Be a considerate neighbor: Reduce nighttime glare.
Shield all your outside lights downward (or turn them off completely)
and enjoy the beautiful, starry night sky.
November 2006 night sky
THE SIGN OF THE CRANE
This is a good time to get out away from the city lights and see
a southern-hemisphere constellation. Just above the southern horizon,
due south at 8 p.m. is Grus, the Crane. Grus lies just below the
constellation Piscis Australis and the bright star Fomalhaut.
This is a true southern constellation, as it lies about thirty
degrees south of the celestial equator. When you are looking at
this constellation, you are actually looking down through the bottom
of the Milky Way's disk into open space. Because of this, the star
field around Grus is sparse. But get out your binoculars, because
this constellation has a couple of great binary stars to observe.
Before we explore the doubles, let's look at the alpha star of
this constellation, Al Nair, or "The Bright One." Al Nair,
marking the crane's southwestern foot, cannot be seen at all above
about forty-two degrees north latitude. This star is the thirty-first-brightest
star in the sky. It is a hot blue subgiant with a surface temperature
2.3 times hotter than the Sun. At a distance of about a hundred
light-years, Al Nair shines with the brilliance of 380 suns. Like
most stars in its class, it spins rapidly, giving it a rotational
period of under a day. It is believed that Al Nair is close to the
end of its normal hydrogen-fusing lifetime.
Now we can enjoy the doubles. The two stars of delta Grus are
visible even with the naked eye. Delta Grus consists of a 3.97 magnitude
star and a 4.11 magnitude star. Remember that larger magnitude numbers
are dimmer and the dimmest star visible to the naked eye is about
sixth magnitude. Looking through the binoculars, you should see
the two stars of contrasting colors, red and yellow.
A bit fainter is the double mu Grus. It, too, can be viewed with
the naked eye, but binoculars are recommended for this one. The
two stars are both G8 giants, of 4.79 magnitude and 5.10 magnitude.
And, if you are up for a challenge, get out your telescope and find
the binary theta Grus. Its components are of fourth and seventh
Also in Grus, 132 light-years away, is a sun-like star with a
planet circling around it. The star has the very scientific-sounding
name of HD 213240. Its planet was discovered in 2001 by Geneva Observatory,
by watching its parent star wobble. Though this planet is 3.7 times
larger than Jupiter, it orbits in the Habitability Zone. This means
that the planet my have Earth-like temperatures, with liquid water
available in its atmosphere. Or it may have moons that have water.
This leads to the speculation of life. Certainly, if there is water,
there could be living things. Unfortunately, we earthlings may never
know for sure.
THE PLANETS AND MOON
Like last month, planet viewing will be very difficult.
• You may be lucky to catch Mercury on the western horizon
at about 6:30 p.m. on November 1 and 2, just below Jupiter.
• On November 8, Mercury will slowly slide across the face
of the Sun during an event known as a “transit.” If
you have a safe method to project the Sun on a white surface or
have a solar filter for your telescope, you can see Mercury perform
its transit, starting at 12:12 p.m. and ending at 5:10 p.m. It
will look like a dot slowly moving across the face of the Sun.
The transit of a planet across the face of the Sun is a relatively
rare occurrence. As seen from Earth, only transits of Mercury
and Venus are possible. There are approximately thirteen transits
of Mercury each century. The last time North America had the chance
to see a transit by Mercury was in 1960.
• Venus and Mars are in the glare of the Sun this month.
• Jupiter is on the western horizon early in the month just
after sunset, but quickly plunges closer to the setting Sun this
month and will not be visible after the first week.
• Saturn is for those who are up after midnight. It rises
in the east about 1:30 a.m. early in November, and around 11:30
p.m. at the end of the month.
• The Moon is full on November 5 and new on November 20.
If you have a question, comment, or suggestion
for Charlie, e-mail him at: firstname.lastname@example.org.