Skylights featured on Astronomy Picture of the Day

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


Photo of the Week. Yet another summer rose framed by the blue sky.

Astronomy news for the week starting Friday, April 23, 2010.

The Moon brightens the evening sky in its waxing gibbous phase as it heads toward full, that phase reached the morning of Wednesday, April 28, just about the time of Moonset in North America, when it will set almost exactly at sunrise. That night it will rise a bit after the Sun goes down. Following full, we get a couple days of the waning gibbous, the perpetual tale to be picked up again next week. On Saturday the 24th, the Moon passes perigee, where it is closet to the Earth.

The night of Sunday the 25th, the Moon passes eight degrees south of Saturn, which will provide a great way of identifying the ringed planet. The rather large separation between the two is caused by orbital tilts. Saturn is close to its maximum angular distance almost three degrees north of the ecliptic (the apparent path of the Sun), while the Moon will be near its maximum five-degree angle south of it.

Placement of the planets allows us to proceed pretty much from inside out. Mercury, now gone from the visible sky, passes inferior conjunction with the Sun, on the near side, on Wednesday the 28th. Venus, on the other hand, picks up steam. Climbing ever higher into the west- northwestern evening sky, the brilliant planet is now setting after the end of twilight, around 10 PM Daylight Time. Which brings us to Mars. At twilight's end a bit past the meridian into the southwest, the red planet (really more of an orange flavor) is beautifully placed between Gemini's Castor-Pollux pair and Regulus in Leo and, though fading, is brighter than any of the three stars. Compare its color to orange Pollux, the left-hand star of the pair. It finally sets around 3 AM Daylight Time

Then we go a bit out of order and back to Saturn, which is being visited by the Moon. Almost exactly between Regulus and Virgo's Spica and on its retrograde trek against the stars, it passes 2.75 degrees due north of the Autumnal Equinox on Saturday the 24th. Transiting the meridian near 10:30 PM, Saturn does not set until mid-twilight, about the time that Jupiter -- still a tough find -- rises.

The sky made news the evening of Wednesday, April 14, with a splashy fireball meteor. It was most likely a small, uncatalogued visitor from the asteroid belt a meter or two in diameter. Moving at ten or more kilometers per second, the meteoroid carved a hot bright path through the Earth's atmosphere 100 kilometers up, exploded, then sent a shower of stones to the ground as meteorites. Such events are completely unpredictable.

As April turns to May, Ursa Major's Big Dipper circles high overhead in the late evening. For a minimal test of vision, see if you can find little Alcor, which is nearly hidden next to Mizar, the second star in from the end of the handle. To the south and west of the Dipper, find three pretty pairs of stars that the Arab's called the "leaps of the gazelle."
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