Saturday:
Mnemonics are helpful for remembering astronomy facts. (Similarly, “Johnny
Mnemonic”, the 1995 cyberpunk film, was helpful in getting Keanu Reeves’ career
going.) After all, school children all around the country are learning the
order of the planets by remembering, “My very excellent mother just served us
nine….” Oops, I guess that one needs updating. Well, here’s one that will not
need updating for nearly 100,000 years: the order of the stars in the Big
Dipper. Because the nighttime stars are so far away from us, their actual
motion through the sky, called their “proper motion” is not noticeable over
even thousands of years. That is why the constellations have remained the same
since ancient times. But two stars in the Big Dipper have a proper motion large
enough such than in 100,000 years, the stars will no longer make a dipper
shape. Until then, you can remember the names of the seven dipper stars in order
from handle to cup by remembering this helpful advice for teens: “AM, ask mom.
PM, dad”. The stars are Alkaid, Mizar, Alioth, Megrez, Phad, Merek, and Duhbe.
The Big Dipper is one fist held upright and at arm’s length above the north
horizon at 11 p.m.
Sunday: To
the people of Ancient Greece, the stars that are about five and a half fists
above the east-northeast horizon at 10 p.m. were known as Cassiopeia and
Andromeda, a mythological queen and her daughter. But not all cultures imagined
the same pictures in the sky. To the people of Polynesia, the stars of
Cassiopeia and Andromeda represented a dolphin, called Kwu. Cassiopeia formed
its tail, the brightest stars of Andromeda formed its fins, and its fainter
stars outlined the dolphin’s body.
Monday: Three
planets are crowded around the setting Sun. Venus, the brightest, is one fist
above the southwest horizon. Saturn is about a fist and a half to the right of
Venus. Mercury is below Saturn, just barely above the horizon.
Tuesday: Uranus
is in opposition tonight. That doesn’t mean that Uranus is in the minority
party in the senate. Opposition means that Uranus 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 a planet. Uranus is about four and a half
fists above the south horizon at 1 a.m. It is three and a half fists above the
southeast horizon at 10:30 p.m. You’ll need binoculars to find it. First find
Deneb Kaitos, the brightest star in the constellation Cetus the sea monster, one
and a half fists above the southeast horizon. Deneb Kaitos is the same
brightness as the North Star. If you imagine the distance from the horizon to Deneb
Kaitos as one unit, move your binoculars straight up from southwest two more of
those units. Uranus will be in the center of your field of view. Check that
same spot over the next few night. Uranus will move slightly with respect to
the distant stars.
Wednesday:
Mars is about to get eaten by a lion, a constellation lion. It is right in
front of the head of Leo the lion, three fists above the east horizon at 6 a.m.
Thursday: Keep
an eye out for Jupiter which is slowly creeping into the pre-midnight sky.
Tonight it rises at about 11:45 p.m. By 12:30, it is a half a fist above the
east-northeast horizon.
Friday: The
constellation Orion is four fists above the south horizon at 6 a.m. The Orion
is a cloud of gas and dust visible with binoculars about a half a fist below
the “belt” of three stars. If you are feeling especially attracted to the
nebula, that might be because astronomers think there may be a black hole in
the middle. They have not directly observed the back hole, which would be the
closest known one to Earth at a distance of 1,300 light years. But the motion
of stars in the region is consistent with them being near a black hole 100
times the mass of the Sun. For more information, go to http://goo.gl/AGjFf.
The
positional information in this column about stars and planets is typically
accurate for the entire week.
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