Saturday: Tonight’s
full moon is in the constellation. This morning’s other Moon is…. Wait a
minute. The Earth has only one Moon. True. And it has always had only one Moon.
Not necessarily true. According to the best existing model, about four billion
years ago, a Mars-sized object collided with the young Earth. The resulting
debris coalesced to form the Moon. However, this model left a mystery: why is
the Moon so asymmetric? Hardened-lava lowlands dominate the near side while the
far side is dominated by mountainous highlands. According to a recent revision
of the prevailing model, the early collision formed a large Moon and a small
Moon. Over the years, the small Moon caught up to and collided with the large
Moon. The highlands are the material from the collided small Moon. For more
information about this theory, go to http://goo.gl/6JlcA.
Sunday: 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.
Monday: Scandalous!
The goddess of love will be cozying up to the little king. Venus will be about
a pinky-width or less from the bright star Regulus, whose name mean “little
king” in Latin. At 6:30 this morning, Regulus will be just to the lower left of
Venus, three fists above the east horizon. Because Venus is so close to the
Earth, it moves an easily noticeable amount in the sky each day. Compare its
position to that of Regulus for the next few days.
Tuesday: The
smoke is starting to clear so we can see objects in the sky better than we
could a few weeks ago. Luckily the Big Bear Solar Observatory in California doesn’t
have this problem. Astronomers have improved the optics of the telescope so
much that it is able to resolve features on the surface of the Sun that are just
a few miles across. Remember, never look at the Sun without proper eye
protection. Instead, go to http://goo.gl/XIBh6
for images of the Sun and more information about the telescope.
Wednesday:
Mars is less than a fist above the southeast horizon at 7:30 p.m.
Thursday: At
10:30 p.m., Jupiter is about one 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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