Saturday: Do people think you have a magnetic personality? The
star Cor Caroli understands how you feel. Cor Caroli has one of the strongest
magnetic fields among main sequence stars similar to our Sun. This strong
magnetic field is thought to produce large sunspots that cause the brightness
of Cor Caroli to vary. Cor Caroli is nearly straight overhead at 11:30 p.m.
Sunday: Venus is nearly a half a fist held upright and at
arm’s length above the east horizon at 5 a.m.
Monday: You know Metis and Thebe and Adrastea and Amalthea.
Io and Ganymede and Callisto and Europa. But do you recall? There are 67 Jovian
moons in all. (As of July 2013.) Just 60 years ago, Jupiter was thought to have
only 12 moons. But, astronomers are red-nosed with delight that the advent of
supersensitive electronic cameras has caused the number of discovered moons to
rapidly increase. Jupiter’s 67 moons range in size from Ganymede, with a
diameter of 5,262 kilometers, to S/2002 J12 and S/2003 J9, with a diameter of
only one kilometer. Our moon has a diameter of 3,475 kilometers. (One kilometer
is 0.62 miles.) Saturn is second place in the moon race with 62. Uranus is next
with 27. Then comes Neptune with 14, Mars with 2, and Earth with 1. Even dwarf
planets have moons. Pluto has 5, Eris has 1, and Haumea has 2. Eris is an outer
solar system object that was discovered in 2005 and named in September of 2006.
Because astronomers thought it was larger than Pluto, people called it the
tenth planet for a while. (More recent measurements show Eris to be a little
smaller than Pluto.) Haumea, the newest dwarf planet with a moon, was
discovered in 2004 and officially named a dwarf planet on September 17, 2008.
Jupiter, the “mooning” champ, is four fists above the west horizon at 9 p.m. Go
to http://goo.gl/Xkoeq for more information about Solar System moons.
Tuesday: Tonight’s Moon is new. Don’t bother looking for it.
The new moon is the phase where the Moon is directly between the Earth and the
Sun. Hence the side of the Moon facing Earth is not receiving any sunlight and
cannot be seen. However, if you are visiting Australia or Antarctica today, its
effects can be seen. There will be an annular solar eclipse visible in part of
Antarctica and a partial solar eclipse visible in all of Australia. For more
information about this phenomenon, where the moon will block part of the Sun’s
light, go to http://goo.gl/7Ecls0. If
you are reading this from Australia, throw a shrimp on the Barbie and observe
the Sun only through a proper solar filter.
Wednesday: Avast ye matey. Swab the poop deck. Pirates love
astronomy. In fact, the term “poop” in poop deck comes from the French word for
stern (poupe) which comes for the Latin word Puppis. Puppis is a constellation
that represents the raised stern deck of Argo Navis, the ship used by Jason and
the Argonauts in Greek mythology. Argo Nevis was an ancient constellation that
is now divided between the constellations Puppis, Vela and Carina. The top of
Puppis is about a fist and a half to the left of the bright star Sirius in the
south-southwest sky at 9 p.m. Rho Puppis, one of the brightest stars in the
constellation, is about one and a half fists above the south-southwest horizon
at this time.
Thursday: At 10 p.m., Saturn is one fist above the southeast
horizon and Mars is nearly four fists above the south-southeast horizon.
Friday: Winter must be over because the winter
constellations are becoming less visible. Orion is setting in the west starting
at about 9 p.m. At this time, Orion’s belt is a little more than half a fist
above the west horizon and Betelgeuse is nearly two fists above the west
horizon. By mid-May, Orion will be lost in the glare of the Sun.
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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