One of the last few Titan shadow transits of the year takes place overnight tonight, with several of Saturn’s other moons visible as well.
Overnight on August 18/19, Titan’s shadow transits Saturn. Also visible are some of the planet’s moons — note that Enceladus and Mimas may be too faint for most telescopes to pick up. Credit: Stellarium/Oleg Pluton
- A Titan shadow transit across Saturn is predicted to occur overnight, starting at 1:26 a.m. EDT on the 19th (for Eastern U.S. observers).
- The shadow’s transit path will be from Saturn’s northeastern to northwestern limb, taking approximately 2.5 hours to traverse half the planetary disk.
- Other Saturnian moons, including Dione, Tethys, and Rhea, will also be visible, with Tethys experiencing an occultation shortly after 3 a.m. EDT.
- This event marks the last Titan shadow transit where the moon itself is too distant to transit simultaneously; future transits will include both moon and shadow.
The second Titan shadow transit of the month occurs overnight tonight, so set your sights on Saturn late this evening. The ringed planet rises in the east around 9:30 P.M. local daylight time, gaining altitude hour by hour. Shining at magnitude 0.7, Saturn is easy to find as the brightest point of light in southwestern Pisces. Observers in the eastern half of the U.S. will have more time before the transit begins to center the ringed world in a telescope and enjoy the lovely view of the 43”-wide ring system surrounding the 19”-wide disk of the planet.
The shadow transit begins at 1:26 a.m. EDT, early on the 19th for half of the U.S. (still the 18th for those in the Mountain and Pacific time zones). The shadow appears at Saturn’s northeastern limb, moving from east to west. Note that mid-8th-magnitude Titan appears quite far from the planet, some 9” northeast of the limb where its shadow appears.
A few other moons should be visible as well: 10th-magnitude Dione, Tethys, and Rhea. Dione is east of Saturn, while Rhea is far west of the planet. Tethys is also west, but moving eastward as it heads for an occultation, first disappearing into the planet’s shadow just southwest of Saturn shortly after 3 A.M. EDT on the 19th.
Meanwhile, it takes about 2.5 hours for Titan’s shadow to travel halfway across the disk. The shadow then finally reaches the northwestern limb and the transit ends by 5:30 a.m. CDT on the 19th, after sunrise in the Eastern time zone.
This is the last time Titan’s shadow will transit with its moon too far from the planet to do the same. Next month, Titan will begin transiting Saturn as well.
Sunrise: 6:15 A.M.
Sunset: 7:52 P.M.
Moonrise: 12:50 A.M.
Moonset: 5:05 P.M.
Moon Phase: Waning crescent (23%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 12 P.M. local time from the same location.
For a look ahead at more upcoming sky events, check out our full Sky This Week column.
