The Sky Tonight
- From AOL News:
Look to Sky for Spectacular Sight Monday
By Joe Rao
(Nov. 29) - Every once in a while, something will appear in the night
sky that will attract the attention of even those who normally don't
bother looking up. It's likely to be that way on Monday evening, Dec. 1.
A slender crescent moon, just 15-percent illuminated, will appear in
very close proximity to the two brightest planets in our sky, Venus
People who are unaware or have no advance notice will almost certainly
wonder, as they cast a casual glance toward the moon on that night,
what those two "large silvery stars" happen to be? Sometimes, such an
occasion brings with it a sudden spike of phone calls to local
planetariums, weather offices and even police precincts. Not a few of
these calls excitedly inquire about "the UFOs" that are hovering in
the vicinity of our natural satellite.
A Rare Alignment
On Monday night, the three brightest objects in the night sky --
Jupiter, Venus and the moon -- will line up close together in a
spectacular sight, closer than they will appear until 2052. One expert
said the alignment, captured here in 2004, will "be a head-turner."
Click through the rest of the gallery for some amazing space images.
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Very Bright Objects
Venus has adorned the southwestern twilight sky since late August. No
other star or planet can come close to matching Venus in brilliance.
During World War II, aircraft spotters sometimes mistook Venus for an
enemy airplane. There were even cases in which Venus drew antiaircraft
This winter, Venus is the unrivaled evening star that will soar from
excellent to magnificent prominence in the southwest at nightfall. The
interval by which it follows the Sun will increase from nearly three
hours on Dec. 1 to almost four hours by Jan. 1. It's probably the
first "star" you'll see coming out after sunset. In fact, if the air
is very clear and the sky a good, deep blue, try looking for Venus
shortly before sunset.
Jupiter starts December just above Venus and is moving in the opposite
direction, dropping progressively lower each evening. By month's end
Jupiter meets up with another planet Mercury but by then Jupiter
is also descending deep into the glow of sunset. In January, Jupiter
will be too close to the Sun to see; it's in conjunction with the Sun
on Jan. 24.
A very close conjunction of the crescent moon and a bright star or
planet can be an awe-inspiring naked-eye spectacle. The English poet,
critic and philosopher, Samuel Taylor Coleridge (1772-1834) used just
such a celestial sight as an ominous portent in his epic, "The Rime of
the Ancient Mariner." In addition, there are juxtaposed crescent moon
and star symbols that have appeared on the flags of many nations,
including Turkey, Pakistan, Malaysia, Algeria, Mauritania, and Tunisia.
Also on Monday evening, you may be able to see the full globe of the
moon, its darkened portion glowing with a bluish-gray hue interposed
between the sunlit crescent and not much darker sky. This vision is
sometimes called "the old moon in the young moon's arms." Leonardo da
Vinci (1452-1519) was the first to recognize it as what we now call
As seen from the moon, the Earth would loom in the sky some 3.7 times
larger than the moon does for us. In addition, the land masses, the
oceans and clouds make the Earth a far better reflector of sunlight as
compared to the moon. In fact, the Earth's reflectivity varies as
clouds, which appear far more brilliant than the land and seas, cover
greater or lesser parts of the visible hemisphere. The result is that
the Earth shines between 45 and 100 times more brightly than the moon.
The Earth also goes through phases, just as the moon does for us,
although they are opposite from what we see from Earth. The term for
this is called "complementary phases." On Nov. 27, for example, there
was a new moon for us, but as seen from the surface of the moon that
day, there appeared in the lunar sky a brilliant full Earth. A few
nights later, as the sliver of a crescent moon begins to appear in our
western twilight sky, its entire globe may be glimpsed.
Sunlight is responsible for the slender crescent, yet the remainder of
the moon appears to shine with a dim blush-gray tone. That part is not
receiving sunlight, but shines by virtue of reflected earthlight: the
nearly full Earth illuminating the otherwise dark lunar landscape. So
earthshine is really sunlight which is reflected off Earth to the moon
and then reflected back to Earth.
Keeping It All in Perspective
Keep in mind that this head-turning display of three celestial objects
crowded together will be merely an illusion of perspective: the moon
will be only about 251,400 miles from Earth, while Venus is nearly 371
times farther away, at 93.2 million miles. Meanwhile, Jupiter is
almost 2,150 times farther away than our natural satellite at 540.3
Those using binoculars or a small telescope will certainly enjoy the
almost three-dimensional aspect of the moon, but Venus will be rather
disappointing appearing only as a brilliant blob of light, for right
now, it's a small, featureless gibbous disk. That will change in the
coming weeks, however, as Venus approaches Earth and the angle it
makes between us and the Sun allows it to evolve into a "half-moon"
phase in mid January, and a lovely crescent phase of its own during
the latter part of February and March.
Jupiter on the other hand is a far more pleasing sight with its
relatively large disk, cloud bands and its retinue of bright Galilean
satellites. All four will be in view on Monday evening, with Callisto
sitting alone on one side of Jupiter, Ganymede, Io and Europa will be
on the other side. Io and Europa will in fact, appear very close to
each other, separated by only about one-sixth the apparent width of
Venus 'Eclipse' for Europe
As beautiful as the view of Venus, Jupiter and the moon will be from
North America, an even more spectacular sight awaits those living in
parts of Western Europe where the moon will pass in front of Venus.
Astronomers refer to this phenomenon as an "occultation," taken from
the Latin word occultare, which means "to conceal." This eye-catching
sight will be visible in complete darkness across much of Eastern
Europe. Farther west, Venus will disappear behind the dark part of the
moon either during evening twilight or just before the Sun sets. When
Venus emerges, it will look like a brightening jewel on the slender
lunar crescent. For virtually all of Europe, the Sun will have set by
then, the exception being southern Portugal (including Lisbon).
Such favorable circumstances are quite rare for any given location.
For example, the last time London was treated to such a favorably
placed Venus occultation such was back on October 7, 1961. And after
2008, there will not be another similarly favorable Venus occultation
for the United Kingdom until January 10, 2032. So be sure to make the
most of this upcoming opportunity. More detailed information,
including maps of the occultation zone, as well as times for dozens of
European cities, are here