Saturday: Who
can forget that memorable song by Three Dog Constellations Night, “The sky is
black. The stars are white. Together we learn to find the light.” Well, maybe
it didn’t go like that. This is good because not all stars are white. Most
stars are too dim to notice a color. But, the stars in the constellation Orion
provide a noticeable contrast. Betelgeuse, five fists held upright and at arm’s
length above due south at 10:30 p.m. is a red giant. Rigel, the bright star
about two fists to the lower right of Betelgeuse, is a blue giant.
By the
way, the three dog constellations are Canis Major, the greater dog; Canis
Minor, the lesser dog; and Canes Venatici, the hunting dogs. Canis Major
contains Sirius, the brightest star in the nighttime sky.
Sunday: Mars
is halfway between the crescent moon and the southwest horizon at 5 p.m. You
may need binoculars to see it, even if the horizon is clear.
Monday: How
do you study the life cycle of a dog? Easy. Get a dog from the animal shelter,
care for it for 15 years and study it. How do you study the life cycle of a
star? Easy. Pick a star, watch it for a few billion years, and…. Wait a minute.
Astronomers can’t observe something for a few billion years. Instead, they
study stars that are at different points in their long life cycle and piece
together the information from those different stars. What they do is like
studying a one-year-old dog for a few minutes, then studying a different
two-year-old dog for a few minutes, and so on. The sky in and near the
constellation Orion provides an example of four objects at different points of
star life.
First,
find Rigel, the bright star in the lower right corner of the constellation Orion.
This star, rapidly burning its fuel for a high energy but short lived
existence, is three and a half fists above due south at 9:30 p.m. About one
fist up and to the left are the three objects of Orion’s sword holder. The
middle “star” is really a star-forming region called the Orion nebula. There
you’ll find baby Suns. Now, look about two fists to the right and a little
below Rigel. You should be looking at a star that is about one tenth as bright
as Rigel but still the brightest in its local region. The third star to the
right of that star is Epsilon Eridani, the most Sun-like close and bright star.
Betelgeuse, in the upper left corner of Orion, is a star at the end of its life
that started out life a bit larger than the Sun.
Tuesday: Jupiter
is six fists above the south horizon at 8 p.m.
Wednesday:
What you see with the naked eye isn’t all that can be seen. While astronomers
can learn a lot from observing the sky in the visible wavelengths, many
celestial objects radiate more light, and more information, in wavelengths such
as radio, microwave, infrared, ultraviolet, x-ray, and gamma ray. Last year,
NASA launched the Wide-field Infrared Survey Explorer (WISE) to study objects
that radiate in the infrared range such as asteroids, cool dim stars, and luminous
galaxies. For an interesting comparison of how different wavelengths show
different aspects of a galaxy, go to http://goo.gl/nvuax. If it weren’t for
infrared telescopes such as WISE, astronomers would not know about the
significant amount of dust in galaxies.
Thursday:
January is the coldest month of the year so it is time to turn up the furnace.
Fornax the furnace is one fist above due south at 7 p.m.
Friday: Tonight’s
first quarter moon is in the constellation Aries the ram.
The
positional information in this column about stars and planets is typically
accurate for the entire week.
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