Mon Mar 28
MILKY WAY OVERVIEW
We live in a spiral galaxy, the disc of which is about a hundred thousand lights years, or 600,000 trillion miles
across. It‟s made up of maybe a couple hundred billion stars. A lot of these stars are found in the nuclear bulge
at the center of the galaxy. And there is a spherical halo of stars surrounding the bulge and the disc. We live in the
disc, in the Orion Perseus arm, a little over halfway out from the center to the edge of the Milky Way. That arm is
visible in our current evening sky. There are three other arms in the Milky Way: the Sagittarius-Carina arm, best
seen in the late spring and early summer, an unnamed arm on the opposite side of the galaxy, which can‟t be seen
directly because of dust and gas in the galactic disc which blocks our view of it, and lastly the Cygnus arm, which can
be seen during the summer and fall of the year.
Tue Mar 29
SEASONAL CONSTELLATIONS
We are now more than a week into the new season, and spring has definitely sprung. The weather change this far south is
subtle - a few new fragrances in the air, new growth, and of course, all that pollen. But the change of seasons has also
brought a change in the constellations. Orion the Hunter and his entourage - Taurus the Bull, the greater and lesser dogs,
Auriga the Charioteer and the Gemini twins – have slipped over into the western sky; while new star groups rise out of the
east. The stars of Leo the Lion appear as a backwards question mark above the eastern horizon, while the Big Dipper
stands on its handle in the northeast after dusk; and soon bright Arcturus in Bootes the Shepherd and the star Spica in
Virgo the Maiden will rise. The sky wheels about us, and the springtime constellations take their places in the heavens.
Wed Mar 30
MOON AND VENUS IN PREDAWN SKY
If you go outside tomorrow morning before sunrise, you may be able to see the moon and the planet Venus close together,
low in the eastern sky. The moon will appear as a very slender crescent, near the east horizon. Look to the right of the
moon, and you should also see a very bright star, which is actually the planet Venus. The moon passes by Venus once a
month, and when they appear close together, it‟s called a conjunction. Of course, this is a bit of an illusion – the moon is
just a couple of hundred thousand miles away, while Venus is millions of miles farther out. But our depth perception
doesn‟t work for such great distances, and to the human eye they seem to be right next to each other. If Venus was
actually just a couple of hundred thousand miles away, it would be an impressive sight: imagine what the moon would
like if it were sixteen times larger, and you get an idea. Of course if Venus were ever that close to us, a collision would be
unavoidable, so it‟s probably a good thing that it‟s way out there!
Thu Mar 31
OUT WITH THE RAM
March comes in like a lion and goes out like a lamb. This saying is meant to refer to the improving weather in the
springtime of the year. But there is also an astronomical connection. At the beginning of March, the constellation Leo the
Lion makes its way into the evening sky, appearing in the east after sunset. As the month progresses, Leo appears a little
higher in the sky each night, while in the west, many constellations of the late fall and early winter are sinking toward the
horizon. By the end of March, one of our winter constellations makes its exit in the western sky. For the past few weeks,
the sun has been steadily encroaching on this constellation, as the earth‟s revolution has caused the sun to slowly slip
eastwards against the background of distant stars. Now the sun is about to pass between us and the constellation Aries the
Ram. March comes in with the Lion and goes out with the Ram.
Fri Apr 1
APRIL FOOLS
Long ago in Europe, the new year began not on January 1st, but on March 25th, which at that time also marked the
beginning of spring. People were so glad winter was over, they partied for about a week, right up through the first day of
April. Then came the Gregorian calendar reform in 1582, and France was first to adopt the new system. The French king
Charles the 9th decided this was also a good time to move the new year‟s celebration from the end of March to the
beginning of January, where it is now. But some people just didn‟t get it, and continued to observe the new year on April
1st. These people were laughed at, and called “poisson d'avril," or “April Fish” by their more sophisticated countrymen.
And this is the origin of our modern April Fool‟s Day. No fooling.
Mon Apr 4
ASTRONOMY GEOGRAPHY: PLACES IN THE SKY
Of the eighty-eight officially recognized constellations in the sky, can you identify the seventeenth largest one? It is
bordered on the north by Auriga and Perseus, on the south by Eridanus, on the west by Aries, and on the east by Orion.
