 Saturn – the ringed planet can be seen high in the SE just after dusk and remains well–placed for viewing till about 2 am. Look for it 56 degrees high in the south by 9 pm EDT at mid–month. Saturn will then be magnitude 0.8 with an apparent diameter of 18 arc–seconds. The rings will be 40 arc-seconds across with a tilt of only 4 degrees to our line–of–sight. The Sun crossed Saturn's ring plane in early March, moving from south to north. Since the south side of the rings is still tilted slightly to our view here on Earth, the rings will become much darker than they have been lately. We will see them only by sunlight scattered through the rings.
Because the rings are so close to edge–on right now, we can see transits of Saturn's many moons and their shadows across the disc of Saturn. The largest moon, Titan, will have its shadow transit on May 15th, beginning at 1:30 am EDT and again on the 31st, beginning at 12:30 am. Titan's shadow will look like a black dot crossing Saturn. Titan itself will pass just to the north of Saturn.
The Cassini spacecraft continues its observation of Saturn and its many moons and rings. For the latest images from Cassini, see:
http://saturn.jpl.nasa.gov/home/index.cfm
For detailed postions of Saturn's Moons try this interactive javascript utility. |
Mercury – visible in the evening sky during early May. Look for it 5 to 10 degrees up in the WNW a half–hour after sunset. It will be 1st magnitude. Mercury is 2 degrees to the left of the Pleiades star cluster at the beginning of May.
Venus – is now the "morning star" until October. Look for it 17 degrees up in the east at sunrise at the beginning of May, increasing to 22 degrees by the end of the month. Venus will be magnitude –4.5 to –4.3 and have a diameter that decreases from 40 to 25 arc–seconds. The phase will range from a large crescent in early May to almost half–lit by month's end. Early in the month, it may be possible to see the crescent with binoculars if they are held steadily enough. Venus can actually be seen in the daytime if you know where to look, just be sure to block the Sun with something (tree, building, etc.) to avoid accidentally aiming your scope or binoculars at the Sun!
Mars – has now entered the morning sky as well, beginning a new apparition that will lead up to its next opposition in January, 2010. Look for it about 10 degrees up in the east a half–hour before sunrise. The "red planet" will be magnitude 1.2 and have a diameter of 4.6 arc–seconds.
Jupiter – is best seen about an hour before dawn. On May 20, Jupiter is just 0.1 degree south of the fifth–magnitude star Mu Capricorni. It passes 0.4 degree south of Neptune on May 25. Ganymede occults Io on May 4 at 5:35 a.m. EDT and Europa on May 11 at 4:19 a.m. EDT.
Uranus – will be tough to spot this month but not impossible. It is in the predawn sky in the east. It will be shining at magnitude 5.9 in Pisces. This puts it below Jupiter but above Venus. Uranus shines with a pale aquamarine color. It is bright enough to be a marginal naked eye target under ideal conditions and an easy binocular target.
Neptune – will be at magnitude 7.9 this month. This makes it an easy binocular target from dark skies. The much brighter Jupiter will be very close all month. On the 25th Jupiter will be less than half a degree to the south. Neptune shines a pale blue in color.
Pluto – is higher in the sky than Venus, Mars and Jupiter but still may not be high enough to see. It will sit north of Sagittarius in the Milky Way "cloud" in the morning sky. A few hours after midnight when it has climbed high in the south will be the best time to look for it. At magnitude 13.9 Pluto is always a very tough target. You need dark still skies, a good chart, at least an 8 telescope and patience to find it.
Eris (pronounced "EE-ris") – formerly known as Xena, 2003 UB313, and "the tenth planet" – is magnitude 19 in central Cetus, high in the south during evening.