Photograph of the Moon in February, a couple of
days before the official full moon.
March 2006 night sky
March is a great month to go outside and find some of the brightest
stars in the night sky. The brightest is Sirius, the Dog Star, located
in Canis Major. Sirius can be seen from every inhabited region of
the Earth's surface. To find Sirius, look for Orion's belt. Use
the belt stars as a pointer and look high in the southwest. The
brightest star is Sirius.
Blazing at a visual magnitude of -1.42, it is twice as bright
as any other star in our sky. Intrinsically, Sirius is over twenty
times brighter than our Sun and over twice as massive. At a distance
of 8.7 light years, it is not the closest star system; the Alpha
Centauri system holds this position.
A smaller companion star, Sirius B, was discovered in 1862, by
Alvan Graham Clark. In 1915, astronomers at the Mount Wilson Observatory
determined that Sirius B was a white-dwarf star, the first ever
to be discovered. This small, compact object is the remains of a
low-to-medium-mass star that has used up its fuel. The core shrinks
into a compact ball of hot star-stuff. Over the course of a few
hundred billion years, white dwarfs cool down to where they are
no longer visible. However, over the universe's lifetime to the
present (about 13.7 billion years), even the oldest white dwarfs
still radiate temperatures of a few thousand degrees.
Below Sirius in the southern sky is Canopus, residing in the constellation
Carina, the Keel. Canopus is a true powerhouse. Its brightness is
due to its great luminosity, not its proximity to Earth. At 310
light-years away and more than fourteen thousand times the brightness
of our Sun, Canopus is the second-brightest star.
Having run out of its hydrogen fuel, Canopus is a dying star.
It is now in the process of converting its core helium into carbon.
This process has led to its current size, sixty-five times that
of the Sun. If we were to place our solar system around Canopus,
the star would almost envelop Mercury.
Canopus will eventually become one of the largest white dwarfs
in the galaxy and may just be massive enough to fuse its carbon,
turning into a rare neon-oxygen white dwarf. These are rare because
most white dwarfs have carbon-oxygen cores. But a massive star like
Canopus can begin to burn its carbon into neon and oxygen as the
star evolves into a small, dense, and cooler object.
High in the sky above Sirius is a grouping of stars on the edge
of our galaxy. Among these stars is Procyon, in Canis Minor, the
Little Dog constellation. It is the eighth-brightest star in our
sky. Procyon is a yellow-white main-sequence star, twice the size
and seven times more luminous than the Sun. It appears so bright
because it is relatively close, at 11.4 light-years.
Procyon is orbited by a white-dwarf companion detected visually
in 1896 by John M. Schaeberle. At just one-third the size of Earth,
its companion, dubbed Procyon B, contains 60 percent of the Sun's
Finally, in the northwest is Capella, in the constellation Auriga,
the Charioteer, shining as the sixth-brightest star in our sky.
At a distance of forty-two light-years, Capella is one of the sky's
most famous double stars. Its two component stars are both yellow
class G stars with roughly the same temperature as the Sun. Both
stars are much larger and brighter than the Sun, one fifty times
more luminous, the other eighty times brighter. Each is about ten
times the size of the Sun. These stars are dying giants that have
stopped hydrogen fusion in their cores. The two stars, just below
the edge of separability in the best telescopes, are only about
sixty million miles apart, about two-thirds the distance between
Earth and Sun.
So, on a cold winter's evening go outside and let some of the
brightest stars in our night sky shine down on you.
THE PLANETS AND THE MOON
• Mercury will be visible just before sunrise in the east.
Look for the Moon to be with Mercury on March 27.
• Venus is also low in the east before sunrise. The Moon is
beside Venus on March 26.
• Mars can be found in the evening sky, setting about 11:00
p.m. Look for the Moon to stand beside Mars on March 5.
• Jupiter rises in the east about 10:00 p.m. and shines brightly
throughout the morning hours. The Moon settles in beside Jupiter
on March 19.
• Saturn is almost directly overhead about 8:00 p.m. this
month. The Moon nestles next to Saturn on March 10.
• If you are feeling brave and have a good telescope, set
it up March 25 through 27. Mercury and Uranus will be very close
together low in the eastern sky. Then look for Venus higher in the
morning sky. With Venus, you will be able to locate Neptune also
very close together.
• The Moon is full on March 14 and new on March 29.
Astronomy club holds open house
The Albuquerque Astronomical Society (TAAS) will host an open
house to highlight its programs, outreach services, and member benefits
at UNM's Regener Hall on Saturday, March 11, at 7:00 p.m. This event
is open to the general public, and admission is free..
Regener Hall is located on UNM's Main Campus, west of Popejoy Hall.
For information and a map, visit www.taas.org
or call 254-TAAS.
New comet visible before sunrise
During the next couple of weeks skywatchers will be looking for
the newly discovered Comet Pojmanski, which has just swept past
the Sun and will soon cruise past Earth on its way back out toward
the depths of the outer solar system. At the time of its discovery,
the comet was about a hundred times dimmer than the faintest stars
that can be seen with the unaided eye. But since its discovery,
the comet has been steadily brightening.
Finally, the comet is just becoming visible to the naked eye.
It is expected to put on its best showing during the last days of
February and the first week of March in the dawn sky. Currently,
Comet Pojmanski is shining at around magnitude 5, which is roughly
the same brightness as the faintest star in the bowl of the Little
The comet is in the constellation of Capricornus, the Sea Goat.
Beginning February 27, skywatchers in the Northern Hemisphere can
try locating it, very low above the horizon, somewhat south of due
east, about ninety minutes before sunrise. You can use Venus as
a guide. The comet will be situated roughly seven degrees to the
left and slightly below the brilliant planet (the width of your
fist held at arm's length is equal to about ten degrees).
Comet Pojmanski will move a little higher above the horizon every
morning. While only five degrees above the horizon on February 27,
this quickly improves to ten degrees by March 2, sixteen degrees
by March 5, and twenty-two degrees (more than two “fists"
up from the horizon) by March 9.
In the early morning sky the comet can be readily picked up in
binoculars, looking like a small circular patch of light with a
bluish-white hue and an almost starlike center. It comet will passing
closest to Earth on March 5, when it will be 71.7 million miles
away. After March 5, Comet Pojmanski will be receding from both
the Sun and Earth and rapidly fading, as it heads back out into