This is the Skywatch Line for Monday and Tuesday, March 13th and 14th.
Now that Daylight Savings Time is in effect, the Sun sets at 7 PM; night falls at 8:34. Dawn breaks at 5:34 AM and ends with sunrise at 7:08.
Two bright and one dim planets appear in the darkening western sky. Venus, in Pisces, is the brightest and lowest at 13 degrees altitude. It glares at minus 4.3 magnitude, is large in our instruments at 56 arc-seconds, but shows only a very thin crescent at 5.6 percent. It sets at 8:44 PM. Mars, in Aries, is second brightest at first magnitude and appears nearly full, but is a tiny 4 arc-seconds in size; it hovers 31 degrees above the western horizon. It sets at 10:21 PM. Uranus, in Pisces, is dimmest at sixth magnitude, appears smaller than Mars in our telescopes and is 21 degrees high; it sets at 9:27 PM.
The just-passed-full Moon rises at 8:13 PM in Virgo and blazes at minus 12th magnitude. Tuesday finds it rising in Virgo at 9:14 PM. The rising Moon will blot out most deep-sky objects, like galaxies and nebulas. However, the Moon will not obscure the giant planet Jupiter, which also rises in Virgo at 9:11 PM. Jupiter, the Moon and Virgo’s bright star Spica will form an attractive triangle Tuesday night.
Jupiter shines at minus 2.4 magnitude and appears a large 43 arc-seconds in size. The giant planet remains up all night. Astronomers can have a double treat from Jupiter. The Great Red Spot, a giant storm, will be visible at 3:18 AM and at 11:09 PM on Tuesday. Jupiter’s moon Europa disappears behind the giant planet at 4:37 AM also on Tuesday.
Twilight affords a challenge object, the asteroid 4Vesta. It’s about one-and-a-half degrees below the star Upsilon Geminorum. It shines at seventh magnitude and is a tiny 0.4 seconds in size, requiring detailed star charts from astronomy media. Observers should try before the Moon gets too high in the sky.
Saturn rises in Sagittarius at 2:40 AM. It shines at 0.5 magnitude and presents a modest 16 arc-seconds in our telescopes. Saturn is best observed before Dawn breaks at 5:34 AM; it should be far enough from the Moon to enjoy views of its rings.
March 17 is the 362nd anniversary of Christian Huygens’ discovery of the Saturnian moon Titan. Christian Huygens was a Seventeenth Century scientific giant. He made discoveries in the fields of: astronomy, game theory and horology (time). He improved spherical telescope lenses; today, astronomers still use Huygens eyepieces. He observed the 1661 transit of Mercury across the Sun, worked on laws of gravity and light, invented the first projector, the first pendulum clock and improved the pocket watch. While Galileo first observed Saturn through a telescope, he was confused by the rings, which he called “ears.” Huygens, observing Saturn with a fifty-power telescope, was the first to call them a ring; later observers discovered gaps in the rings. Huygens even published a book on extra-terrestrial life.
For his many accomplishments, Huygens was honored. The Cassini space probe of Saturn carried the Huygens lander. Asteroid 2801 was named for him, as were a crater on Mars and a mountain on the Moon.