Saturday: Tonight is a great night to look for the Big Dipper. Tomorrow will be a great night to look for the Big Dipper. In fact, every night for many centuries will be great nights to look for the Big Dipper. But the Big Dipper’s shape slowly changes over many, many, many, many centuries. (Have I reached my word count yet?) Tens of thousands of years ago, it didn’t look like a dipper and tens of thousands of years from now, it will no longer look like a dipper. For a short video simulation of the changing Big Dipper, go to https://youtu.be/txJH8RlIoXQ. For a look at the current Dipper, face northeast at 8:00 p.m. The lowest star, Alkaid, is two fists held upright and at arm's length above the horizon.
Sunday: The moon is a half a fist above the
east-southeastern horizon at 11:00 p.m. The bright star Spica is a little over
a half a fist to the upper right of the moon.
Monday: Last week we learned that Clyde Tombaugh discovered
the first planet 9. Will you discover the new Planet 9? You and thousands of
others will have the opportunity to comb through images of the sky from NASA’s
Wide-field Infrared Survey Explorer (WISE). You’ll view short “flipbook” movies
of the same patch of sky on different nights. Any point of light that moves
could be Planet 9 or another undiscovered Solar System object. Read about how
you can join the search for Planet 9 at http://tiny.cc/fh4jtz.
Tuesday: Very bright Venus is nearly one and a half fists
above due southeast at 6:15 a.m. Mars is halfway between Venus and the horizon.
Mercury is just above the east-southeastern horizon.
Wednesday: It’s getting dark. The last remnant of twilight
has disappeared. Suddenly, you notice a large softly radiant pyramid of light
in the western sky. The base of this ghostly triangle is along the west horizon
and the peak stretches two or three fists above the horizon. It is 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. Look for the ghostly patch after twilight for the next few
weeks.
Thursday: On these late winter mornings, it is still
difficult to get going. You just want to plop into a chair and sit still. But,
are you really sitting still? You’re moving at about 700 miles per hour due to
the rotation of the Earth on its axis and 66,000 miles per hour due to the
revolution of the Earth around the Sun. If that’s not enough, the entire solar
system is orbiting the center of the galaxy at a whopping 480,000 miles per
hour! So while you may be sitting still with respect to your living room (and
all of the overachievers in your house), you are NOT sitting still with respect
to the center of the galaxy. For more information about this concept, go to https://nightsky.jpl.nasa.gov/docs/HowFast.pdf.
Friday: Two bright stars, Vega and Deneb, are hugging the
northern horizon together at 11:00 p.m. Vega, the brighter of the two, is about
a half a fist above the northeastern horizon. Supergiant Deneb to two and a
half fists to the left of Vega, closer to due north.
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.