SKYLIGHTS

Skylights featured on Astronomy Picture of the Day

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Skylights featured five times on Earth Science Picture of the Day:
1 , 2 , 3 , 4 , 5

thunderstorm

Photo of the Week.. In the first of a short series, a thunderstorm, illuminated by a setting Sun and seen from an aircraft flying at the same altitude, roils away against the blue of a distant sky.


Astronomy news for the week starting Friday, July 15, 2005.


A month after the passage of the Sun over the Summer Solstice, the Moon passes its full phase the night of Wednesday, July 20th, about halfway between the classical figures of Sagittarius and Capricornus, not quite as far south as last month's full Moon but close, since (because of the lunar orbital tilt) the full Moon will be rather well below the ecliptic. Prior to full, watch as the waxing gibbous, rising ever later, descends ever deeper to the south, passing through Scorpius and near Antares the night of Sunday the 17th.

In North America, the full phase actually takes place about moonset the morning of Thursday the 21st, when it will set at sunrise. The night of the 20th thus finds our neighbor just short of technical full, causing it to rise a bit before sunset. Only nine hours past full, the Moon passes its perigee, where it is closest to the Earth, producing one of the angularly largest full Moons of the year. The effect, while photographable, cannot be seen with the naked eye. That the rising Moon looks very large is strictly an optical illusion, indeed is called "the Moon illusion."

The western evening sky still intrigues. Though Saturn is gone, and will soon (next week) pass conjunction with the Sun, and though Mercury has dropped nearly out of sight, Venus climbs yet higher and is now obvious in the western twilight sky just a bit to the north of due west. As the week proceeds, Venus moves easterly against the stars at the same time the constellations slip to the west, causing Venus and Regulus in Leo to approach each other, the pair coming into nice conjunction on Friday the 22nd. On a larger angular scale, Venus and Jupiter (Jupiter in Virgo to the west of Spica) slowly approach as well, the giant planet nicely visible in the southwest in early evening and not setting until around midnight Daylight Time (making it fully an evening object). Half an hour after Jupiter sets, Mars (in Pisces) rises, the red planet best viewable in the later morning hours.

This is the season to admire great Scorpius (the figure looking for all the world like a giant scorpion), best visible now to the far south around 10 PM Daylight Time, though the bright Moon will for a time make it rather difficult to see in all its detail. Less known in the northern hemisphere is a bright, beautiful constellation to the southwest of Scorpius, Lupus (the Wolf), which connects nicely with Centaurus (the Centaur), which lies even farther to the southwest, and which in turn lies to the north of one of the most famed figures of the sky, Crux, the Southern Cross.
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