One of the most fascinating astronomical events late this year is the
occultation, or obscuring, of a bright star by the moon. You can watch
this event with the naked eye. Watch shortly after midnight as December
12 turns into the 13th, and see the moon slowly creep up on Aldebaran (the
brightest star in Taurus, the Bull), finally blocking it out by 12:15 a.m.
(exact time depends on your location).
Only four bright stars can ever be occulted by the moon. They are Antares
in Scorpius, Aldebaran in Taurus, Regulus in Leo and Spica in Virgo. Each
will be occulted in a series that repeats roughly every 18 years.
The Planets
Mercurythis elusive planet makes a brief evening appearance late in
November, lying near the southeastern horizon after sunset. Not an easy
object to see at this time of year.
Venus is brilliant, shining brightly in the southwest during your drive
home from work during any clear evening. Its magnitude reaches 4.7 by
mid-December, its most brilliant point of the year. The ease of visibility
of Venus will generate the often-asked question, “Was Venus the Christmas
Star?” While unlikely, the Christmas Star puzzle is an intruiging astronomical
detective story told in our Christmas planetarium show each year. A lovely
crescent moon joins Venus on November 3 and 4 and on December 3 in the
western sky after sunset.
Mars lies quite close to Venus now, lying along the same line of sight.
Of course, the two planets are not near each other in reality. By December
22 Mars lies 1.1 degrees south of Venus. Mars shines dimly at magnitude
+1.2, making the brightness difference between Mars and Venus almost six
magnitudes. Mars passes 0.59 degrees from Uranus on the night of December
27. Uranus is a dim 6th magnitude, detectable in binoculars or telescope,
not with the unaided eye. It is staggering to realize that Mars lies a
scant 192 million miles from Earth, whereas Uranus is exactly 10 times
further away, at 1.9 billion miles.
Jupiter is brilliant in the constellation Capricornus. It is visible
during most of the evening in November, but sets by 8:30 p.m. in mid December.
Jupiter is the bright object in the southern sky, seen right after sunset.
Look for the first quarter moon alongside Jupiter on November 7.
Saturn is high in the south by 10 p.m. during November, and a couple
of hours earlier by December. No other bright objects lie in this region
of the sky, so Saturn should be easy to spot. Through a telescope it is
a superb sight, revealing the delicate ring system. Try one of our telescope
observing nights to view the ringed planet.
Moon Phases
New Moon 1st Qtr Full Last Qtr
Nov 7 Nov 14 Nov 21 Nov 30
Dec 7 Dec 14 Dec 21 Dec 29
Planetarium Shows
Every Friday at 4 p.m. the Henry Buhl Jr., Planetarium at Carnegie Science
Center presents Stars Over Pittsburgh, your weekly guide to the current
night sky.
Dont forget to see Flashback to the Future, celebrating the 40th anniversary
of the Space Age, and our traditional Christmas show, The Christmas Star.
Martin Ratcliffe is the past director of the Henry Buhl, Jr. Planetarium
& Observatory. He is now director of Science Theaters and Media Services,
The Exploration Place, Wichita, Kansas.
Using the Star Map
Find a dark observing site, away from bright street lights and porch
lights. You should also give your eyes time to adjust to the darkness.
To avoid hampering your night vision and give yourself just the right amount
of light for reading the map, place a small brown paper bag over a flashlight.
If you dont know which direction youre facing, look for the Big Dipper,
or Ursa Major. Then follow the two stars at the end of the dippers bowl
across the sky to the north star, or Polaris, and you will be facing north.
East is to your right, west is to your left and south is behind you.
When you look at this map, you might think that east and west are reversed.
They are opposite from the directions on a road map, but when you hold
the star map over your head and look up at it, east and west fall into
place. The stars on the map now should match the stars in the sky.
The north star is the only star in the sky that never moves. Throughout
the night and year, all the stars move in circles around Polaris, also
called the “pole star” since it is located directly over the Earths north
pole.
As the night progresses, the stars will slowly move from east to west,
circling around the pole star, or Polaris, due to the Earths rotation.
Because the Earth is also moving around the sun, the stars appear a bit
farther to the west at the same time each night.
