Saturday: Jupiter is one and a half fists held upright and at arm’s length above due southeast at 9:00 p.m. Saturn is about two fists to the right of Jupiter.
Sunday: “Excuse me, do you have the time?”
“No, but the Big Dipper does.”
You can use the orientation of the Big Dipper to tell time
with a precision of about 15-30 minutes. First, find the two stars at the far
end of the Big Dipper cup, the stars that do not touch the handle. Draw an
imaginary line segment starting at the North Star and passing through the two
Big Dipper cup stars. Now, draw a big circle around the North Star. Your circle
is a 24-hour clock. Number the circle from 0 hours at the top, counterclockwise
to 12 hours at the bottom of the circle, and back up to 24 hours at the top. (O
hours and 24 hours are the same on this clock because the day is 24 hours
long.) The hour number on the big circle closest to where your imaginary line
intersects this circle is called your raw time. Due to the location of the Big
Dipper compared to the rest of the stars, the time nearest the intersection
(the raw time) is correct for March 6. For any other night, subtract two times
the number of months the current date is after March 6 from the raw time. For
example, let’s say the imaginary line between the North Star and the Dipper
stars is pointed to the right. That means the raw time is 18 hours or 6 p.m. If
you made this observation tonight, which is six months after March 6, you would
subtract two times six or 12 hours from the raw time. Don’t forget to
convert for daylight savings time if needed. For a more complete explanation on
how to do the Big Dipper clock math, go to http://goo.gl/02HmA.
If you prefer a more visual tool, and a fun project to do with your kids, there
is a simple “star clock” template and instructions at https://skyandtelescope.org/observing/make-a-star-clock/.
Use this paper star clock whenever your watch is broken. The Big Dipper is in
the northwestern sky at 9:00 p.m. tonight.
Monday: Labor Day was the brainchild of labor unions and is
dedicated to American workers. The first Labor Day was celebrated in 1882. The
Greek mythical hero Hercules probably wished there was a Labor Day to
commemorate his work. As punishment for killing his family while he was
temporarily insane, he had to perform twelve nearly impossible tasks such as
killing monsters or stealing things from deities. Hmmm. Maybe we shouldn’t
commemorate his labors. But we can enjoy his constellation. The keystone
asterism representing the body of Hercules is six fists held upright and at
arm’s length above the western horizon at 10:00 p.m. For more information about
the Labors of Hercules, go to http://goo.gl/ozVF5.
Tuesday: School starts this week so it is time for a little
geometry review. A square is a regular quadrilateral. This means it has four
equal sides, four equal angles, and wears old fashioned clothing. Go outside at
10:00 p.m. tonight with a notebook in hand to sketch one. The Great Square of
Pegasus is balancing on its corner three fists above the eastern horizon. The
top corner of the square is two fists above the bottom corner. The other two
corners are to the left and right of the line segment connecting the top and
bottom corners.
Wednesday: Venus is one and a half fists to the left of the
waxing crescent Moon at 8:00 p.m. They are low in the south-southwestern sky.
Thursday: Geometry review, part 2. Go outside at 10:00 p.m.
tonight with a notebook in hand. (Good teaching involves a little repetition.)
A triangle is a polygon with three corners and three line segments as sides. A
good example is the Summer Triangle made up of the bright stars Vega, Deneb and
Altair. Altair is five fists above the southern horizon. Vega, the brightest
star in the triangle, is seven fists above the western horizon. Deneb is a
little bit east of straight overhead.
Friday: The asteroid Pallas is at opposition tonight. That
doesn’t mean that Pallas says “no” when you say “yes”. Opposition means that
Pallas is on the opposite side of the Earth as the Sun. When an object is in
opposition, it is at its highest point in the sky during the darkest time of
the day. Thus, opposition is typically the best time to observe an asteroid or
planet. Pallas is three fists above the southeastern horizon at 10:00 p.m.
First find bright Jupiter in the center of your binoculars’ field of view to
the somewhat bright reddish star Hydor. Then, with Hydor at the center of your
field of view, move your binoculars about one and a half fields of view to the
upper left to reach Pallas. It is in the middle of a small parallelogram. As
the days go by, Pallas moves to the lower right compared to the parallelogram.
The positional information in this column about stars and planets
is typically accurate for the entire week. For up to date information about the
night sky, go to https://nightsky.jpl.nasa.gov/planner.cfm.
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