Saturday:
It’s a moonless August morning. The first remnant of dawn has not appeared yet.
Suddenly, you notice a large softly radiant pyramid of light in the east sky.
The base of this ghostly triangle is along the east horizon and the peak
stretches two or three fists held upright and at arm’s length above the horizon
about two hours before sunrise. Don’t be scared. It’s not really a ghost. It is
an effect called the zodiacal light. This light comes from sunlight reflecting
off dust grains in our solar system. The effect is the most visible when the
band of constellations called the zodiac makes a steep angle with the horizon.
You need a clear dark sky with no haze or light pollution to see the zodiacal light.
At its brightest, the zodiacal light rivals the light of the central Milky Way.
This is one of the best times of year to see the zodiacal light in the morning.
This is
also one of the best times of the year to see meteors. The Perseid meteor
shower peaks early next week. But you should see increased meteor activity
later this week just below the W of the constellation Cassiopeia. This point is
about two and a half fists held upright and at arm’s length above the northeast
horizon at 11 p.m. By dawn, this point is about seven fists above the northeast
horizon
Sunday: At
9 p.m., Venus is about a half a fist above the west horizon and Saturn is two
fists above the southwest horizon. How’s that for an uncreative description of
the night sky?
Monday:
Let’s all sing the galactic black hole monster song: “D is for dusty, that’s
good enough for me. D is for dusty that’s good enough for me. D is for dusty
that’s good enough for me. Oh dusty, dusty, dusty starts with D.” Astronomers
know that spiral galaxies such as our own have super massive black holes in the
center, black holes that are billions of times the mass of the Sun. They
thought they got to be this massive by mergers where two galaxies collide and
the gas, dust and black holes at the center of each colliding galaxy form a
larger central black hole. But many distant galaxies show no signs of galactic
mergers. Astronomers think the black holes at the center of these galaxies grew
simply by snacking on the gas and dust that comes from supernova explosions and
normal star formation. Just like the Cookie Monster gains weight by snacking on
individual cookies rather than eating a cookie factory. Cookie crumbs, I mean
dust, block your view of the center of our galaxy. It is about one fist above due south at 10 p.m., between the
constellations Sagittarius and Scorpius. For more information, go to http://goo.gl/GRrWa.
Tuesday: Hercules
stands almost directly overhead at 10:30 this evening. Four moderately bright
stars form a lopsided square that represents his body, while his head points
southward.
Wednesday:
School starts in about a month so it is time to start reviewing your geometric
shapes. Let’s start with the right triangle that is a fist above the
west-southwest horizon at 10 p.m. The bluish star Spica is at the right angle,
in the lower left corner of the triangle. Saturn is a half a fist above Spica
and Mars a fist to the right of Spica.
Thursday: First
mentioned exactly a month ago, Bellatrix Lestrange is Sirius Black’s cousin.
But, far from being kissing cousins. They are killing cousins. Bellatrix kills
Sirius in a fight at the Ministry of Magic. Bellatrix the star is the third
brightest star in the constellation Orion the hunter. You can find it two fists
above the east horizon at 5 am. But, don’t turn you back on it!
Friday: When
you got up early yesterday, you may have noticed a very bright point of light
two and a half fists to the left of Bellatrix and two fists above the east
horizon. That is the planet Jupiter. Mars is a fist to the lower left of
Jupiter. Continue following the line from Jupiter to Mars and you’ll reach the
elusive Mercury. It is less than a half a fist above the northeast horizon.
The
positional information in this column about stars and planets is typically
accurate for the entire week.
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