Saturday: You know Metis and Thebe and Adrastea and Amalthea. Io and Ganymede and Callisto and Europa. But do you recall? There are 63 Jovian moons in all. Less than 50 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 63 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 61 (up from 60 last year at this time). Uranus is next with 27. Then comes Neptune with 13, Mars with 2, and Earth with 1. Even dwarf planets have moons. Pluto has 3, 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 it is larger than Pluto, people called it the tenth planet for a while. Haumea, the newest dwarf planet, was discovered in 2004 and officially named a dwarf planet on September 17, 2008. Jupiter, the moon leader, is just above the east horizon at 5 a.m. Go to http://www.skyandtelescope.com/observing/objects/planets/A_Guide_to_Planetary_Satellites.html for more information about moons.
Sunday: Saturn is four and a half fists held upright and at arm’s length above the south horizon at 10 p.m., about a fist above the Moon.
Monday: The Seven Sisters will be taking lessons from a love goddess for the next few nights. Venus, named for the Roman goddess of love, is near the Pleiades, an open star cluster also called the Seven Sisters for the rest of the week. They are a fist above the west-northwest horizon at 9 p.m.
Tuesday: Do you like pop music? You don’t? So, so what. In the first draft of a song on her latest album “Funhouse”, the singer P!nk wrote “Waiter just took my full moon, and gave it to Jessica Simps”. Coincidence? I think not. Some Native American tribes called the April full moon the full pink moon because its arrival coincided with the blooming of wild ground phlox, a pink wild flower. Spica, the brightest star in the constellation Virgo, must like P!nk because it is about a fist above the moon at 10 p.m.
Wednesday: Mars is five fists above the southwest horizon at 10 p.m.
Thursday: Antares is about a fist to the lower left of the Moon just before midnight tonight
Friday: Hydra the sea serpent rears its ugly head in the southwest sky at 10 p.m. First find Procyon. This bright star is two and a half fists above the west-southwest horizon. Next, find Saturn and Regulus right next to each other, five fists above the southwest horizon. Now, draw an imaginary line between Procyon and Regulus. Just below the midway point of that line, you should see a clump of stars that make the shape of a crooked house. This is the head of Hydra.
The positional information in this column about stars and planets is typically accurate for the entire week.
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