Saturday: You know Metis
and Thebe and Adrastea and Amalthea. Io and Ganymede and Callisto and Europa.
But do you recall? There are 79 Jovian moons in all. 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 79 moons range in
size from Ganymede, the largest in the Solar System with a diameter of 5,262
kilometers, to numerous moons with diameters of only one kilometer. Recently,
Saturn moved into first in the moon race with 82. Uranus is next with 27. Then
comes Neptune with 14, Mars with 2, and Earth with 1. Our moon is the fifth
largest in the Solar System, with a diameter of 3,475 kilometers. (One
kilometer is 0.62 miles.) Even dwarf planets have moons. Pluto has 5, Eris has
1, Haumea has 2, and Makemake has 1. 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 in diameter
than Pluto.) Haumea, the newest dwarf planet with a moon, was discovered in
2004 and officially named a dwarf planet on September 17, 2008. Go to https://solarsystem.nasa.gov/moons/ for more information about
Solar System moons.
Sunday: So you think your
mother has problems on Mother’s Day because she has you as a child? Her mother
issues can’t be as bad as Cassiopeia’s issues. First, she was chained to a
chair for boasting about her beauty. Second, she has to revolve around the
North Star night after night. Third, her daughter Andromeda was nearly killed
by a sea monster. Look for poor Cassiopeia about one and a half fists held
upright and at arm’s length above the northern horizon at 10:00 p.m. Cassiopeia
looks like a stretched out “W”.
Monday: Monday: Give me an
“M”. Give me a “3”. What does that spell? “M3.” “Big deal,” you say. It was a
big deal to French comet hunter Charles Messier (pronounced Messy A). M3 was
the 3rd comet look-alike that Messier catalogued in the late 1700s. M3 is
a globular cluster, a cluster of over 100,000 stars that is 32,000 light years
away. It is too dim to be seen with the naked eye but is fairly easy to find
with binoculars. First find Arcturus six fists above the southeastern horizon
at 11:00 p.m. Move your binoculars up one binocular field of view so two stars
of nearly identical brightness are in your field of view. When the top star is
in the lower left part of your field of view, there should be a fuzzy patch
near the center of your field of view. This is M3.
Tuesday: The Moon, Jupiter,
and Saturn are very close together in the south-southeastern sky from the time
they rise at about 1:30 a.m. until Sunrise. But why limit yourself to nighttime
observing. Using binoculars, and with the Moon as your guide, you should be
able to see Jupiter and Saturn. First, find the Moon with binoculars and
move the Moon to the bottom of your field of view. Jupiter will be easily
visible to the upper right of the Moon and Saturn will likely
Wednesday: Venus is one and
a half fists above the west-northwest horizon at 9:30 p.m.
Thursday: Mars’ two small
moons, Phobos and Deimos, are not visible in typical backyard telescopes. But
they are an interesting study. The former view among astronomers was that both
moons are captured asteroids. That makes sense given Mars’ proximity to the
asteroid belt. But recent findings by European astronomers indicate that Phobos
is very porous and made of material similar to the surface of Mars. This
implies that Phobos may consist of chunks of Martian debris that was blasted
off by numerous impacts and gravitationally bound together. Unfortunately, the
Russian Phobos-Grunt probe launched late 2011 to collect material from Phobos
crashed to Earth after malfunctioning. For more information about this recent
model of Phobos’ formation, go to
https://sci.esa.int/web/mars-express/-/31031-phobos. For more information about
Mars, look two fists above due southeast at 5:00 a.m., right next to our Moon.
Friday: Comet SWAN may save
the day! Although Comet ATLAS broke up and will not be the bright fuzzball we
all expected, Comet SWAN will likely be easily visible with binoculars and may
be visible with the naked eye. Look for it at 4:30 a.m. about one fist above
the east-northeastern horizon. First find Hamal, the brightest star in the
area, a little less than one fist above the east-northeastern horizon. With
Hamal in the lower left portion of your binocular field of view, Comet SWAN
will be in the center to upper right portion of the field of view. For more information,
including a finder chart, go to
https://skyandtelescope.org/astronomy-news/comet-swan-expected-to-put-on-a-splendid-show/
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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