Skylights featured on Astronomy Picture of the Day

Scout Report Selection Webivore Selection SpaceCareers Selection

Skylights featured nine times on Earth Science Picture of the Day: 1 2 3 4 5 6 7 8 9 -- Full List Restored!


Photo of the Week. Jupiter, as seen through 26-inch refractor of the US Naval Observatory at 10:48 PM EDT on April 5, 2016, is covered with turbulent ammonia and hydrocarbon clouds. The southern hemisphere's obvious Great Red Spot, an anticyclone twice the size of Earth, has been diminishing over the past century or so. Image by Geoff Chester, with thanks.

Astronomy news for the two weeks starting Friday, May 6, 2016.

The next skylights will appear May 20.

Again the fortnight tracks the lunar phases. We start at new Moon on Friday, May 6, the thin crescent first becoming visible in western twilight the evening of Saturday, May 7. The evening of Sunday the 8th finds the waxing crescent to the right of Betelgeuse in Orion. The phase is terminated at first quarter on Friday the 13th (good luck to all) with the Moon beneath Regulus in Leo. The waxing gibbous Moon then finds itself southwest of Jupiter the night of Saturday the 14th, while the following evening it moves off to the east of the planet heading toward full phase on Saturday the 21st, when it will be to the left of Mars and above Saturn . Our period ends the previous night with the Moon to the northwest of the red planet. During the fortnight the Moon also moves slightly away from the Earth on its elliptical path, crossing apogee (farthest from Earth, 5.5 percent more distant than average) three days before full, which will weaken the high tides at the coasts.

Jupiter, high in the sky to the western side of the celestial meridian by the end of evening twilight, ceases retrograde (westward motion against the background stars) on Monday the 9th. The giant planet sets shortly before dawn. On the other side of the sky Mars rises in the southeast as twilight fades, followed half an hour later by Saturn, the two making a nice show with Antares in Scorpius.

The big event belongs to Mercury , which not only goes through inferior conjunction with the Sun on Monday the 9th, but also transits across the Sun. The transit begins at 6:12 AM CDT, when Mercury hits the eastern solar limb. Mid-transit just south of the solar disk is passed at 9:58 AM CDT and the event is over at 1:42 PM CDT when the Moon leaves the western solar limb. (Add an hour for EDT, subtract an hour for MDT, two hours for PDT). A properly-filtered telescope is needed to see little Mercury, which will appear as a small but very black dot just 10 seconds of arc across. Do NOT attempt viewing without a proper, commercially-made, solar filter. Home- made ones have been known to burst into flame. Projection is safest. Transits of Mercury are centered around November 9 and May 7 separated by intervals of 7 and 14 years, the November events twice as common. The next one will be November 11, 2019. Transits of Venus are much rarer. The last one took place in 2012 and we won't see another until 2117. The transits of Mercury have a long history in the establishment of longitude, as they make a natural clock with which to tell Greenwich time (which compared to local time yields east-west global position).

Though the whole constellation is not visible from mid-northern latitudes, the northern portion of Centaurus, the Centaur, crosses the meridian to the south in late evening. It's followed by the stars of Lupus, the Wolf, then by Scorpius, the Scorpion and by Sagittarius, the Archer, which is yet another Centaur, the mythological figure apparently quite popular among the ancients.
Valid HTML 4.0!