’s rotation, Canis Major does move across the sky just the way Frost
describes it.
Fri Jan 4, 2013
ELUSIVE MOON AND SATURN,VENUS
Moon watchers have had to work extra hard lately; each day the moon rises nearly an hour later than it did the day before.
That’s fine for when the moon is going through its waxing phases: For the first two weeks after the new moon our satellite
is already up in the sky after sunset. When the moon is full, as it was toward the end of December, it rises at sunset and
sets at sunrise – in other words, the moon is up all night long! But now the moon is in its third quarter, and it won’t rise
until more than a half hour past midnight, and on Saturday night, or I should say, Sunday morning, you’ll have to go out
after 1:30 in the morning to see it. Alternatively, you could go outside just before sunrise on Sunday, and then you will
find the moon well up in the southeast sky. Off to the east of the moon – that’d be to the left of it and slightly down –
you’ll find the planet Saturn, appearing as a slightly yellow-tinged star. And near the eastern horizon another planet,
Venus, shines as a bright morning star.