To date it has been a superb winter for viewing the queen of the planets, Venus.  February marks the pinnacle of its evening visibility as it stands like a sequined showgirl nearly halfway up in the western sky at sunset. Currently shining at its greatest brilliance for this apparition, this dazzling evening star appears as a distinct crescent shape in small telescopes, which is growing progressively larger in size as it approaches our Earth.

And be sure to get out your calendar and put a big circle around Friday, February 27, 2009, for that evening a lovely crescent Moon will appear to snuggle up close to Venus, particularly for skywatchers across the Western Hemisphere.  It will make for an eye-catching scene as the two brightest sky objects of the night dominate the early evening scene for about three hours after sundown; even those who do not normally look up will likely have their attention drawn to this dynamic duo during their normal commute home from work or school.  What will make this array especially attractive is the fact that it will look almost three-dimensional; the Moon will look almost like an eerily illuminated blue and yellow Christmas ball hovering next to the brilliant-white diamond that is Venus.

Sadly, this will be the last in the current series of evening get-togethers between the Moon and Venus, for during March Venus will slide rapidly down into the sunset glow and by month's end will disappear from our evening sky until the spring of 2010.

But again . . . Friday night, February 27 will be the night when the Americas will be greeted with one of the most beautiful Venus-crescent Moon conjunctions possible. The pairing will persist from before sunset on into the depths of darkness.  The time when Moon and planet will appear closest will be around 8:30 p.m. Eastern time (7:30 p.m. Central, 6:30 p.m. Mountain, and 5:30 p.m. Pacific).  Venus will appear to hover approximately 1.5-degrees above and to the right of the 10-percent illuminated Moon (the Moon itself appears one-half degree in diameter).  For cities situated in the Mountain time zone, the time of closest approach will come during evening twilight, while for those in the Pacific time zone it takes place around, or just prior to sunset.

From other places around the world, the pairing will appear a bit different primarily because the Moon appears to move much more rapidly against the background stars than Venus, and also because of the effect of parallax: different viewing angles from different points on our planet.

From Europe, for instance, Venus will appear to hover majestically about 4-degrees directly above the Moon at sunset.  South Americans will see the Moon with Venus to its right; the pair low in the west-northwest at dusk and appearing to set side-by-side.  From Australia, the Moon will be positioned far to the lower left of Venus on the evening of Feb. 27 and a somewhat similar distance to its upper right the following evening.

Finally, if you're watching with some friends, here's a trivia question you might want to pose to them: Of the two which do they believe is the brighter: Venus now at its peak brilliance or the three-day old Moon?  The almanacs say that the Moon is 8.5 times (2.3 magnitudes) brighter, but because its light is not concentrated into a point like Venus, they may have a difficult time believing this!

Without a question of doubt, the most spectacular celestial sight during these final days of November is reserved for the early evening sky. One of my astronomy mentors, Dr. Ken Franklin (1923-2007), a former Chairman and Chief Astronomer here at the Hayden Planetarium often made reference to our dynamic and ever-changing night sky.  Such an eloquent description certainly fits our current evening sky, as we now have a celestial summit meeting in the making in the western evening twilight.

The highlight will be the gradual approach relative to each other of the two brightest planets—Venus and Jupiter—with the waxing crescent Moon joining them on the first evening of December.  For the remainder of November, skywatchers will observe Jupiter and Venus slowly converge on each other in the southwestern sky, right after sunset.  Venus and Jupiter will appear a similar distance apart on both the evenings of November 30 and December 1.  The moment of closest approach will actually come during the early morning hours of December 1, unfortunately when this dynamic duo is below the horizon for North America.  They'll be separated by just over 2°, which corresponds to roughly one-half the distance that separates Pollux from Castor, the Twin Stars of Gemini (The width of your fist, held at arm’s length roughly corresponds to 10°).

The pinnacle, however, will come on early on Monday evening, December 1.

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 that Monday evening when a slender crescent Moon, just 15% illuminated, will appear in very close proximity to Venus and Jupiter.

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 closely in the vicinity of our natural satellite.

A very close conjunction of the crescent Moon and a bright star or planet can be an awe-inspiring naked-eye spectacle. Those involving Venus, Jupiter and the Moon—the three brightest objects in the night sky—always attract the greatest attention of all. Ken would have called it, A beautiful celestial tableau!

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.

Earthshine

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 Earthshine.

As seen from the Moon, the Earth would loom in the sky nearly 3.7 times larger than the Moon does for us.  In addition, the land masses, the oceans, and clouds make the Earth a much 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 Thanksgiving Day, for example, when the Moon is New for us, as seen from the surface of the Moon, the Earth appears Full. 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 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.

Venus and Jupiter

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.

No question about it.  It will hardly be an evening spending time watching TV!  If the weather is clear between about 5 and 7 p.m. next Monday, be sure to get out and take a look.