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Astronomy Picture of the Day

Red Sunrise

Photo of the Week.. A red sunrise lights the eastern sky.

Astronomy news for the week starting Friday, September 13, 2002.

The week begins with the Moon in its first quarter, the phase reached just about the time of Moonrise in North America. On the average rising near noon, the first quarter is a fine time to watch the Moon progress up the eastern sky during the daytime. With the Sun approaching the autumnal equinox in Virgo, the first quarter will lie just shy of the winter solstice in Sagittarius, making it the most southerly first quarter of the year. As the Moon progresses through its waxing gibbous phase, it rises progressively later until, when full phase is reached on Saturday the 21st, it will rise around sunset. During this waxing stage it will pass beneath Neptune the night of Monday the 16th, and south of Uranus on Wednesday the 18th.

Though the Sun is getting closer to Venus, the planet is still in direct, or easterly, motion against the starry background; the Sun is simply moving faster along the ecliptic and is catching up with it. Venus is also still increasing in brightness, though the increase is not obvious as the planet is now rather low against the western horizon at dusk. Through the telescope Venus is now presenting itself as a large crescent. Little Mercury, on the other hand, enters its backward, or retrograde, motion on Saturday the 14th, the planet all but invisible against twilight glare.

With the inner planets disappearing into western twilight, the giants begin to move into the evening. Saturn now rises in Taurus just before midnight daylight time. Jupiter, brightly visible to the east in morning twilight, will enter the evening sky in late October. Mars has also cleared the Sun. Rising in bright morning twilight, it is now about as elusive as Mercury.

As the Sun approaches the equinox, note that it lies due west shortly before sunset, and due east shortly after sunrise, making driving east and west in morning or evening rather difficult. At this time of year, the Sun is trekking quickly to the south, making the movement of the sunset point along the horizon quite obvious.

As the sky darkens, the great Summer Triangle is now in full bloom, Vega nearly overhead, Deneb to the northeast, Altair to the south. Near and within its confines lie two exquisite constellations, Delphinus, the Dolphin (which looks like a small hand pointing a finger), and Sagitta, the Arrow (which rather looks like what it is supposed to be), the two bracketing the line between Deneb and Altair. For a celestial challenge, try to find the modern constellation of Vulpecula, the Fox, which lies between Sagitta and Albireo, the star that represents the head of Cygnus, the Swan (Deneb making the tail).
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