Skylights featured on Astronomy Picture of the Day

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


Photo of the Week.. The Sun, as seen with low magnifying power on Thursday, October 30, 2003, displayed not one, but two, gigantic sunspot groups on either side of the solar equator. Note that the edge (the limb) of the Sun is dimmer than the center (a phenomenon called limb darkening), a consequence of the Sun being spherical and gaseous. The result is that we look slightly deeper into the Sun at the center than at the edge, and therefore to hotter and brighter gases.

Astronomy news for the week starting Friday, November 7, 2003.

This week we celebrate our two constant companions, the Moon and the Sun. The Moon begins the week not quite full, passing the phase on Saturday, November 8, when it will plunge through the shadow of the Earth to be eclipsed, the second total eclipse of the year to be seen in North America. This one is beautifully timed for the east, not quite so for the west. The partial phase, wherein the Moon enters the full shadow of the Earth, begins at 5:32 PM Central Time (add one hour for EST, subtract an hour for MST, two hours for PST). For the eastern part of the US and Canada, the eclipse will begin after sundown (and, since the Moon is full, Moonrise). For the west, the Moon will rise already partially eclipsed, actually producing quite the fascinating sight. The Moon fully enters total shadow at 7:06 PM (CST), leaves it at 7:31 PM, and then finishes the partial stage at 9:04. Totality does not last very long, as the Moon is a bit south of the ecliptic, and really just clips full shadow. The shadow is not fully dark, but is lit by sunlight scattered by and refracted through the Earth's atmosphere, its brightness depending on atmospheric opacity, mostly that caused by volcanic eruptions. The result at central eclipse at 7:18 (CST) is that the south part of the Moon will be notably brighter than the northern part, which will be closer to the central part of the shadow.

The Sun (which with the Earth is the cause of the eclipse in the first place) got additionally into the act through the great coronal mass ejection of last week, the event caused by the collapse of magnetic fields associated with the huge sunspot groups that paraded across the apparent solar disk. (The "corona" that surrounds the Sun and is seen during a solar eclipse is heated to two million degrees and supported by solar magnetism.) Though the Sun is now on the downside of its 11-year cycle, it is still capable of producing powerful magnetic activity. The ejections from the corona of the Sun hit the Earth and disturbed the magnetic field, producing northern and southern lights, and disturbing communications. More events are always possible (but impossible to predict until we see the Sun actually eject the matter), so keep your eyes on the nightly skies (though not on the Sun itself, which is dangerous to look at).

Beyond the Moon and Sun, Venus, slowly climbing the southwestern skies in evening twilight, passes north of Antares in Scorpius the night of Sunday, November 9, the planet still difficult to see. The Moon will then be seen to the northwest of Saturn the night of Wednesday, the 12th, then to the northeast of it on Thursday, the 13th. Mars, of course, still glowers to the south in the evening hours, while bright Jupiter dominates the early morning skies to the east, below the brave figure of Leo.

This is Cassiopeia season, the famed "W" appearing upside down as it crosses the meridian to the north of overhead around 10 PM, the constellation that represents the ancient Queen set within a remarkable part of the Milky Way, which can be admired once the Moon moves out of the way.
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