Within its borders are such deep sky objects as the Crab nebula, the Hyades star cluster, and the better-known Pleiades, or
Seven Sisters. This constellation‟s brightest star is Aldebaran, a red giant forty times larger than the sun. One of the oldest
star patterns, in mythology this animal is sometimes seen as a representation of Zeus, who carried the princess Europa
across the sea to Crete; or as the seventh labor of Hercules. Can you name this star figure, the second constellation of the
zodiac? The answer is Taurus the Bull, currently visible in the western evening sky.
Tue Apr 5
SUN, SOLAR YEAR AND ECLIPTIC
Watch the sun and you‟ll discover it gets around. But of course you can‟t watch the sun, because it‟s too bright to look at
without hurting your eyes. If you could somehow dim down the sun enough, you could also see the stars in the sky at the
same time. (Actually, there are times when this happens – during total solar eclipses.)Assuming you could see the sun and
stars at the same time, you‟d notice the sun drifts eastward like the moon, although not as fast as the moon. The moon
moves 13o a day; the sun only moves about 1o a day. After 365 days, the sun would return to conjunction with the star it
had been beside exactly a year ago. A solar year, then is the amount of time it takes the sun to go once around the
heavens, and the invisible line that traces out that path is called the ecliptic. The constellations through which the sun
passes each year is called the zodiac, and the ecliptic is its central line.
Wed Apr 6
MOON „TWIXT ARIES AND TAURUS
Tonight the waxing crescent moon lies on the border between the constellations Aries the Ram and Taurus the Bull. The
region of the sky containing Aries is empty of bright stars, other than Hamal and Sheridan in the Ram‟s head. Ancient
Sumerians often saw these stars as a great sword or scimitar, and to the Pharaohs of old Egypt it was associated with the
sun god Amon Ra. Above the moon is the Pleiades star cluster, and above the Pleiades is the star Aldebaran, the eye of
Taurus the Bull. Aries and Taurus, along with a great many other constellation figures, relate to the adventures of the
Greek hero Hercules. Aries represents the golden fleece, sought by Jason and the Argonauts, which included Hercules,
although he left the expedition at Mysia. And Taurus is sometimes portrayed as the bull given by Poseidon to King Minos
of Crete. This bull was later captured by Hercules as one of his twelve labors.
Thu Apr 7
THE MOON‟S TIDAL LOCK
The moon is a fat crescent tonight; it shines in the south after sunset. It shines not by its own light, but by reflected
sunlight. Half the moon is always in sunlight; half is always in shadow, just like on earth. And just as we experience daylit
and dark periods on earth, so the moon has both day and night. But the moon‟s rotation is slower than ours; a lunar day
lasts two weeks, followed by two weeks of lunar night. As the moon orbits the earth, we can‟t always see the entire
illuminated part. The moon‟s period of rotation exactly matches its period of revolution, so it rotates once for every one
orbit. This is called a tidal lock, an effect of the earth‟s tidal pull on the moon, which has slowed down its rotational speed
to be in synch with its revolution. Because of this we can only see half the moon (lunar nearside;) the farside of the moon
(sometimes wrongly called “the dark side,” ) can never be seen from earth. Or as Pink Floyd tells us, there is no dark side
of the moon; matter of fact, it‟s all dark!
Fri Apr 8
HOW TO LOSE WEIGHT
If you want to lose weight, you might consider moving to the equator. Here‟s why: The Earth is rotating, creating
centrifugal force - not really a force, just inertia at work – like when your car turns a corner, you‟re pushed against the
side of the car – actually it‟s just you travelling in a straight line as the car turns. The Earth‟s spin hurls us out into space,
but gravity holds us back. Earth‟s rotational speed is zero at the poles, but almost a thousand miles an hour at the equator.
And the Earth is a little fatter around the equator than from pole to pole. So at the equator we‟re 12 miles farther away
from Earth‟s center, and there‟s slightly less gravity. This reduces our weight by a half of a percent overall, or about twotenths of one percent from our position here in Florida. So if you weigh 150 and move to Ecuador, you‟ll weigh about a
third of a pound less.