Skylights featured on Astronomy Picture of the Day

Scout Report Selection Webivore Selection SpaceCareers Selection

Skylights featured three times on Earth Science Picture of the Day: 1 , 2 , 3 , 4 .

Red Rainbow

Photo of the Week.. The reddened setting Sun gives us an unusual red rainbow, the other colors removed by the thickened Earth's atmosphere.

Astronomy news for the week starting Friday, December 10, 2004.

We pass through new Moon this week, on Saturday December 11th, when it will be completely invisible. Only 20 hours after the new phase, the Moon goes through perigee, the combination bringing especially high tides to the coasts. By the evening of Sunday the 12th you might get a glimpse of an extremely thin waxing crescent during fading twilight. By the next and successive nights, the crescent will be obvious, the dark side glowing with earthlight. On Wednesday the 15th, the Moon will pass south of Neptune in Capricornus, the next day south of Uranus in Aquarius.

That planetary progression is merely the (excuse the expression) "tip of the iceberg." We have an unusual situation here. Mercury passes inferior conjunction with the Sun on Friday the 10th, making it the first planet in the morning sky to the west of the Sun. Pluto comes into conjunction with the Sun on Monday the 13th, and until then it is the last planet in the evening sky to the east of the Sun. Thus for that short interval, the planets are all arrayed outward from the Sun in actual order: Mercury, Venus (ok, we drop Earth), Mars, Jupiter, Saturn, Uranus, Neptune, and ... PLUTO! It means nothing whatever physically. It's just a very rare event, and kind of curious. There is no effect on anybody, or any other planet, whatsoever. Mercury is quite invisible, while Venus, Mars, and Jupiter grace the morning sky in a nice row. Saturn (in Gemini) now rises just an hour after the end of twilight to give us an evening planet, and while Uranus and Neptune are not readily visible, they sure are there over in the far west at sundown; as is ultradim Pluto, which is so close (in angle) to the Sun that it is not visible through any telescope at all.

Of more interest perhaps is one of the best meteor showers of the year, the Geminids. Appearing to radiate from the constellation Gemini, they peak the night of Monday December 13-Tuesday December 14, when an observer under a dark sky might see as many as 100 meteors per minute. The Moon, near new, fully cooperates. The Geminids are debris flaked from what was once thought to be an asteroid, 3200 Phaeton, which is apparently really a dead comet, one with its volatiles burned off by the Sun.

Moving off to the southwest in mid-evenings is Fomalhaut of Piscis Austrinus, the Southern Fish. To the south and a bit west walks Grus, the Crane, while to the southeast is a bright second magnitude star that marks the top of another bird, the imaginary Phoenix, which is supposed to have recreated itself from its own ashes. Farther down yet on a nearly straight line from Fomalhaut through Phoenix, and visible only from the far southern US, is Achernar, at the end of the river Eridanus.
Valid HTML 4.0!